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-rw-r--r--Documentation/DMA-API.txt49
-rw-r--r--Documentation/DMA-mapping.txt26
-rw-r--r--Documentation/DocBook/Makefile2
-rw-r--r--Documentation/DocBook/kernel-api.tmpl1
-rw-r--r--Documentation/DocBook/libata.tmpl49
-rw-r--r--Documentation/acpi-hotkey.txt2
-rw-r--r--Documentation/feature-removal-schedule.txt27
-rw-r--r--Documentation/filesystems/vfs.txt12
-rw-r--r--Documentation/fujitsu/frv/kernel-ABI.txt192
-rw-r--r--Documentation/i2c/busses/i2c-parport16
-rw-r--r--Documentation/input/joystick-parport.txt11
-rw-r--r--Documentation/isdn/README.gigaset286
-rw-r--r--Documentation/kbuild/modules.txt2
-rw-r--r--Documentation/kernel-parameters.txt34
-rw-r--r--Documentation/laptop-mode.txt10
-rw-r--r--Documentation/leds-class.txt71
-rw-r--r--Documentation/memory-barriers.txt1941
-rw-r--r--Documentation/mtrr.txt23
-rw-r--r--Documentation/networking/TODO18
-rw-r--r--Documentation/networking/bcm43xx.txt36
-rw-r--r--Documentation/networking/packet_mmap.txt2
-rw-r--r--Documentation/networking/tuntap.txt2
-rw-r--r--Documentation/networking/xfrm_sync.txt166
-rw-r--r--Documentation/pcmcia/driver-changes.txt6
-rw-r--r--Documentation/powerpc/booting-without-of.txt5
-rw-r--r--Documentation/scsi/scsi_eh.txt14
-rw-r--r--Documentation/scsi/scsi_mid_low_api.txt19
-rw-r--r--Documentation/serial/driver22
-rw-r--r--Documentation/sound/alsa/ALSA-Configuration.txt69
-rw-r--r--Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl16
-rw-r--r--Documentation/video4linux/CARDLIST.saa71345
-rw-r--r--Documentation/video4linux/et61x251.txt (renamed from Documentation/usb/et61x251.txt)0
-rw-r--r--Documentation/video4linux/ibmcam.txt (renamed from Documentation/usb/ibmcam.txt)2
-rw-r--r--Documentation/video4linux/ov511.txt (renamed from Documentation/usb/ov511.txt)11
-rw-r--r--Documentation/video4linux/se401.txt (renamed from Documentation/usb/se401.txt)0
-rw-r--r--Documentation/video4linux/sn9c102.txt (renamed from Documentation/usb/sn9c102.txt)16
-rw-r--r--Documentation/video4linux/stv680.txt (renamed from Documentation/usb/stv680.txt)26
-rw-r--r--Documentation/video4linux/w9968cf.txt (renamed from Documentation/usb/w9968cf.txt)36
-rw-r--r--Documentation/video4linux/zc0301.txt (renamed from Documentation/usb/zc0301.txt)0
-rw-r--r--Documentation/vm/hugetlbpage.txt20
-rw-r--r--Documentation/x86_64/boot-options.txt5
41 files changed, 2968 insertions, 282 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 1af0f2d50220..2ffb0d62f0fe 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -33,7 +33,9 @@ pci_alloc_consistent(struct pci_dev *dev, size_t size,
33 33
34Consistent memory is memory for which a write by either the device or 34Consistent memory is memory for which a write by either the device or
35the processor can immediately be read by the processor or device 35the processor can immediately be read by the processor or device
36without having to worry about caching effects. 36without having to worry about caching effects. (You may however need
37to make sure to flush the processor's write buffers before telling
38devices to read that memory.)
37 39
38This routine allocates a region of <size> bytes of consistent memory. 40This routine allocates a region of <size> bytes of consistent memory.
39it also returns a <dma_handle> which may be cast to an unsigned 41it also returns a <dma_handle> which may be cast to an unsigned
@@ -304,12 +306,12 @@ dma address with dma_mapping_error(). A non zero return value means the mapping
304could not be created and the driver should take appropriate action (eg 306could not be created and the driver should take appropriate action (eg
305reduce current DMA mapping usage or delay and try again later). 307reduce current DMA mapping usage or delay and try again later).
306 308
307int 309 int
308dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, 310 dma_map_sg(struct device *dev, struct scatterlist *sg,
309 enum dma_data_direction direction) 311 int nents, enum dma_data_direction direction)
310int 312 int
311pci_map_sg(struct pci_dev *hwdev, struct scatterlist *sg, 313 pci_map_sg(struct pci_dev *hwdev, struct scatterlist *sg,
312 int nents, int direction) 314 int nents, int direction)
313 315
314Maps a scatter gather list from the block layer. 316Maps a scatter gather list from the block layer.
315 317
@@ -327,12 +329,33 @@ critical that the driver do something, in the case of a block driver
327aborting the request or even oopsing is better than doing nothing and 329aborting the request or even oopsing is better than doing nothing and
328corrupting the filesystem. 330corrupting the filesystem.
329 331
330void 332With scatterlists, you use the resulting mapping like this:
331dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nhwentries, 333
332 enum dma_data_direction direction) 334 int i, count = dma_map_sg(dev, sglist, nents, direction);
333void 335 struct scatterlist *sg;
334pci_unmap_sg(struct pci_dev *hwdev, struct scatterlist *sg, 336
335 int nents, int direction) 337 for (i = 0, sg = sglist; i < count; i++, sg++) {
338 hw_address[i] = sg_dma_address(sg);
339 hw_len[i] = sg_dma_len(sg);
340 }
341
342where nents is the number of entries in the sglist.
343
344The implementation is free to merge several consecutive sglist entries
345into one (e.g. with an IOMMU, or if several pages just happen to be
346physically contiguous) and returns the actual number of sg entries it
347mapped them to. On failure 0, is returned.
348
349Then you should loop count times (note: this can be less than nents times)
350and use sg_dma_address() and sg_dma_len() macros where you previously
351accessed sg->address and sg->length as shown above.
352
353 void
354 dma_unmap_sg(struct device *dev, struct scatterlist *sg,
355 int nhwentries, enum dma_data_direction direction)
356 void
357 pci_unmap_sg(struct pci_dev *hwdev, struct scatterlist *sg,
358 int nents, int direction)
336 359
337unmap the previously mapped scatter/gather list. All the parameters 360unmap the previously mapped scatter/gather list. All the parameters
338must be the same as those and passed in to the scatter/gather mapping 361must be the same as those and passed in to the scatter/gather mapping
diff --git a/Documentation/DMA-mapping.txt b/Documentation/DMA-mapping.txt
index ee4bb73683cd..7c717699032c 100644
--- a/Documentation/DMA-mapping.txt
+++ b/Documentation/DMA-mapping.txt
@@ -58,11 +58,15 @@ translating each of those pages back to a kernel address using
58something like __va(). [ EDIT: Update this when we integrate 58something like __va(). [ EDIT: Update this when we integrate
59Gerd Knorr's generic code which does this. ] 59Gerd Knorr's generic code which does this. ]
60 60
61This rule also means that you may not use kernel image addresses 61This rule also means that you may use neither kernel image addresses
62(ie. items in the kernel's data/text/bss segment, or your driver's) 62(items in data/text/bss segments), nor module image addresses, nor
63nor may you use kernel stack addresses for DMA. Both of these items 63stack addresses for DMA. These could all be mapped somewhere entirely
64might be mapped somewhere entirely different than the rest of physical 64different than the rest of physical memory. Even if those classes of
65memory. 65memory could physically work with DMA, you'd need to ensure the I/O
66buffers were cacheline-aligned. Without that, you'd see cacheline
67sharing problems (data corruption) on CPUs with DMA-incoherent caches.
68(The CPU could write to one word, DMA would write to a different one
69in the same cache line, and one of them could be overwritten.)
66 70
67Also, this means that you cannot take the return of a kmap() 71Also, this means that you cannot take the return of a kmap()
68call and DMA to/from that. This is similar to vmalloc(). 72call and DMA to/from that. This is similar to vmalloc().
@@ -194,7 +198,7 @@ document for how to handle this case.
194Finally, if your device can only drive the low 24-bits of 198Finally, if your device can only drive the low 24-bits of
195address during PCI bus mastering you might do something like: 199address during PCI bus mastering you might do something like:
196 200
197 if (pci_set_dma_mask(pdev, 0x00ffffff)) { 201 if (pci_set_dma_mask(pdev, DMA_24BIT_MASK)) {
198 printk(KERN_WARNING 202 printk(KERN_WARNING
199 "mydev: 24-bit DMA addressing not available.\n"); 203 "mydev: 24-bit DMA addressing not available.\n");
200 goto ignore_this_device; 204 goto ignore_this_device;
@@ -212,7 +216,7 @@ functions (for example a sound card provides playback and record
212functions) and the various different functions have _different_ 216functions) and the various different functions have _different_
213DMA addressing limitations, you may wish to probe each mask and 217DMA addressing limitations, you may wish to probe each mask and
214only provide the functionality which the machine can handle. It 218only provide the functionality which the machine can handle. It
215is important that the last call to pci_set_dma_mask() be for the 219is important that the last call to pci_set_dma_mask() be for the
216most specific mask. 220most specific mask.
217 221
218Here is pseudo-code showing how this might be done: 222Here is pseudo-code showing how this might be done:
@@ -284,6 +288,11 @@ There are two types of DMA mappings:
284 288
285 in order to get correct behavior on all platforms. 289 in order to get correct behavior on all platforms.
286 290
291 Also, on some platforms your driver may need to flush CPU write
292 buffers in much the same way as it needs to flush write buffers
293 found in PCI bridges (such as by reading a register's value
294 after writing it).
295
287- Streaming DMA mappings which are usually mapped for one DMA transfer, 296- Streaming DMA mappings which are usually mapped for one DMA transfer,
288 unmapped right after it (unless you use pci_dma_sync_* below) and for which 297 unmapped right after it (unless you use pci_dma_sync_* below) and for which
289 hardware can optimize for sequential accesses. 298 hardware can optimize for sequential accesses.
@@ -303,6 +312,9 @@ There are two types of DMA mappings:
303 312
304Neither type of DMA mapping has alignment restrictions that come 313Neither type of DMA mapping has alignment restrictions that come
305from PCI, although some devices may have such restrictions. 314from PCI, although some devices may have such restrictions.
315Also, systems with caches that aren't DMA-coherent will work better
316when the underlying buffers don't share cache lines with other data.
317
306 318
307 Using Consistent DMA mappings. 319 Using Consistent DMA mappings.
308 320
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index 7d87dd73cbe4..5a2882d275ba 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -2,7 +2,7 @@
2# This makefile is used to generate the kernel documentation, 2# This makefile is used to generate the kernel documentation,
3# primarily based on in-line comments in various source files. 3# primarily based on in-line comments in various source files.
4# See Documentation/kernel-doc-nano-HOWTO.txt for instruction in how 4# See Documentation/kernel-doc-nano-HOWTO.txt for instruction in how
5# to ducument the SRC - and how to read it. 5# to document the SRC - and how to read it.
6# To add a new book the only step required is to add the book to the 6# To add a new book the only step required is to add the book to the
7# list of DOCBOOKS. 7# list of DOCBOOKS.
8 8
diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl
index 8c9c6704e85b..ca02e04a906c 100644
--- a/Documentation/DocBook/kernel-api.tmpl
+++ b/Documentation/DocBook/kernel-api.tmpl
@@ -322,7 +322,6 @@ X!Earch/i386/kernel/mca.c
322 <chapter id="sysfs"> 322 <chapter id="sysfs">
323 <title>The Filesystem for Exporting Kernel Objects</title> 323 <title>The Filesystem for Exporting Kernel Objects</title>
324!Efs/sysfs/file.c 324!Efs/sysfs/file.c
325!Efs/sysfs/dir.c
326!Efs/sysfs/symlink.c 325!Efs/sysfs/symlink.c
327!Efs/sysfs/bin.c 326!Efs/sysfs/bin.c
328 </chapter> 327 </chapter>
diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl
index d260d92089ad..f869b03929db 100644
--- a/Documentation/DocBook/libata.tmpl
+++ b/Documentation/DocBook/libata.tmpl
@@ -120,14 +120,27 @@ void (*dev_config) (struct ata_port *, struct ata_device *);
120 <programlisting> 120 <programlisting>
121void (*set_piomode) (struct ata_port *, struct ata_device *); 121void (*set_piomode) (struct ata_port *, struct ata_device *);
122void (*set_dmamode) (struct ata_port *, struct ata_device *); 122void (*set_dmamode) (struct ata_port *, struct ata_device *);
123void (*post_set_mode) (struct ata_port *ap); 123void (*post_set_mode) (struct ata_port *);
124unsigned int (*mode_filter) (struct ata_port *, struct ata_device *, unsigned int);
124 </programlisting> 125 </programlisting>
125 126
126 <para> 127 <para>
127 Hooks called prior to the issue of SET FEATURES - XFER MODE 128 Hooks called prior to the issue of SET FEATURES - XFER MODE
128 command. dev->pio_mode is guaranteed to be valid when 129 command. The optional ->mode_filter() hook is called when libata
129 ->set_piomode() is called, and dev->dma_mode is guaranteed to be 130 has built a mask of the possible modes. This is passed to the
130 valid when ->set_dmamode() is called. ->post_set_mode() is 131 ->mode_filter() function which should return a mask of valid modes
132 after filtering those unsuitable due to hardware limits. It is not
133 valid to use this interface to add modes.
134 </para>
135 <para>
136 dev->pio_mode and dev->dma_mode are guaranteed to be valid when
137 ->set_piomode() and when ->set_dmamode() is called. The timings for
138 any other drive sharing the cable will also be valid at this point.
139 That is the library records the decisions for the modes of each
140 drive on a channel before it attempts to set any of them.
141 </para>
142 <para>
143 ->post_set_mode() is
131 called unconditionally, after the SET FEATURES - XFER MODE 144 called unconditionally, after the SET FEATURES - XFER MODE
132 command completes successfully. 145 command completes successfully.
133 </para> 146 </para>
@@ -230,6 +243,32 @@ void (*dev_select)(struct ata_port *ap, unsigned int device);
230 243
231 </sect2> 244 </sect2>
232 245
246 <sect2><title>Private tuning method</title>
247 <programlisting>
248void (*set_mode) (struct ata_port *ap);
249 </programlisting>
250
251 <para>
252 By default libata performs drive and controller tuning in
253 accordance with the ATA timing rules and also applies blacklists
254 and cable limits. Some controllers need special handling and have
255 custom tuning rules, typically raid controllers that use ATA
256 commands but do not actually do drive timing.
257 </para>
258
259 <warning>
260 <para>
261 This hook should not be used to replace the standard controller
262 tuning logic when a controller has quirks. Replacing the default
263 tuning logic in that case would bypass handling for drive and
264 bridge quirks that may be important to data reliability. If a
265 controller needs to filter the mode selection it should use the
266 mode_filter hook instead.
267 </para>
268 </warning>
269
270 </sect2>
271
233 <sect2><title>Reset ATA bus</title> 272 <sect2><title>Reset ATA bus</title>
234 <programlisting> 273 <programlisting>
235void (*phy_reset) (struct ata_port *ap); 274void (*phy_reset) (struct ata_port *ap);
@@ -666,7 +705,7 @@ and other resources, etc.
666 705
667 <sect1><title>ata_scsi_error()</title> 706 <sect1><title>ata_scsi_error()</title>
668 <para> 707 <para>
669 ata_scsi_error() is the current hostt->eh_strategy_handler() 708 ata_scsi_error() is the current transportt->eh_strategy_handler()
670 for libata. As discussed above, this will be entered in two 709 for libata. As discussed above, this will be entered in two
671 cases - timeout and ATAPI error completion. This function 710 cases - timeout and ATAPI error completion. This function
672 calls low level libata driver's eng_timeout() callback, the 711 calls low level libata driver's eng_timeout() callback, the
diff --git a/Documentation/acpi-hotkey.txt b/Documentation/acpi-hotkey.txt
index 744f1aec6553..38040fa37649 100644
--- a/Documentation/acpi-hotkey.txt
+++ b/Documentation/acpi-hotkey.txt
@@ -30,7 +30,7 @@ specific hotkey(event))
30echo "event_num:event_type:event_argument" > 30echo "event_num:event_type:event_argument" >
31 /proc/acpi/hotkey/action. 31 /proc/acpi/hotkey/action.
32The result of the execution of this aml method is 32The result of the execution of this aml method is
33attached to /proc/acpi/hotkey/poll_method, which is dnyamically 33attached to /proc/acpi/hotkey/poll_method, which is dynamically
34created. Please use command "cat /proc/acpi/hotkey/polling_method" 34created. Please use command "cat /proc/acpi/hotkey/polling_method"
35to retrieve it. 35to retrieve it.
36 36
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 495858b236b6..293fed113dff 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -71,14 +71,6 @@ Who: Mauro Carvalho Chehab <mchehab@brturbo.com.br>
71 71
72--------------------------- 72---------------------------
73 73
74What: remove EXPORT_SYMBOL(panic_timeout)
75When: April 2006
76Files: kernel/panic.c
77Why: No modular usage in the kernel.
78Who: Adrian Bunk <bunk@stusta.de>
79
80---------------------------
81
82What: remove EXPORT_SYMBOL(insert_resource) 74What: remove EXPORT_SYMBOL(insert_resource)
83When: April 2006 75When: April 2006
84Files: kernel/resource.c 76Files: kernel/resource.c
@@ -127,13 +119,6 @@ Who: Christoph Hellwig <hch@lst.de>
127 119
128--------------------------- 120---------------------------
129 121
130What: EXPORT_SYMBOL(lookup_hash)
131When: January 2006
132Why: Too low-level interface. Use lookup_one_len or lookup_create instead.
133Who: Christoph Hellwig <hch@lst.de>
134
135---------------------------
136
137What: CONFIG_FORCED_INLINING 122What: CONFIG_FORCED_INLINING
138When: June 2006 123When: June 2006
139Why: Config option is there to see if gcc is good enough. (in january 124Why: Config option is there to see if gcc is good enough. (in january
@@ -241,3 +226,15 @@ Why: The USB subsystem has changed a lot over time, and it has been
241Who: Greg Kroah-Hartman <gregkh@suse.de> 226Who: Greg Kroah-Hartman <gregkh@suse.de>
242 227
243--------------------------- 228---------------------------
229
230What: find_trylock_page
231When: January 2007
232Why: The interface no longer has any callers left in the kernel. It
233 is an odd interface (compared with other find_*_page functions), in
234 that it does not take a refcount to the page, only the page lock.
235 It should be replaced with find_get_page or find_lock_page if possible.
236 This feature removal can be reevaluated if users of the interface
237 cannot cleanly use something else.
238Who: Nick Piggin <npiggin@suse.de>
239
240---------------------------
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index adaa899e5c90..3a2e5520c1e3 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -694,7 +694,7 @@ struct file_operations
694---------------------- 694----------------------
695 695
696This describes how the VFS can manipulate an open file. As of kernel 696This describes how the VFS can manipulate an open file. As of kernel
6972.6.13, the following members are defined: 6972.6.17, the following members are defined:
698 698
699struct file_operations { 699struct file_operations {
700 loff_t (*llseek) (struct file *, loff_t, int); 700 loff_t (*llseek) (struct file *, loff_t, int);
@@ -723,6 +723,10 @@ struct file_operations {
723 int (*check_flags)(int); 723 int (*check_flags)(int);
724 int (*dir_notify)(struct file *filp, unsigned long arg); 724 int (*dir_notify)(struct file *filp, unsigned long arg);
725 int (*flock) (struct file *, int, struct file_lock *); 725 int (*flock) (struct file *, int, struct file_lock *);
726 ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, size_t, unsigned
727int);
728 ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned
729int);
726}; 730};
727 731
728Again, all methods are called without any locks being held, unless 732Again, all methods are called without any locks being held, unless
@@ -790,6 +794,12 @@ otherwise noted.
790 794
791 flock: called by the flock(2) system call 795 flock: called by the flock(2) system call
792 796
797 splice_write: called by the VFS to splice data from a pipe to a file. This
798 method is used by the splice(2) system call
799
800 splice_read: called by the VFS to splice data from file to a pipe. This
801 method is used by the splice(2) system call
802
793Note that the file operations are implemented by the specific 803Note that the file operations are implemented by the specific
794filesystem in which the inode resides. When opening a device node 804filesystem in which the inode resides. When opening a device node
795(character or block special) most filesystems will call special 805(character or block special) most filesystems will call special
diff --git a/Documentation/fujitsu/frv/kernel-ABI.txt b/Documentation/fujitsu/frv/kernel-ABI.txt
index 0ed9b0a779bc..8b0a5fc8bfd9 100644
--- a/Documentation/fujitsu/frv/kernel-ABI.txt
+++ b/Documentation/fujitsu/frv/kernel-ABI.txt
@@ -1,17 +1,19 @@
1 ================================= 1 =================================
2 INTERNAL KERNEL ABI FOR FR-V ARCH 2 INTERNAL KERNEL ABI FOR FR-V ARCH
3 ================================= 3 =================================
4 4
5The internal FRV kernel ABI is not quite the same as the userspace ABI. A number of the registers 5The internal FRV kernel ABI is not quite the same as the userspace ABI. A
6are used for special purposed, and the ABI is not consistent between modules vs core, and MMU vs 6number of the registers are used for special purposed, and the ABI is not
7no-MMU. 7consistent between modules vs core, and MMU vs no-MMU.
8 8
9This partly stems from the fact that FRV CPUs do not have a separate supervisor stack pointer, and 9This partly stems from the fact that FRV CPUs do not have a separate
10most of them do not have any scratch registers, thus requiring at least one general purpose 10supervisor stack pointer, and most of them do not have any scratch
11register to be clobbered in such an event. Also, within the kernel core, it is possible to simply 11registers, thus requiring at least one general purpose register to be
12jump or call directly between functions using a relative offset. This cannot be extended to modules 12clobbered in such an event. Also, within the kernel core, it is possible to
13for the displacement is likely to be too far. Thus in modules the address of a function to call 13simply jump or call directly between functions using a relative offset.
14must be calculated in a register and then used, requiring two extra instructions. 14This cannot be extended to modules for the displacement is likely to be too
15far. Thus in modules the address of a function to call must be calculated
16in a register and then used, requiring two extra instructions.
15 17
16This document has the following sections: 18This document has the following sections:
17 19
@@ -39,7 +41,8 @@ When a system call is made, the following registers are effective:
39CPU OPERATING MODES 41CPU OPERATING MODES
40=================== 42===================
41 43
42The FR-V CPU has three basic operating modes. In order of increasing capability: 44The FR-V CPU has three basic operating modes. In order of increasing
45capability:
43 46
44 (1) User mode. 47 (1) User mode.
45 48
@@ -47,42 +50,46 @@ The FR-V CPU has three basic operating modes. In order of increasing capability:
47 50
48 (2) Kernel mode. 51 (2) Kernel mode.
49 52
50 Normal kernel mode. There are many additional control registers available that may be 53 Normal kernel mode. There are many additional control registers
51 accessed in this mode, in addition to all the stuff available to user mode. This has two 54 available that may be accessed in this mode, in addition to all the
52 submodes: 55 stuff available to user mode. This has two submodes:
53 56
54 (a) Exceptions enabled (PSR.T == 1). 57 (a) Exceptions enabled (PSR.T == 1).
55 58
56 Exceptions will invoke the appropriate normal kernel mode handler. On entry to the 59 Exceptions will invoke the appropriate normal kernel mode
57 handler, the PSR.T bit will be cleared. 60 handler. On entry to the handler, the PSR.T bit will be cleared.
58 61
59 (b) Exceptions disabled (PSR.T == 0). 62 (b) Exceptions disabled (PSR.T == 0).
60 63
61 No exceptions or interrupts may happen. Any mandatory exceptions will cause the CPU to 64 No exceptions or interrupts may happen. Any mandatory exceptions
62 halt unless the CPU is told to jump into debug mode instead. 65 will cause the CPU to halt unless the CPU is told to jump into
66 debug mode instead.
63 67
64 (3) Debug mode. 68 (3) Debug mode.
65 69
66 No exceptions may happen in this mode. Memory protection and management exceptions will be 70 No exceptions may happen in this mode. Memory protection and
67 flagged for later consideration, but the exception handler won't be invoked. Debugging traps 71 management exceptions will be flagged for later consideration, but
68 such as hardware breakpoints and watchpoints will be ignored. This mode is entered only by 72 the exception handler won't be invoked. Debugging traps such as
69 debugging events obtained from the other two modes. 73 hardware breakpoints and watchpoints will be ignored. This mode is
74 entered only by debugging events obtained from the other two modes.
70 75
71 All kernel mode registers may be accessed, plus a few extra debugging specific registers. 76 All kernel mode registers may be accessed, plus a few extra debugging
77 specific registers.
72 78
73 79
74================================= 80=================================
75INTERNAL KERNEL-MODE REGISTER ABI 81INTERNAL KERNEL-MODE REGISTER ABI
76================================= 82=================================
77 83
78There are a number of permanent register assignments that are set up by entry.S in the exception 84There are a number of permanent register assignments that are set up by
79prologue. Note that there is a complete set of exception prologues for each of user->kernel 85entry.S in the exception prologue. Note that there is a complete set of
80transition and kernel->kernel transition. There are also user->debug and kernel->debug mode 86exception prologues for each of user->kernel transition and kernel->kernel
81transition prologues. 87transition. There are also user->debug and kernel->debug mode transition
88prologues.
82 89
83 90
84 REGISTER FLAVOUR USE 91 REGISTER FLAVOUR USE
85 =============== ======= ==================================================== 92 =============== ======= ==============================================
86 GR1 Supervisor stack pointer 93 GR1 Supervisor stack pointer
87 GR15 Current thread info pointer 94 GR15 Current thread info pointer
88 GR16 GP-Rel base register for small data 95 GR16 GP-Rel base register for small data
@@ -92,10 +99,12 @@ transition prologues.
92 GR31 NOMMU Destroyed by debug mode entry 99 GR31 NOMMU Destroyed by debug mode entry
93 GR31 MMU Destroyed by TLB miss kernel mode entry 100 GR31 MMU Destroyed by TLB miss kernel mode entry
94 CCR.ICC2 Virtual interrupt disablement tracking 101 CCR.ICC2 Virtual interrupt disablement tracking
95 CCCR.CC3 Cleared by exception prologue (atomic op emulation) 102 CCCR.CC3 Cleared by exception prologue
103 (atomic op emulation)
96 SCR0 MMU See mmu-layout.txt. 104 SCR0 MMU See mmu-layout.txt.
97 SCR1 MMU See mmu-layout.txt. 105 SCR1 MMU See mmu-layout.txt.
98 SCR2 MMU Save for EAR0 (destroyed by icache insns in debug mode) 106 SCR2 MMU Save for EAR0 (destroyed by icache insns
107 in debug mode)
99 SCR3 MMU Save for GR31 during debug exceptions 108 SCR3 MMU Save for GR31 during debug exceptions
100 DAMR/IAMR NOMMU Fixed memory protection layout. 109 DAMR/IAMR NOMMU Fixed memory protection layout.
101 DAMR/IAMR MMU See mmu-layout.txt. 110 DAMR/IAMR MMU See mmu-layout.txt.
@@ -104,18 +113,21 @@ transition prologues.
104Certain registers are also used or modified across function calls: 113Certain registers are also used or modified across function calls:
105 114
106 REGISTER CALL RETURN 115 REGISTER CALL RETURN
107 =============== =============================== =============================== 116 =============== =============================== ======================
108 GR0 Fixed Zero - 117 GR0 Fixed Zero -
109 GR2 Function call frame pointer 118 GR2 Function call frame pointer
110 GR3 Special Preserved 119 GR3 Special Preserved
111 GR3-GR7 - Clobbered 120 GR3-GR7 - Clobbered
112 GR8 Function call arg #1 Return value (or clobbered) 121 GR8 Function call arg #1 Return value
113 GR9 Function call arg #2 Return value MSW (or clobbered) 122 (or clobbered)
123 GR9 Function call arg #2 Return value MSW
124 (or clobbered)
114 GR10-GR13 Function call arg #3-#6 Clobbered 125 GR10-GR13 Function call arg #3-#6 Clobbered
115 GR14 - Clobbered 126 GR14 - Clobbered
116 GR15-GR16 Special Preserved 127 GR15-GR16 Special Preserved
117 GR17-GR27 - Preserved 128 GR17-GR27 - Preserved
118 GR28-GR31 Special Only accessed explicitly 129 GR28-GR31 Special Only accessed
130 explicitly
119 LR Return address after CALL Clobbered 131 LR Return address after CALL Clobbered
120 CCR/CCCR - Mostly Clobbered 132 CCR/CCCR - Mostly Clobbered
121 133
@@ -124,46 +136,53 @@ Certain registers are also used or modified across function calls:
124INTERNAL DEBUG-MODE REGISTER ABI 136INTERNAL DEBUG-MODE REGISTER ABI
125================================ 137================================
126 138
127This is the same as the kernel-mode register ABI for functions calls. The difference is that in 139This is the same as the kernel-mode register ABI for functions calls. The
128debug-mode there's a different stack and a different exception frame. Almost all the global 140difference is that in debug-mode there's a different stack and a different
129registers from kernel-mode (including the stack pointer) may be changed. 141exception frame. Almost all the global registers from kernel-mode
142(including the stack pointer) may be changed.
130 143
131 REGISTER FLAVOUR USE 144 REGISTER FLAVOUR USE
132 =============== ======= ==================================================== 145 =============== ======= ==============================================
133 GR1 Debug stack pointer 146 GR1 Debug stack pointer
134 GR16 GP-Rel base register for small data 147 GR16 GP-Rel base register for small data
135 GR31 Current debug exception frame pointer (__debug_frame) 148 GR31 Current debug exception frame pointer
149 (__debug_frame)
136 SCR3 MMU Saved value of GR31 150 SCR3 MMU Saved value of GR31
137 151
138 152
139Note that debug mode is able to interfere with the kernel's emulated atomic ops, so it must be 153Note that debug mode is able to interfere with the kernel's emulated atomic
140exceedingly careful not to do any that would interact with the main kernel in this regard. Hence 154ops, so it must be exceedingly careful not to do any that would interact
141the debug mode code (gdbstub) is almost completely self-contained. The only external code used is 155with the main kernel in this regard. Hence the debug mode code (gdbstub) is
142the sprintf family of functions. 156almost completely self-contained. The only external code used is the
157sprintf family of functions.
143 158
144Futhermore, break.S is so complicated because single-step mode does not switch off on entry to an 159Futhermore, break.S is so complicated because single-step mode does not
145exception. That means unless manually disabled, single-stepping will blithely go on stepping into 160switch off on entry to an exception. That means unless manually disabled,
146things like interrupts. See gdbstub.txt for more information. 161single-stepping will blithely go on stepping into things like interrupts.
162See gdbstub.txt for more information.
147 163
148 164
149========================== 165==========================
150VIRTUAL INTERRUPT HANDLING 166VIRTUAL INTERRUPT HANDLING
151========================== 167==========================
152 168
153Because accesses to the PSR is so slow, and to disable interrupts we have to access it twice (once 169Because accesses to the PSR is so slow, and to disable interrupts we have
154to read and once to write), we don't actually disable interrupts at all if we don't have to. What 170to access it twice (once to read and once to write), we don't actually
155we do instead is use the ICC2 condition code flags to note virtual disablement, such that if we 171disable interrupts at all if we don't have to. What we do instead is use
156then do take an interrupt, we note the flag, really disable interrupts, set another flag and resume 172the ICC2 condition code flags to note virtual disablement, such that if we
157execution at the point the interrupt happened. Setting condition flags as a side effect of an 173then do take an interrupt, we note the flag, really disable interrupts, set
158arithmetic or logical instruction is really fast. This use of the ICC2 only occurs within the 174another flag and resume execution at the point the interrupt happened.
175Setting condition flags as a side effect of an arithmetic or logical
176instruction is really fast. This use of the ICC2 only occurs within the
159kernel - it does not affect userspace. 177kernel - it does not affect userspace.
160 178
161The flags we use are: 179The flags we use are:
162 180
163 (*) CCR.ICC2.Z [Zero flag] 181 (*) CCR.ICC2.Z [Zero flag]
164 182
165 Set to virtually disable interrupts, clear when interrupts are virtually enabled. Can be 183 Set to virtually disable interrupts, clear when interrupts are
166 modified by logical instructions without affecting the Carry flag. 184 virtually enabled. Can be modified by logical instructions without
185 affecting the Carry flag.
167 186
168 (*) CCR.ICC2.C [Carry flag] 187 (*) CCR.ICC2.C [Carry flag]
169 188
@@ -176,8 +195,9 @@ What happens is this:
176 195
177 ICC2.Z is 0, ICC2.C is 1. 196 ICC2.Z is 0, ICC2.C is 1.
178 197
179 (2) An interrupt occurs. The exception prologue examines ICC2.Z and determines that nothing needs 198 (2) An interrupt occurs. The exception prologue examines ICC2.Z and
180 doing. This is done simply with an unlikely BEQ instruction. 199 determines that nothing needs doing. This is done simply with an
200 unlikely BEQ instruction.
181 201
182 (3) The interrupts are disabled (local_irq_disable) 202 (3) The interrupts are disabled (local_irq_disable)
183 203
@@ -187,48 +207,56 @@ What happens is this:
187 207
188 ICC2.Z would be set to 0. 208 ICC2.Z would be set to 0.
189 209
190 A TIHI #2 instruction (trap #2 if condition HI - Z==0 && C==0) would be used to trap if 210 A TIHI #2 instruction (trap #2 if condition HI - Z==0 && C==0) would
191 interrupts were now virtually enabled, but physically disabled - which they're not, so the 211 be used to trap if interrupts were now virtually enabled, but
192 trap isn't taken. The kernel would then be back to state (1). 212 physically disabled - which they're not, so the trap isn't taken. The
213 kernel would then be back to state (1).
193 214
194 (5) An interrupt occurs. The exception prologue examines ICC2.Z and determines that the interrupt 215 (5) An interrupt occurs. The exception prologue examines ICC2.Z and
195 shouldn't actually have happened. It jumps aside, and there disabled interrupts by setting 216 determines that the interrupt shouldn't actually have happened. It
196 PSR.PIL to 14 and then it clears ICC2.C. 217 jumps aside, and there disabled interrupts by setting PSR.PIL to 14
218 and then it clears ICC2.C.
197 219
198 (6) If interrupts were then saved and disabled again (local_irq_save): 220 (6) If interrupts were then saved and disabled again (local_irq_save):
199 221
200 ICC2.Z would be shifted into the save variable and masked off (giving a 1). 222 ICC2.Z would be shifted into the save variable and masked off
223 (giving a 1).
201 224
202 ICC2.Z would then be set to 1 (thus unchanged), and ICC2.C would be unaffected (ie: 0). 225 ICC2.Z would then be set to 1 (thus unchanged), and ICC2.C would be
226 unaffected (ie: 0).
203 227
204 (7) If interrupts were then restored from state (6) (local_irq_restore): 228 (7) If interrupts were then restored from state (6) (local_irq_restore):
205 229
206 ICC2.Z would be set to indicate the result of XOR'ing the saved value (ie: 1) with 1, which 230 ICC2.Z would be set to indicate the result of XOR'ing the saved
207 gives a result of 0 - thus leaving ICC2.Z set. 231 value (ie: 1) with 1, which gives a result of 0 - thus leaving
232 ICC2.Z set.
208 233
209 ICC2.C would remain unaffected (ie: 0). 234 ICC2.C would remain unaffected (ie: 0).
210 235
211 A TIHI #2 instruction would be used to again assay the current state, but this would do 236 A TIHI #2 instruction would be used to again assay the current state,
212 nothing as Z==1. 237 but this would do nothing as Z==1.
213 238
214 (8) If interrupts were then enabled (local_irq_enable): 239 (8) If interrupts were then enabled (local_irq_enable):
215 240
216 ICC2.Z would be cleared. ICC2.C would be left unaffected. Both flags would now be 0. 241 ICC2.Z would be cleared. ICC2.C would be left unaffected. Both
242 flags would now be 0.
217 243
218 A TIHI #2 instruction again issued to assay the current state would then trap as both Z==0 244 A TIHI #2 instruction again issued to assay the current state would
219 [interrupts virtually enabled] and C==0 [interrupts really disabled] would then be true. 245 then trap as both Z==0 [interrupts virtually enabled] and C==0
246 [interrupts really disabled] would then be true.
220 247
221 (9) The trap #2 handler would simply enable hardware interrupts (set PSR.PIL to 0), set ICC2.C to 248 (9) The trap #2 handler would simply enable hardware interrupts
222 1 and return. 249 (set PSR.PIL to 0), set ICC2.C to 1 and return.
223 250
224(10) Immediately upon returning, the pending interrupt would be taken. 251(10) Immediately upon returning, the pending interrupt would be taken.
225 252
226(11) The interrupt handler would take the path of actually processing the interrupt (ICC2.Z is 253(11) The interrupt handler would take the path of actually processing the
227 clear, BEQ fails as per step (2)). 254 interrupt (ICC2.Z is clear, BEQ fails as per step (2)).
228 255
229(12) The interrupt handler would then set ICC2.C to 1 since hardware interrupts are definitely 256(12) The interrupt handler would then set ICC2.C to 1 since hardware
230 enabled - or else the kernel wouldn't be here. 257 interrupts are definitely enabled - or else the kernel wouldn't be here.
231 258
232(13) On return from the interrupt handler, things would be back to state (1). 259(13) On return from the interrupt handler, things would be back to state (1).
233 260
234This trap (#2) is only available in kernel mode. In user mode it will result in SIGILL. 261This trap (#2) is only available in kernel mode. In user mode it will
262result in SIGILL.
diff --git a/Documentation/i2c/busses/i2c-parport b/Documentation/i2c/busses/i2c-parport
index d9f23c0763f1..77b995dfca22 100644
--- a/Documentation/i2c/busses/i2c-parport
+++ b/Documentation/i2c/busses/i2c-parport
@@ -12,18 +12,22 @@ meant as a replacement for the older, individual drivers:
12 teletext adapters) 12 teletext adapters)
13 13
14It currently supports the following devices: 14It currently supports the following devices:
15 * Philips adapter 15 * (type=0) Philips adapter
16 * home brew teletext adapter 16 * (type=1) home brew teletext adapter
17 * Velleman K8000 adapter 17 * (type=2) Velleman K8000 adapter
18 * ELV adapter 18 * (type=3) ELV adapter
19 * Analog Devices evaluation boards (ADM1025, ADM1030, ADM1031, ADM1032) 19 * (type=4) Analog Devices ADM1032 evaluation board
20 * Barco LPT->DVI (K5800236) adapter 20 * (type=5) Analog Devices evaluation boards: ADM1025, ADM1030, ADM1031
21 * (type=6) Barco LPT->DVI (K5800236) adapter
21 22
22These devices use different pinout configurations, so you have to tell 23These devices use different pinout configurations, so you have to tell
23the driver what you have, using the type module parameter. There is no 24the driver what you have, using the type module parameter. There is no
24way to autodetect the devices. Support for different pinout configurations 25way to autodetect the devices. Support for different pinout configurations
25can be easily added when needed. 26can be easily added when needed.
26 27
28Earlier kernels defaulted to type=0 (Philips). But now, if the type
29parameter is missing, the driver will simply fail to initialize.
30
27 31
28Building your own adapter 32Building your own adapter
29------------------------- 33-------------------------
diff --git a/Documentation/input/joystick-parport.txt b/Documentation/input/joystick-parport.txt
index 88a011c9f985..d537c48cc6d0 100644
--- a/Documentation/input/joystick-parport.txt
+++ b/Documentation/input/joystick-parport.txt
@@ -36,12 +36,12 @@ with them.
36 36
37 All NES and SNES use the same synchronous serial protocol, clocked from 37 All NES and SNES use the same synchronous serial protocol, clocked from
38the computer's side (and thus timing insensitive). To allow up to 5 NES 38the computer's side (and thus timing insensitive). To allow up to 5 NES
39and/or SNES gamepads connected to the parallel port at once, the output 39and/or SNES gamepads and/or SNES mice connected to the parallel port at once,
40lines of the parallel port are shared, while one of 5 available input lines 40the output lines of the parallel port are shared, while one of 5 available
41is assigned to each gamepad. 41input lines is assigned to each gamepad.
42 42
43 This protocol is handled by the gamecon.c driver, so that's the one 43 This protocol is handled by the gamecon.c driver, so that's the one
44you'll use for NES and SNES gamepads. 44you'll use for NES, SNES gamepads and SNES mice.
45 45
46 The main problem with PC parallel ports is that they don't have +5V power 46 The main problem with PC parallel ports is that they don't have +5V power
47source on any of their pins. So, if you want a reliable source of power 47source on any of their pins. So, if you want a reliable source of power
@@ -106,7 +106,7 @@ A, Turbo B, Select and Start, and is connected through 5 wires, then it is
106either a NES or NES clone and will work with this connection. SNES gamepads 106either a NES or NES clone and will work with this connection. SNES gamepads
107also use 5 wires, but have more buttons. They will work as well, of course. 107also use 5 wires, but have more buttons. They will work as well, of course.
108 108
109Pinout for NES gamepads Pinout for SNES gamepads 109Pinout for NES gamepads Pinout for SNES gamepads and mice
110 110
111 +----> Power +-----------------------\ 111 +----> Power +-----------------------\
112 | 7 | o o o o | x x o | 1 112 | 7 | o o o o | x x o | 1
@@ -454,6 +454,7 @@ uses the following kernel/module command line:
454 6 | N64 pad 454 6 | N64 pad
455 7 | Sony PSX controller 455 7 | Sony PSX controller
456 8 | Sony PSX DDR controller 456 8 | Sony PSX DDR controller
457 9 | SNES mouse
457 458
458 The exact type of the PSX controller type is autoprobed when used so 459 The exact type of the PSX controller type is autoprobed when used so
459hot swapping should work (but is not recomended). 460hot swapping should work (but is not recomended).
diff --git a/Documentation/isdn/README.gigaset b/Documentation/isdn/README.gigaset
new file mode 100644
index 000000000000..85a64defd385
--- /dev/null
+++ b/Documentation/isdn/README.gigaset
@@ -0,0 +1,286 @@
1GigaSet 307x Device Driver
2==========================
3
41. Requirements
5 ------------
61.1. Hardware
7 --------
8 This release supports the connection of the Gigaset 307x/417x family of
9 ISDN DECT bases via Gigaset M101 Data, Gigaset M105 Data or direct USB
10 connection. The following devices are reported to be compatible:
11 307x/417x:
12 Gigaset SX255isdn
13 Gigaset SX353isdn
14 Sinus 45 [AB] isdn (Deutsche Telekom)
15 Sinus 721X/XA
16 Vox Chicago 390 ISDN (KPN Telecom)
17 M101:
18 Sinus 45 Data 1 (Telekom)
19 M105:
20 Gigaset USB Adapter DECT
21 Sinus 45 Data 2 (Telekom)
22 Sinus 721 data
23 Chicago 390 USB (KPN)
24 See also http://www.erbze.info/sinus_gigaset.htm and
25 http://gigaset307x.sourceforge.net/
26
27 We had also reports from users of Gigaset M105 who could use the drivers
28 with SX 100 and CX 100 ISDN bases (only in unimodem mode, see section 2.4.)
29 If you have another device that works with our driver, please let us know.
30 For example, Gigaset SX205isdn/Sinus 721 X SE and Gigaset SX303isdn bases
31 are just versions without answering machine of models known to work, so
32 they should work just as well; but so far we are lacking positive reports
33 on these.
34
35 Chances of getting an USB device to work are good if the output of
36 lsusb
37 at the command line contains one of the following:
38 ID 0681:0001
39 ID 0681:0002
40 ID 0681:0009
41 ID 0681:0021
42 ID 0681:0022
43
441.2. Software
45 --------
46 The driver works with ISDN4linux and so can be used with any software
47 which is able to use ISDN4linux for ISDN connections (voice or data).
48 CAPI4Linux support is planned but not yet available.
49
50 There are some user space tools available at
51 http://sourceforge.net/projects/gigaset307x/
52 which provide access to additional device specific functions like SMS,
53 phonebook or call journal.
54
55
562. How to use the driver
57 ---------------------
582.1. Modules
59 -------
60 To get the device working, you have to load the proper kernel module. You
61 can do this using
62 modprobe modulename
63 where modulename is usb_gigaset (M105) or bas_gigaset (direct USB
64 connection to the base).
65
662.2. Device nodes for user space programs
67 ------------------------------------
68 The device can be accessed from user space (eg. by the user space tools
69 mentioned in 1.2.) through the device nodes:
70
71 - /dev/ttyGU0 for M105 (USB data boxes)
72 - /dev/ttyGB0 for the base driver (direct USB connection)
73
74 You can also select a "default device" which is used by the frontends when
75 no device node is given as parameter, by creating a symlink /dev/ttyG to
76 one of them, eg.:
77
78 ln -s /dev/ttyGB0 /dev/ttyG
79
802.3. ISDN4linux
81 ----------
82 This is the "normal" mode of operation. After loading the module you can
83 set up the ISDN system just as you'd do with any ISDN card.
84 Your distribution should provide some configuration utility.
85 If not, you can use some HOWTOs like
86 http://www.linuxhaven.de/dlhp/HOWTO/DE-ISDN-HOWTO-5.html
87 If this doesn't work, because you have some recent device like SX100 where
88 debug output (see section 3.2.) shows something like this when dialing
89 CMD Received: ERROR
90 Available Params: 0
91 Connection State: 0, Response: -1
92 gigaset_process_response: resp_code -1 in ConState 0 !
93 Timeout occurred
94 you might need to use unimodem mode:
95
962.4. Unimodem mode
97 -------------
98 This is needed for some devices [e.g. SX100] as they have problems with
99 the "normal" commands.
100
101 If you have installed the command line tool gigacontr, you can enter
102 unimodem mode using
103 gigacontr --mode unimodem
104 You can switch back using
105 gigacontr --mode isdn
106
107 You can also load the driver using e.g.
108 modprobe usb_gigaset startmode=0
109 to prevent the driver from starting in "isdn4linux mode".
110
111 In this mode the device works like a modem connected to a serial port
112 (the /dev/ttyGU0, ... mentioned above) which understands the commands
113 ATZ init, reset
114 => OK or ERROR
115 ATD
116 ATDT dial
117 => OK, CONNECT,
118 BUSY,
119 NO DIAL TONE,
120 NO CARRIER,
121 NO ANSWER
122 <pause>+++<pause> change to command mode when connected
123 ATH hangup
124
125 You can use some configuration tool of your distribution to configure this
126 "modem" or configure pppd/wvdial manually. There are some example ppp
127 configuration files and chat scripts in the gigaset-VERSION/ppp directory.
128 Please note that the USB drivers are not able to change the state of the
129 control lines (the M105 driver can be configured to use some undocumented
130 control requests, if you really need the control lines, though). This means
131 you must use "Stupid Mode" if you are using wvdial or you should use the
132 nocrtscts option of pppd.
133 You must also assure that the ppp_async module is loaded with the parameter
134 flag_time=0. You can do this e.g. by adding a line like
135
136 options ppp_async flag_time=0
137
138 to /etc/modprobe.conf. If your distribution has some local module
139 configuration file like /etc/modprobe.conf.local,
140 using that should be preferred.
141
1422.5. Call-ID (CID) mode
143 ------------------
144 Call-IDs are numbers used to tag commands to, and responses from, the
145 Gigaset base in order to support the simultaneous handling of multiple
146 ISDN calls. Their use can be enabled ("CID mode") or disabled ("Unimodem
147 mode"). Without Call-IDs (in Unimodem mode), only a very limited set of
148 functions is available. It allows outgoing data connections only, but
149 does not signal incoming calls or other base events.
150
151 DECT cordless data devices (M10x) permanently occupy the cordless
152 connection to the base while Call-IDs are activated. As the Gigaset
153 bases only support one DECT data connection at a time, this prevents
154 other DECT cordless data devices from accessing the base.
155
156 During active operation, the driver switches to the necessary mode
157 automatically. However, for the reasons above, the mode chosen when
158 the device is not in use (idle) can be selected by the user.
159 - If you want to receive incoming calls, you can use the default
160 settings (CID mode).
161 - If you have several DECT data devices (M10x) which you want to use
162 in turn, select Unimodem mode by passing the parameter "cidmode=0" to
163 the driver ("modprobe usb_gigaset cidmode=0" or modprobe.conf).
164
165 If you want both of these at once, you are out of luck.
166
167 You can also use /sys/module/<name>/parameters/cidmode for changing
168 the CID mode setting (<name> is usb_gigaset or bas_gigaset).
169
170
1713. Troubleshooting
172 ---------------
1733.1. Solutions to frequently reported problems
174 -----------------------------------------
175 Problem:
176 You have a slow provider and isdn4linux gives up dialing too early.
177 Solution:
178 Load the isdn module using the dialtimeout option. You can do this e.g.
179 by adding a line like
180
181 options isdn dialtimeout=15
182
183 to /etc/modprobe.conf. If your distribution has some local module
184 configuration file like /etc/modprobe.conf.local,
185 using that should be preferred.
186
187 Problem:
188 Your isdn script aborts with a message about isdnlog.
189 Solution:
190 Try deactivating (or commenting out) isdnlog. This driver does not
191 support it.
192
193 Problem:
194 You have two or more DECT data adapters (M101/M105) and only the
195 first one you turn on works.
196 Solution:
197 Select Unimodem mode for all DECT data adapters. (see section 2.4.)
198
1993.2. Telling the driver to provide more information
200 ----------------------------------------------
201 Building the driver with the "Gigaset debugging" kernel configuration
202 option (CONFIG_GIGASET_DEBUG) gives it the ability to produce additional
203 information useful for debugging.
204
205 You can control the amount of debugging information the driver produces by
206 writing an appropriate value to /sys/module/gigaset/parameters/debug, e.g.
207 echo 0 > /sys/module/gigaset/parameters/debug
208 switches off debugging output completely,
209 echo 0x10a020 > /sys/module/gigaset/parameters/debug
210 enables the standard set of debugging output messages. These values are
211 bit patterns where every bit controls a certain type of debugging output.
212 See the constants DEBUG_* in the source file gigaset.h for details.
213
214 The initial value can be set using the debug parameter when loading the
215 module "gigaset", e.g. by adding a line
216 options gigaset debug=0
217 to /etc/modprobe.conf, ...
218
219 Generated debugging information can be found
220 - as output of the command
221 dmesg
222 - in system log files written by your syslog daemon, usually
223 in /var/log/, e.g. /var/log/messages.
224
2253.3. Reporting problems and bugs
226 ---------------------------
227 If you can't solve problems with the driver on your own, feel free to
228 use one of the forums, bug trackers, or mailing lists on
229 http://sourceforge.net/projects/gigaset307x
230 or write an electronic mail to the maintainers.
231
232 Try to provide as much information as possible, such as
233 - distribution
234 - kernel version (uname -r)
235 - gcc version (gcc --version)
236 - hardware architecture (uname -m, ...)
237 - type and firmware version of your device (base and wireless module,
238 if any)
239 - output of "lsusb -v" (if using an USB device)
240 - error messages
241 - relevant system log messages (it would help if you activate debug
242 output as described in 3.2.)
243
244 For help with general configuration problems not specific to our driver,
245 such as isdn4linux and network configuration issues, please refer to the
246 appropriate forums and newsgroups.
247
2483.4. Reporting problem solutions
249 ---------------------------
250 If you solved a problem with our drivers, wrote startup scripts for your
251 distribution, ... feel free to contact us (using one of the places
252 mentioned in 3.3.). We'd like to add scripts, hints, documentation
253 to the driver and/or the project web page.
254
255
2564. Links, other software
257 ---------------------
258 - Sourceforge project developing this driver and associated tools
259 http://sourceforge.net/projects/gigaset307x
260 - Yahoo! Group on the Siemens Gigaset family of devices
261 http://de.groups.yahoo.com/group/Siemens-Gigaset
262 - Siemens Gigaset/T-Sinus compatibility table
263 http://www.erbze.info/sinus_gigaset.htm
264
265
2665. Credits
267 -------
268 Thanks to
269
270 Karsten Keil
271 for his help with isdn4linux
272 Deti Fliegl
273 for his base driver code
274 Dennis Dietrich
275 for his kernel 2.6 patches
276 Andreas Rummel
277 for his work and logs to get unimodem mode working
278 Andreas Degert
279 for his logs and patches to get cx 100 working
280 Dietrich Feist
281 for his generous donation of one M105 and two M101 cordless adapters
282 Christoph Schweers
283 for his generous donation of a M34 device
284
285 and all the other people who sent logs and other information.
286
diff --git a/Documentation/kbuild/modules.txt b/Documentation/kbuild/modules.txt
index fcccf2432f98..61fc079eb966 100644
--- a/Documentation/kbuild/modules.txt
+++ b/Documentation/kbuild/modules.txt
@@ -44,7 +44,7 @@ What is covered within this file is mainly information to authors
44of modules. The author of an external modules should supply 44of modules. The author of an external modules should supply
45a makefile that hides most of the complexity so one only has to type 45a makefile that hides most of the complexity so one only has to type
46'make' to build the module. A complete example will be present in 46'make' to build the module. A complete example will be present in
47chapter ¤. Creating a kbuild file for an external module". 47chapter 4, "Creating a kbuild file for an external module".
48 48
49 49
50=== 2. How to build external modules 50=== 2. How to build external modules
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index f8cb55c30b0f..b3a6187e5305 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1,4 +1,4 @@
1February 2003 Kernel Parameters v2.5.59 1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~ 2 ~~~~~~~~~~~~~~~~~
3 3
4The following is a consolidated list of the kernel parameters as implemented 4The following is a consolidated list of the kernel parameters as implemented
@@ -17,9 +17,17 @@ are specified on the kernel command line with the module name plus
17 17
18 usbcore.blinkenlights=1 18 usbcore.blinkenlights=1
19 19
20The text in square brackets at the beginning of the description states the 20This document may not be entirely up to date and comprehensive. The command
21restrictions on the kernel for the said kernel parameter to be valid. The 21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22restrictions referred to are that the relevant option is valid if: 22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
27The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
23 31
24 ACPI ACPI support is enabled. 32 ACPI ACPI support is enabled.
25 ALSA ALSA sound support is enabled. 33 ALSA ALSA sound support is enabled.
@@ -1046,10 +1054,10 @@ running once the system is up.
1046 noltlbs [PPC] Do not use large page/tlb entries for kernel 1054 noltlbs [PPC] Do not use large page/tlb entries for kernel
1047 lowmem mapping on PPC40x. 1055 lowmem mapping on PPC40x.
1048 1056
1049 nomce [IA-32] Machine Check Exception
1050
1051 nomca [IA-64] Disable machine check abort handling 1057 nomca [IA-64] Disable machine check abort handling
1052 1058
1059 nomce [IA-32] Machine Check Exception
1060
1053 noresidual [PPC] Don't use residual data on PReP machines. 1061 noresidual [PPC] Don't use residual data on PReP machines.
1054 1062
1055 noresume [SWSUSP] Disables resume and restores original swap 1063 noresume [SWSUSP] Disables resume and restores original swap
@@ -1682,20 +1690,6 @@ running once the system is up.
1682 1690
1683 1691
1684______________________________________________________________________ 1692______________________________________________________________________
1685Changelog:
1686
16872000-06-?? Mr. Unknown
1688 The last known update (for 2.4.0) - the changelog was not kept before.
1689
16902002-11-24 Petr Baudis <pasky@ucw.cz>
1691 Randy Dunlap <randy.dunlap@verizon.net>
1692 Update for 2.5.49, description for most of the options introduced,
1693 references to other documentation (C files, READMEs, ..), added S390,
1694 PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
1695 reformatting.
1696
16972005-10-19 Randy Dunlap <rdunlap@xenotime.net>
1698 Lots of typos, whitespace, some reformatting.
1699 1693
1700TODO: 1694TODO:
1701 1695
diff --git a/Documentation/laptop-mode.txt b/Documentation/laptop-mode.txt
index b18e21675906..5696e879449b 100644
--- a/Documentation/laptop-mode.txt
+++ b/Documentation/laptop-mode.txt
@@ -919,11 +919,11 @@ int main(int argc, char **argv)
919 int settle_time = 60; 919 int settle_time = 60;
920 920
921 /* Parse the simple command-line */ 921 /* Parse the simple command-line */
922 if (ac == 2) 922 if (argc == 2)
923 disk = av[1]; 923 disk = argv[1];
924 else if (ac == 4) { 924 else if (argc == 4) {
925 settle_time = atoi(av[2]); 925 settle_time = atoi(argv[2]);
926 disk = av[3]; 926 disk = argv[3];
927 } else 927 } else
928 usage(); 928 usage();
929 929
diff --git a/Documentation/leds-class.txt b/Documentation/leds-class.txt
new file mode 100644
index 000000000000..8c35c0426110
--- /dev/null
+++ b/Documentation/leds-class.txt
@@ -0,0 +1,71 @@
1LED handling under Linux
2========================
3
4If you're reading this and thinking about keyboard leds, these are
5handled by the input subsystem and the led class is *not* needed.
6
7In its simplest form, the LED class just allows control of LEDs from
8userspace. LEDs appear in /sys/class/leds/. The brightness file will
9set the brightness of the LED (taking a value 0-255). Most LEDs don't
10have hardware brightness support so will just be turned on for non-zero
11brightness settings.
12
13The class also introduces the optional concept of an LED trigger. A trigger
14is a kernel based source of led events. Triggers can either be simple or
15complex. A simple trigger isn't configurable and is designed to slot into
16existing subsystems with minimal additional code. Examples are the ide-disk,
17nand-disk and sharpsl-charge triggers. With led triggers disabled, the code
18optimises away.
19
20Complex triggers whilst available to all LEDs have LED specific
21parameters and work on a per LED basis. The timer trigger is an example.
22
23You can change triggers in a similar manner to the way an IO scheduler
24is chosen (via /sys/class/leds/<device>/trigger). Trigger specific
25parameters can appear in /sys/class/leds/<device> once a given trigger is
26selected.
27
28
29Design Philosophy
30=================
31
32The underlying design philosophy is simplicity. LEDs are simple devices
33and the aim is to keep a small amount of code giving as much functionality
34as possible. Please keep this in mind when suggesting enhancements.
35
36
37LED Device Naming
38=================
39
40Is currently of the form:
41
42"devicename:colour"
43
44There have been calls for LED properties such as colour to be exported as
45individual led class attributes. As a solution which doesn't incur as much
46overhead, I suggest these become part of the device name. The naming scheme
47above leaves scope for further attributes should they be needed.
48
49
50Known Issues
51============
52
53The LED Trigger core cannot be a module as the simple trigger functions
54would cause nightmare dependency issues. I see this as a minor issue
55compared to the benefits the simple trigger functionality brings. The
56rest of the LED subsystem can be modular.
57
58Some leds can be programmed to flash in hardware. As this isn't a generic
59LED device property, this should be exported as a device specific sysfs
60attribute rather than part of the class if this functionality is required.
61
62
63Future Development
64==================
65
66At the moment, a trigger can't be created specifically for a single LED.
67There are a number of cases where a trigger might only be mappable to a
68particular LED (ACPI?). The addition of triggers provided by the LED driver
69should cover this option and be possible to add without breaking the
70current interface.
71
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
new file mode 100644
index 000000000000..92f0056d928c
--- /dev/null
+++ b/Documentation/memory-barriers.txt
@@ -0,0 +1,1941 @@
1 ============================
2 LINUX KERNEL MEMORY BARRIERS
3 ============================
4
5By: David Howells <dhowells@redhat.com>
6
7Contents:
8
9 (*) Abstract memory access model.
10
11 - Device operations.
12 - Guarantees.
13
14 (*) What are memory barriers?
15
16 - Varieties of memory barrier.
17 - What may not be assumed about memory barriers?
18 - Data dependency barriers.
19 - Control dependencies.
20 - SMP barrier pairing.
21 - Examples of memory barrier sequences.
22
23 (*) Explicit kernel barriers.
24
25 - Compiler barrier.
26 - The CPU memory barriers.
27 - MMIO write barrier.
28
29 (*) Implicit kernel memory barriers.
30
31 - Locking functions.
32 - Interrupt disabling functions.
33 - Miscellaneous functions.
34
35 (*) Inter-CPU locking barrier effects.
36
37 - Locks vs memory accesses.
38 - Locks vs I/O accesses.
39
40 (*) Where are memory barriers needed?
41
42 - Interprocessor interaction.
43 - Atomic operations.
44 - Accessing devices.
45 - Interrupts.
46
47 (*) Kernel I/O barrier effects.
48
49 (*) Assumed minimum execution ordering model.
50
51 (*) The effects of the cpu cache.
52
53 - Cache coherency.
54 - Cache coherency vs DMA.
55 - Cache coherency vs MMIO.
56
57 (*) The things CPUs get up to.
58
59 - And then there's the Alpha.
60
61 (*) References.
62
63
64============================
65ABSTRACT MEMORY ACCESS MODEL
66============================
67
68Consider the following abstract model of the system:
69
70 : :
71 : :
72 : :
73 +-------+ : +--------+ : +-------+
74 | | : | | : | |
75 | | : | | : | |
76 | CPU 1 |<----->| Memory |<----->| CPU 2 |
77 | | : | | : | |
78 | | : | | : | |
79 +-------+ : +--------+ : +-------+
80 ^ : ^ : ^
81 | : | : |
82 | : | : |
83 | : v : |
84 | : +--------+ : |
85 | : | | : |
86 | : | | : |
87 +---------->| Device |<----------+
88 : | | :
89 : | | :
90 : +--------+ :
91 : :
92
93Each CPU executes a program that generates memory access operations. In the
94abstract CPU, memory operation ordering is very relaxed, and a CPU may actually
95perform the memory operations in any order it likes, provided program causality
96appears to be maintained. Similarly, the compiler may also arrange the
97instructions it emits in any order it likes, provided it doesn't affect the
98apparent operation of the program.
99
100So in the above diagram, the effects of the memory operations performed by a
101CPU are perceived by the rest of the system as the operations cross the
102interface between the CPU and rest of the system (the dotted lines).
103
104
105For example, consider the following sequence of events:
106
107 CPU 1 CPU 2
108 =============== ===============
109 { A == 1; B == 2 }
110 A = 3; x = A;
111 B = 4; y = B;
112
113The set of accesses as seen by the memory system in the middle can be arranged
114in 24 different combinations:
115
116 STORE A=3, STORE B=4, x=LOAD A->3, y=LOAD B->4
117 STORE A=3, STORE B=4, y=LOAD B->4, x=LOAD A->3
118 STORE A=3, x=LOAD A->3, STORE B=4, y=LOAD B->4
119 STORE A=3, x=LOAD A->3, y=LOAD B->2, STORE B=4
120 STORE A=3, y=LOAD B->2, STORE B=4, x=LOAD A->3
121 STORE A=3, y=LOAD B->2, x=LOAD A->3, STORE B=4
122 STORE B=4, STORE A=3, x=LOAD A->3, y=LOAD B->4
123 STORE B=4, ...
124 ...
125
126and can thus result in four different combinations of values:
127
128 x == 1, y == 2
129 x == 1, y == 4
130 x == 3, y == 2
131 x == 3, y == 4
132
133
134Furthermore, the stores committed by a CPU to the memory system may not be
135perceived by the loads made by another CPU in the same order as the stores were
136committed.
137
138
139As a further example, consider this sequence of events:
140
141 CPU 1 CPU 2
142 =============== ===============
143 { A == 1, B == 2, C = 3, P == &A, Q == &C }
144 B = 4; Q = P;
145 P = &B D = *Q;
146
147There is an obvious data dependency here, as the value loaded into D depends on
148the address retrieved from P by CPU 2. At the end of the sequence, any of the
149following results are possible:
150
151 (Q == &A) and (D == 1)
152 (Q == &B) and (D == 2)
153 (Q == &B) and (D == 4)
154
155Note that CPU 2 will never try and load C into D because the CPU will load P
156into Q before issuing the load of *Q.
157
158
159DEVICE OPERATIONS
160-----------------
161
162Some devices present their control interfaces as collections of memory
163locations, but the order in which the control registers are accessed is very
164important. For instance, imagine an ethernet card with a set of internal
165registers that are accessed through an address port register (A) and a data
166port register (D). To read internal register 5, the following code might then
167be used:
168
169 *A = 5;
170 x = *D;
171
172but this might show up as either of the following two sequences:
173
174 STORE *A = 5, x = LOAD *D
175 x = LOAD *D, STORE *A = 5
176
177the second of which will almost certainly result in a malfunction, since it set
178the address _after_ attempting to read the register.
179
180
181GUARANTEES
182----------
183
184There are some minimal guarantees that may be expected of a CPU:
185
186 (*) On any given CPU, dependent memory accesses will be issued in order, with
187 respect to itself. This means that for:
188
189 Q = P; D = *Q;
190
191 the CPU will issue the following memory operations:
192
193 Q = LOAD P, D = LOAD *Q
194
195 and always in that order.
196
197 (*) Overlapping loads and stores within a particular CPU will appear to be
198 ordered within that CPU. This means that for:
199
200 a = *X; *X = b;
201
202 the CPU will only issue the following sequence of memory operations:
203
204 a = LOAD *X, STORE *X = b
205
206 And for:
207
208 *X = c; d = *X;
209
210 the CPU will only issue:
211
212 STORE *X = c, d = LOAD *X
213
214 (Loads and stores overlap if they are targetted at overlapping pieces of
215 memory).
216
217And there are a number of things that _must_ or _must_not_ be assumed:
218
219 (*) It _must_not_ be assumed that independent loads and stores will be issued
220 in the order given. This means that for:
221
222 X = *A; Y = *B; *D = Z;
223
224 we may get any of the following sequences:
225
226 X = LOAD *A, Y = LOAD *B, STORE *D = Z
227 X = LOAD *A, STORE *D = Z, Y = LOAD *B
228 Y = LOAD *B, X = LOAD *A, STORE *D = Z
229 Y = LOAD *B, STORE *D = Z, X = LOAD *A
230 STORE *D = Z, X = LOAD *A, Y = LOAD *B
231 STORE *D = Z, Y = LOAD *B, X = LOAD *A
232
233 (*) It _must_ be assumed that overlapping memory accesses may be merged or
234 discarded. This means that for:
235
236 X = *A; Y = *(A + 4);
237
238 we may get any one of the following sequences:
239
240 X = LOAD *A; Y = LOAD *(A + 4);
241 Y = LOAD *(A + 4); X = LOAD *A;
242 {X, Y} = LOAD {*A, *(A + 4) };
243
244 And for:
245
246 *A = X; Y = *A;
247
248 we may get either of:
249
250 STORE *A = X; Y = LOAD *A;
251 STORE *A = Y;
252
253
254=========================
255WHAT ARE MEMORY BARRIERS?
256=========================
257
258As can be seen above, independent memory operations are effectively performed
259in random order, but this can be a problem for CPU-CPU interaction and for I/O.
260What is required is some way of intervening to instruct the compiler and the
261CPU to restrict the order.
262
263Memory barriers are such interventions. They impose a perceived partial
264ordering between the memory operations specified on either side of the barrier.
265They request that the sequence of memory events generated appears to other
266parts of the system as if the barrier is effective on that CPU.
267
268
269VARIETIES OF MEMORY BARRIER
270---------------------------
271
272Memory barriers come in four basic varieties:
273
274 (1) Write (or store) memory barriers.
275
276 A write memory barrier gives a guarantee that all the STORE operations
277 specified before the barrier will appear to happen before all the STORE
278 operations specified after the barrier with respect to the other
279 components of the system.
280
281 A write barrier is a partial ordering on stores only; it is not required
282 to have any effect on loads.
283
284 A CPU can be viewed as as commiting a sequence of store operations to the
285 memory system as time progresses. All stores before a write barrier will
286 occur in the sequence _before_ all the stores after the write barrier.
287
288 [!] Note that write barriers should normally be paired with read or data
289 dependency barriers; see the "SMP barrier pairing" subsection.
290
291
292 (2) Data dependency barriers.
293
294 A data dependency barrier is a weaker form of read barrier. In the case
295 where two loads are performed such that the second depends on the result
296 of the first (eg: the first load retrieves the address to which the second
297 load will be directed), a data dependency barrier would be required to
298 make sure that the target of the second load is updated before the address
299 obtained by the first load is accessed.
300
301 A data dependency barrier is a partial ordering on interdependent loads
302 only; it is not required to have any effect on stores, independent loads
303 or overlapping loads.
304
305 As mentioned in (1), the other CPUs in the system can be viewed as
306 committing sequences of stores to the memory system that the CPU being
307 considered can then perceive. A data dependency barrier issued by the CPU
308 under consideration guarantees that for any load preceding it, if that
309 load touches one of a sequence of stores from another CPU, then by the
310 time the barrier completes, the effects of all the stores prior to that
311 touched by the load will be perceptible to any loads issued after the data
312 dependency barrier.
313
314 See the "Examples of memory barrier sequences" subsection for diagrams
315 showing the ordering constraints.
316
317 [!] Note that the first load really has to have a _data_ dependency and
318 not a control dependency. If the address for the second load is dependent
319 on the first load, but the dependency is through a conditional rather than
320 actually loading the address itself, then it's a _control_ dependency and
321 a full read barrier or better is required. See the "Control dependencies"
322 subsection for more information.
323
324 [!] Note that data dependency barriers should normally be paired with
325 write barriers; see the "SMP barrier pairing" subsection.
326
327
328 (3) Read (or load) memory barriers.
329
330 A read barrier is a data dependency barrier plus a guarantee that all the
331 LOAD operations specified before the barrier will appear to happen before
332 all the LOAD operations specified after the barrier with respect to the
333 other components of the system.
334
335 A read barrier is a partial ordering on loads only; it is not required to
336 have any effect on stores.
337
338 Read memory barriers imply data dependency barriers, and so can substitute
339 for them.
340
341 [!] Note that read barriers should normally be paired with write barriers;
342 see the "SMP barrier pairing" subsection.
343
344
345 (4) General memory barriers.
346
347 A general memory barrier is a combination of both a read memory barrier
348 and a write memory barrier. It is a partial ordering over both loads and
349 stores.
350
351 General memory barriers imply both read and write memory barriers, and so
352 can substitute for either.
353
354
355And a couple of implicit varieties:
356
357 (5) LOCK operations.
358
359 This acts as a one-way permeable barrier. It guarantees that all memory
360 operations after the LOCK operation will appear to happen after the LOCK
361 operation with respect to the other components of the system.
362
363 Memory operations that occur before a LOCK operation may appear to happen
364 after it completes.
365
366 A LOCK operation should almost always be paired with an UNLOCK operation.
367
368
369 (6) UNLOCK operations.
370
371 This also acts as a one-way permeable barrier. It guarantees that all
372 memory operations before the UNLOCK operation will appear to happen before
373 the UNLOCK operation with respect to the other components of the system.
374
375 Memory operations that occur after an UNLOCK operation may appear to
376 happen before it completes.
377
378 LOCK and UNLOCK operations are guaranteed to appear with respect to each
379 other strictly in the order specified.
380
381 The use of LOCK and UNLOCK operations generally precludes the need for
382 other sorts of memory barrier (but note the exceptions mentioned in the
383 subsection "MMIO write barrier").
384
385
386Memory barriers are only required where there's a possibility of interaction
387between two CPUs or between a CPU and a device. If it can be guaranteed that
388there won't be any such interaction in any particular piece of code, then
389memory barriers are unnecessary in that piece of code.
390
391
392Note that these are the _minimum_ guarantees. Different architectures may give
393more substantial guarantees, but they may _not_ be relied upon outside of arch
394specific code.
395
396
397WHAT MAY NOT BE ASSUMED ABOUT MEMORY BARRIERS?
398----------------------------------------------
399
400There are certain things that the Linux kernel memory barriers do not guarantee:
401
402 (*) There is no guarantee that any of the memory accesses specified before a
403 memory barrier will be _complete_ by the completion of a memory barrier
404 instruction; the barrier can be considered to draw a line in that CPU's
405 access queue that accesses of the appropriate type may not cross.
406
407 (*) There is no guarantee that issuing a memory barrier on one CPU will have
408 any direct effect on another CPU or any other hardware in the system. The
409 indirect effect will be the order in which the second CPU sees the effects
410 of the first CPU's accesses occur, but see the next point:
411
412 (*) There is no guarantee that the a CPU will see the correct order of effects
413 from a second CPU's accesses, even _if_ the second CPU uses a memory
414 barrier, unless the first CPU _also_ uses a matching memory barrier (see
415 the subsection on "SMP Barrier Pairing").
416
417 (*) There is no guarantee that some intervening piece of off-the-CPU
418 hardware[*] will not reorder the memory accesses. CPU cache coherency
419 mechanisms should propagate the indirect effects of a memory barrier
420 between CPUs, but might not do so in order.
421
422 [*] For information on bus mastering DMA and coherency please read:
423
424 Documentation/pci.txt
425 Documentation/DMA-mapping.txt
426 Documentation/DMA-API.txt
427
428
429DATA DEPENDENCY BARRIERS
430------------------------
431
432The usage requirements of data dependency barriers are a little subtle, and
433it's not always obvious that they're needed. To illustrate, consider the
434following sequence of events:
435
436 CPU 1 CPU 2
437 =============== ===============
438 { A == 1, B == 2, C = 3, P == &A, Q == &C }
439 B = 4;
440 <write barrier>
441 P = &B
442 Q = P;
443 D = *Q;
444
445There's a clear data dependency here, and it would seem that by the end of the
446sequence, Q must be either &A or &B, and that:
447
448 (Q == &A) implies (D == 1)
449 (Q == &B) implies (D == 4)
450
451But! CPU 2's perception of P may be updated _before_ its perception of B, thus
452leading to the following situation:
453
454 (Q == &B) and (D == 2) ????
455
456Whilst this may seem like a failure of coherency or causality maintenance, it
457isn't, and this behaviour can be observed on certain real CPUs (such as the DEC
458Alpha).
459
460To deal with this, a data dependency barrier must be inserted between the
461address load and the data load:
462
463 CPU 1 CPU 2
464 =============== ===============
465 { A == 1, B == 2, C = 3, P == &A, Q == &C }
466 B = 4;
467 <write barrier>
468 P = &B
469 Q = P;
470 <data dependency barrier>
471 D = *Q;
472
473This enforces the occurrence of one of the two implications, and prevents the
474third possibility from arising.
475
476[!] Note that this extremely counterintuitive situation arises most easily on
477machines with split caches, so that, for example, one cache bank processes
478even-numbered cache lines and the other bank processes odd-numbered cache
479lines. The pointer P might be stored in an odd-numbered cache line, and the
480variable B might be stored in an even-numbered cache line. Then, if the
481even-numbered bank of the reading CPU's cache is extremely busy while the
482odd-numbered bank is idle, one can see the new value of the pointer P (&B),
483but the old value of the variable B (1).
484
485
486Another example of where data dependency barriers might by required is where a
487number is read from memory and then used to calculate the index for an array
488access:
489
490 CPU 1 CPU 2
491 =============== ===============
492 { M[0] == 1, M[1] == 2, M[3] = 3, P == 0, Q == 3 }
493 M[1] = 4;
494 <write barrier>
495 P = 1
496 Q = P;
497 <data dependency barrier>
498 D = M[Q];
499
500
501The data dependency barrier is very important to the RCU system, for example.
502See rcu_dereference() in include/linux/rcupdate.h. This permits the current
503target of an RCU'd pointer to be replaced with a new modified target, without
504the replacement target appearing to be incompletely initialised.
505
506See also the subsection on "Cache Coherency" for a more thorough example.
507
508
509CONTROL DEPENDENCIES
510--------------------
511
512A control dependency requires a full read memory barrier, not simply a data
513dependency barrier to make it work correctly. Consider the following bit of
514code:
515
516 q = &a;
517 if (p)
518 q = &b;
519 <data dependency barrier>
520 x = *q;
521
522This will not have the desired effect because there is no actual data
523dependency, but rather a control dependency that the CPU may short-circuit by
524attempting to predict the outcome in advance. In such a case what's actually
525required is:
526
527 q = &a;
528 if (p)
529 q = &b;
530 <read barrier>
531 x = *q;
532
533
534SMP BARRIER PAIRING
535-------------------
536
537When dealing with CPU-CPU interactions, certain types of memory barrier should
538always be paired. A lack of appropriate pairing is almost certainly an error.
539
540A write barrier should always be paired with a data dependency barrier or read
541barrier, though a general barrier would also be viable. Similarly a read
542barrier or a data dependency barrier should always be paired with at least an
543write barrier, though, again, a general barrier is viable:
544
545 CPU 1 CPU 2
546 =============== ===============
547 a = 1;
548 <write barrier>
549 b = 2; x = a;
550 <read barrier>
551 y = b;
552
553Or:
554
555 CPU 1 CPU 2
556 =============== ===============================
557 a = 1;
558 <write barrier>
559 b = &a; x = b;
560 <data dependency barrier>
561 y = *x;
562
563Basically, the read barrier always has to be there, even though it can be of
564the "weaker" type.
565
566
567EXAMPLES OF MEMORY BARRIER SEQUENCES
568------------------------------------
569
570Firstly, write barriers act as a partial orderings on store operations.
571Consider the following sequence of events:
572
573 CPU 1
574 =======================
575 STORE A = 1
576 STORE B = 2
577 STORE C = 3
578 <write barrier>
579 STORE D = 4
580 STORE E = 5
581
582This sequence of events is committed to the memory coherence system in an order
583that the rest of the system might perceive as the unordered set of { STORE A,
584STORE B, STORE C } all occuring before the unordered set of { STORE D, STORE E
585}:
586
587 +-------+ : :
588 | | +------+
589 | |------>| C=3 | } /\
590 | | : +------+ }----- \ -----> Events perceptible
591 | | : | A=1 | } \/ to rest of system
592 | | : +------+ }
593 | CPU 1 | : | B=2 | }
594 | | +------+ }
595 | | wwwwwwwwwwwwwwww } <--- At this point the write barrier
596 | | +------+ } requires all stores prior to the
597 | | : | E=5 | } barrier to be committed before
598 | | : +------+ } further stores may be take place.
599 | |------>| D=4 | }
600 | | +------+
601 +-------+ : :
602 |
603 | Sequence in which stores committed to memory system
604 | by CPU 1
605 V
606
607
608Secondly, data dependency barriers act as a partial orderings on data-dependent
609loads. Consider the following sequence of events:
610
611 CPU 1 CPU 2
612 ======================= =======================
613 { B = 7; X = 9; Y = 8; C = &Y }
614 STORE A = 1
615 STORE B = 2
616 <write barrier>
617 STORE C = &B LOAD X
618 STORE D = 4 LOAD C (gets &B)
619 LOAD *C (reads B)
620
621Without intervention, CPU 2 may perceive the events on CPU 1 in some
622effectively random order, despite the write barrier issued by CPU 1:
623
624 +-------+ : : : :
625 | | +------+ +-------+ | Sequence of update
626 | |------>| B=2 |----- --->| Y->8 | | of perception on
627 | | : +------+ \ +-------+ | CPU 2
628 | CPU 1 | : | A=1 | \ --->| C->&Y | V
629 | | +------+ | +-------+
630 | | wwwwwwwwwwwwwwww | : :
631 | | +------+ | : :
632 | | : | C=&B |--- | : : +-------+
633 | | : +------+ \ | +-------+ | |
634 | |------>| D=4 | ----------->| C->&B |------>| |
635 | | +------+ | +-------+ | |
636 +-------+ : : | : : | |
637 | : : | |
638 | : : | CPU 2 |
639 | +-------+ | |
640 Apparently incorrect ---> | | B->7 |------>| |
641 perception of B (!) | +-------+ | |
642 | : : | |
643 | +-------+ | |
644 The load of X holds ---> \ | X->9 |------>| |
645 up the maintenance \ +-------+ | |
646 of coherence of B ----->| B->2 | +-------+
647 +-------+
648 : :
649
650
651In the above example, CPU 2 perceives that B is 7, despite the load of *C
652(which would be B) coming after the the LOAD of C.
653
654If, however, a data dependency barrier were to be placed between the load of C
655and the load of *C (ie: B) on CPU 2:
656
657 CPU 1 CPU 2
658 ======================= =======================
659 { B = 7; X = 9; Y = 8; C = &Y }
660 STORE A = 1
661 STORE B = 2
662 <write barrier>
663 STORE C = &B LOAD X
664 STORE D = 4 LOAD C (gets &B)
665 <data dependency barrier>
666 LOAD *C (reads B)
667
668then the following will occur:
669
670 +-------+ : : : :
671 | | +------+ +-------+
672 | |------>| B=2 |----- --->| Y->8 |
673 | | : +------+ \ +-------+
674 | CPU 1 | : | A=1 | \ --->| C->&Y |
675 | | +------+ | +-------+
676 | | wwwwwwwwwwwwwwww | : :
677 | | +------+ | : :
678 | | : | C=&B |--- | : : +-------+
679 | | : +------+ \ | +-------+ | |
680 | |------>| D=4 | ----------->| C->&B |------>| |
681 | | +------+ | +-------+ | |
682 +-------+ : : | : : | |
683 | : : | |
684 | : : | CPU 2 |
685 | +-------+ | |
686 \ | X->9 |------>| |
687 \ +-------+ | |
688 ----->| B->2 | | |
689 +-------+ | |
690 Makes sure all effects ---> ddddddddddddddddd | |
691 prior to the store of C +-------+ | |
692 are perceptible to | B->2 |------>| |
693 successive loads +-------+ | |
694 : : +-------+
695
696
697And thirdly, a read barrier acts as a partial order on loads. Consider the
698following sequence of events:
699
700 CPU 1 CPU 2
701 ======================= =======================
702 STORE A=1
703 STORE B=2
704 STORE C=3
705 <write barrier>
706 STORE D=4
707 STORE E=5
708 LOAD A
709 LOAD B
710 LOAD C
711 LOAD D
712 LOAD E
713
714Without intervention, CPU 2 may then choose to perceive the events on CPU 1 in
715some effectively random order, despite the write barrier issued by CPU 1:
716
717 +-------+ : :
718 | | +------+
719 | |------>| C=3 | }
720 | | : +------+ }
721 | | : | A=1 | }
722 | | : +------+ }
723 | CPU 1 | : | B=2 | }---
724 | | +------+ } \
725 | | wwwwwwwwwwwww} \
726 | | +------+ } \ : : +-------+
727 | | : | E=5 | } \ +-------+ | |
728 | | : +------+ } \ { | C->3 |------>| |
729 | |------>| D=4 | } \ { +-------+ : | |
730 | | +------+ \ { | E->5 | : | |
731 +-------+ : : \ { +-------+ : | |
732 Transfer -->{ | A->1 | : | CPU 2 |
733 from CPU 1 { +-------+ : | |
734 to CPU 2 { | D->4 | : | |
735 { +-------+ : | |
736 { | B->2 |------>| |
737 +-------+ | |
738 : : +-------+
739
740
741If, however, a read barrier were to be placed between the load of C and the
742load of D on CPU 2, then the partial ordering imposed by CPU 1 will be
743perceived correctly by CPU 2.
744
745 +-------+ : :
746 | | +------+
747 | |------>| C=3 | }
748 | | : +------+ }
749 | | : | A=1 | }---
750 | | : +------+ } \
751 | CPU 1 | : | B=2 | } \
752 | | +------+ \
753 | | wwwwwwwwwwwwwwww \
754 | | +------+ \ : : +-------+
755 | | : | E=5 | } \ +-------+ | |
756 | | : +------+ }--- \ { | C->3 |------>| |
757 | |------>| D=4 | } \ \ { +-------+ : | |
758 | | +------+ \ -->{ | B->2 | : | |
759 +-------+ : : \ { +-------+ : | |
760 \ { | A->1 | : | CPU 2 |
761 \ +-------+ | |
762 At this point the read ----> \ rrrrrrrrrrrrrrrrr | |
763 barrier causes all effects \ +-------+ | |
764 prior to the storage of C \ { | E->5 | : | |
765 to be perceptible to CPU 2 -->{ +-------+ : | |
766 { | D->4 |------>| |
767 +-------+ | |
768 : : +-------+
769
770
771========================
772EXPLICIT KERNEL BARRIERS
773========================
774
775The Linux kernel has a variety of different barriers that act at different
776levels:
777
778 (*) Compiler barrier.
779
780 (*) CPU memory barriers.
781
782 (*) MMIO write barrier.
783
784
785COMPILER BARRIER
786----------------
787
788The Linux kernel has an explicit compiler barrier function that prevents the
789compiler from moving the memory accesses either side of it to the other side:
790
791 barrier();
792
793This a general barrier - lesser varieties of compiler barrier do not exist.
794
795The compiler barrier has no direct effect on the CPU, which may then reorder
796things however it wishes.
797
798
799CPU MEMORY BARRIERS
800-------------------
801
802The Linux kernel has eight basic CPU memory barriers:
803
804 TYPE MANDATORY SMP CONDITIONAL
805 =============== ======================= ===========================
806 GENERAL mb() smp_mb()
807 WRITE wmb() smp_wmb()
808 READ rmb() smp_rmb()
809 DATA DEPENDENCY read_barrier_depends() smp_read_barrier_depends()
810
811
812All CPU memory barriers unconditionally imply compiler barriers.
813
814SMP memory barriers are reduced to compiler barriers on uniprocessor compiled
815systems because it is assumed that a CPU will be appear to be self-consistent,
816and will order overlapping accesses correctly with respect to itself.
817
818[!] Note that SMP memory barriers _must_ be used to control the ordering of
819references to shared memory on SMP systems, though the use of locking instead
820is sufficient.
821
822Mandatory barriers should not be used to control SMP effects, since mandatory
823barriers unnecessarily impose overhead on UP systems. They may, however, be
824used to control MMIO effects on accesses through relaxed memory I/O windows.
825These are required even on non-SMP systems as they affect the order in which
826memory operations appear to a device by prohibiting both the compiler and the
827CPU from reordering them.
828
829
830There are some more advanced barrier functions:
831
832 (*) set_mb(var, value)
833 (*) set_wmb(var, value)
834
835 These assign the value to the variable and then insert at least a write
836 barrier after it, depending on the function. They aren't guaranteed to
837 insert anything more than a compiler barrier in a UP compilation.
838
839
840 (*) smp_mb__before_atomic_dec();
841 (*) smp_mb__after_atomic_dec();
842 (*) smp_mb__before_atomic_inc();
843 (*) smp_mb__after_atomic_inc();
844
845 These are for use with atomic add, subtract, increment and decrement
846 functions that don't return a value, especially when used for reference
847 counting. These functions do not imply memory barriers.
848
849 As an example, consider a piece of code that marks an object as being dead
850 and then decrements the object's reference count:
851
852 obj->dead = 1;
853 smp_mb__before_atomic_dec();
854 atomic_dec(&obj->ref_count);
855
856 This makes sure that the death mark on the object is perceived to be set
857 *before* the reference counter is decremented.
858
859 See Documentation/atomic_ops.txt for more information. See the "Atomic
860 operations" subsection for information on where to use these.
861
862
863 (*) smp_mb__before_clear_bit(void);
864 (*) smp_mb__after_clear_bit(void);
865
866 These are for use similar to the atomic inc/dec barriers. These are
867 typically used for bitwise unlocking operations, so care must be taken as
868 there are no implicit memory barriers here either.
869
870 Consider implementing an unlock operation of some nature by clearing a
871 locking bit. The clear_bit() would then need to be barriered like this:
872
873 smp_mb__before_clear_bit();
874 clear_bit( ... );
875
876 This prevents memory operations before the clear leaking to after it. See
877 the subsection on "Locking Functions" with reference to UNLOCK operation
878 implications.
879
880 See Documentation/atomic_ops.txt for more information. See the "Atomic
881 operations" subsection for information on where to use these.
882
883
884MMIO WRITE BARRIER
885------------------
886
887The Linux kernel also has a special barrier for use with memory-mapped I/O
888writes:
889
890 mmiowb();
891
892This is a variation on the mandatory write barrier that causes writes to weakly
893ordered I/O regions to be partially ordered. Its effects may go beyond the
894CPU->Hardware interface and actually affect the hardware at some level.
895
896See the subsection "Locks vs I/O accesses" for more information.
897
898
899===============================
900IMPLICIT KERNEL MEMORY BARRIERS
901===============================
902
903Some of the other functions in the linux kernel imply memory barriers, amongst
904which are locking, scheduling and memory allocation functions.
905
906This specification is a _minimum_ guarantee; any particular architecture may
907provide more substantial guarantees, but these may not be relied upon outside
908of arch specific code.
909
910
911LOCKING FUNCTIONS
912-----------------
913
914The Linux kernel has a number of locking constructs:
915
916 (*) spin locks
917 (*) R/W spin locks
918 (*) mutexes
919 (*) semaphores
920 (*) R/W semaphores
921 (*) RCU
922
923In all cases there are variants on "LOCK" operations and "UNLOCK" operations
924for each construct. These operations all imply certain barriers:
925
926 (1) LOCK operation implication:
927
928 Memory operations issued after the LOCK will be completed after the LOCK
929 operation has completed.
930
931 Memory operations issued before the LOCK may be completed after the LOCK
932 operation has completed.
933
934 (2) UNLOCK operation implication:
935
936 Memory operations issued before the UNLOCK will be completed before the
937 UNLOCK operation has completed.
938
939 Memory operations issued after the UNLOCK may be completed before the
940 UNLOCK operation has completed.
941
942 (3) LOCK vs LOCK implication:
943
944 All LOCK operations issued before another LOCK operation will be completed
945 before that LOCK operation.
946
947 (4) LOCK vs UNLOCK implication:
948
949 All LOCK operations issued before an UNLOCK operation will be completed
950 before the UNLOCK operation.
951
952 All UNLOCK operations issued before a LOCK operation will be completed
953 before the LOCK operation.
954
955 (5) Failed conditional LOCK implication:
956
957 Certain variants of the LOCK operation may fail, either due to being
958 unable to get the lock immediately, or due to receiving an unblocked
959 signal whilst asleep waiting for the lock to become available. Failed
960 locks do not imply any sort of barrier.
961
962Therefore, from (1), (2) and (4) an UNLOCK followed by an unconditional LOCK is
963equivalent to a full barrier, but a LOCK followed by an UNLOCK is not.
964
965[!] Note: one of the consequence of LOCKs and UNLOCKs being only one-way
966 barriers is that the effects instructions outside of a critical section may
967 seep into the inside of the critical section.
968
969Locks and semaphores may not provide any guarantee of ordering on UP compiled
970systems, and so cannot be counted on in such a situation to actually achieve
971anything at all - especially with respect to I/O accesses - unless combined
972with interrupt disabling operations.
973
974See also the section on "Inter-CPU locking barrier effects".
975
976
977As an example, consider the following:
978
979 *A = a;
980 *B = b;
981 LOCK
982 *C = c;
983 *D = d;
984 UNLOCK
985 *E = e;
986 *F = f;
987
988The following sequence of events is acceptable:
989
990 LOCK, {*F,*A}, *E, {*C,*D}, *B, UNLOCK
991
992 [+] Note that {*F,*A} indicates a combined access.
993
994But none of the following are:
995
996 {*F,*A}, *B, LOCK, *C, *D, UNLOCK, *E
997 *A, *B, *C, LOCK, *D, UNLOCK, *E, *F
998 *A, *B, LOCK, *C, UNLOCK, *D, *E, *F
999 *B, LOCK, *C, *D, UNLOCK, {*F,*A}, *E
1000
1001
1002
1003INTERRUPT DISABLING FUNCTIONS
1004-----------------------------
1005
1006Functions that disable interrupts (LOCK equivalent) and enable interrupts
1007(UNLOCK equivalent) will act as compiler barriers only. So if memory or I/O
1008barriers are required in such a situation, they must be provided from some
1009other means.
1010
1011
1012MISCELLANEOUS FUNCTIONS
1013-----------------------
1014
1015Other functions that imply barriers:
1016
1017 (*) schedule() and similar imply full memory barriers.
1018
1019 (*) Memory allocation and release functions imply full memory barriers.
1020
1021
1022=================================
1023INTER-CPU LOCKING BARRIER EFFECTS
1024=================================
1025
1026On SMP systems locking primitives give a more substantial form of barrier: one
1027that does affect memory access ordering on other CPUs, within the context of
1028conflict on any particular lock.
1029
1030
1031LOCKS VS MEMORY ACCESSES
1032------------------------
1033
1034Consider the following: the system has a pair of spinlocks (N) and (Q), and
1035three CPUs; then should the following sequence of events occur:
1036
1037 CPU 1 CPU 2
1038 =============================== ===============================
1039 *A = a; *E = e;
1040 LOCK M LOCK Q
1041 *B = b; *F = f;
1042 *C = c; *G = g;
1043 UNLOCK M UNLOCK Q
1044 *D = d; *H = h;
1045
1046Then there is no guarantee as to what order CPU #3 will see the accesses to *A
1047through *H occur in, other than the constraints imposed by the separate locks
1048on the separate CPUs. It might, for example, see:
1049
1050 *E, LOCK M, LOCK Q, *G, *C, *F, *A, *B, UNLOCK Q, *D, *H, UNLOCK M
1051
1052But it won't see any of:
1053
1054 *B, *C or *D preceding LOCK M
1055 *A, *B or *C following UNLOCK M
1056 *F, *G or *H preceding LOCK Q
1057 *E, *F or *G following UNLOCK Q
1058
1059
1060However, if the following occurs:
1061
1062 CPU 1 CPU 2
1063 =============================== ===============================
1064 *A = a;
1065 LOCK M [1]
1066 *B = b;
1067 *C = c;
1068 UNLOCK M [1]
1069 *D = d; *E = e;
1070 LOCK M [2]
1071 *F = f;
1072 *G = g;
1073 UNLOCK M [2]
1074 *H = h;
1075
1076CPU #3 might see:
1077
1078 *E, LOCK M [1], *C, *B, *A, UNLOCK M [1],
1079 LOCK M [2], *H, *F, *G, UNLOCK M [2], *D
1080
1081But assuming CPU #1 gets the lock first, it won't see any of:
1082
1083 *B, *C, *D, *F, *G or *H preceding LOCK M [1]
1084 *A, *B or *C following UNLOCK M [1]
1085 *F, *G or *H preceding LOCK M [2]
1086 *A, *B, *C, *E, *F or *G following UNLOCK M [2]
1087
1088
1089LOCKS VS I/O ACCESSES
1090---------------------
1091
1092Under certain circumstances (especially involving NUMA), I/O accesses within
1093two spinlocked sections on two different CPUs may be seen as interleaved by the
1094PCI bridge, because the PCI bridge does not necessarily participate in the
1095cache-coherence protocol, and is therefore incapable of issuing the required
1096read memory barriers.
1097
1098For example:
1099
1100 CPU 1 CPU 2
1101 =============================== ===============================
1102 spin_lock(Q)
1103 writel(0, ADDR)
1104 writel(1, DATA);
1105 spin_unlock(Q);
1106 spin_lock(Q);
1107 writel(4, ADDR);
1108 writel(5, DATA);
1109 spin_unlock(Q);
1110
1111may be seen by the PCI bridge as follows:
1112
1113 STORE *ADDR = 0, STORE *ADDR = 4, STORE *DATA = 1, STORE *DATA = 5
1114
1115which would probably cause the hardware to malfunction.
1116
1117
1118What is necessary here is to intervene with an mmiowb() before dropping the
1119spinlock, for example:
1120
1121 CPU 1 CPU 2
1122 =============================== ===============================
1123 spin_lock(Q)
1124 writel(0, ADDR)
1125 writel(1, DATA);
1126 mmiowb();
1127 spin_unlock(Q);
1128 spin_lock(Q);
1129 writel(4, ADDR);
1130 writel(5, DATA);
1131 mmiowb();
1132 spin_unlock(Q);
1133
1134this will ensure that the two stores issued on CPU #1 appear at the PCI bridge
1135before either of the stores issued on CPU #2.
1136
1137
1138Furthermore, following a store by a load to the same device obviates the need
1139for an mmiowb(), because the load forces the store to complete before the load
1140is performed:
1141
1142 CPU 1 CPU 2
1143 =============================== ===============================
1144 spin_lock(Q)
1145 writel(0, ADDR)
1146 a = readl(DATA);
1147 spin_unlock(Q);
1148 spin_lock(Q);
1149 writel(4, ADDR);
1150 b = readl(DATA);
1151 spin_unlock(Q);
1152
1153
1154See Documentation/DocBook/deviceiobook.tmpl for more information.
1155
1156
1157=================================
1158WHERE ARE MEMORY BARRIERS NEEDED?
1159=================================
1160
1161Under normal operation, memory operation reordering is generally not going to
1162be a problem as a single-threaded linear piece of code will still appear to
1163work correctly, even if it's in an SMP kernel. There are, however, three
1164circumstances in which reordering definitely _could_ be a problem:
1165
1166 (*) Interprocessor interaction.
1167
1168 (*) Atomic operations.
1169
1170 (*) Accessing devices (I/O).
1171
1172 (*) Interrupts.
1173
1174
1175INTERPROCESSOR INTERACTION
1176--------------------------
1177
1178When there's a system with more than one processor, more than one CPU in the
1179system may be working on the same data set at the same time. This can cause
1180synchronisation problems, and the usual way of dealing with them is to use
1181locks. Locks, however, are quite expensive, and so it may be preferable to
1182operate without the use of a lock if at all possible. In such a case
1183operations that affect both CPUs may have to be carefully ordered to prevent
1184a malfunction.
1185
1186Consider, for example, the R/W semaphore slow path. Here a waiting process is
1187queued on the semaphore, by virtue of it having a piece of its stack linked to
1188the semaphore's list of waiting processes:
1189
1190 struct rw_semaphore {
1191 ...
1192 spinlock_t lock;
1193 struct list_head waiters;
1194 };
1195
1196 struct rwsem_waiter {
1197 struct list_head list;
1198 struct task_struct *task;
1199 };
1200
1201To wake up a particular waiter, the up_read() or up_write() functions have to:
1202
1203 (1) read the next pointer from this waiter's record to know as to where the
1204 next waiter record is;
1205
1206 (4) read the pointer to the waiter's task structure;
1207
1208 (3) clear the task pointer to tell the waiter it has been given the semaphore;
1209
1210 (4) call wake_up_process() on the task; and
1211
1212 (5) release the reference held on the waiter's task struct.
1213
1214In otherwords, it has to perform this sequence of events:
1215
1216 LOAD waiter->list.next;
1217 LOAD waiter->task;
1218 STORE waiter->task;
1219 CALL wakeup
1220 RELEASE task
1221
1222and if any of these steps occur out of order, then the whole thing may
1223malfunction.
1224
1225Once it has queued itself and dropped the semaphore lock, the waiter does not
1226get the lock again; it instead just waits for its task pointer to be cleared
1227before proceeding. Since the record is on the waiter's stack, this means that
1228if the task pointer is cleared _before_ the next pointer in the list is read,
1229another CPU might start processing the waiter and might clobber the waiter's
1230stack before the up*() function has a chance to read the next pointer.
1231
1232Consider then what might happen to the above sequence of events:
1233
1234 CPU 1 CPU 2
1235 =============================== ===============================
1236 down_xxx()
1237 Queue waiter
1238 Sleep
1239 up_yyy()
1240 LOAD waiter->task;
1241 STORE waiter->task;
1242 Woken up by other event
1243 <preempt>
1244 Resume processing
1245 down_xxx() returns
1246 call foo()
1247 foo() clobbers *waiter
1248 </preempt>
1249 LOAD waiter->list.next;
1250 --- OOPS ---
1251
1252This could be dealt with using the semaphore lock, but then the down_xxx()
1253function has to needlessly get the spinlock again after being woken up.
1254
1255The way to deal with this is to insert a general SMP memory barrier:
1256
1257 LOAD waiter->list.next;
1258 LOAD waiter->task;
1259 smp_mb();
1260 STORE waiter->task;
1261 CALL wakeup
1262 RELEASE task
1263
1264In this case, the barrier makes a guarantee that all memory accesses before the
1265barrier will appear to happen before all the memory accesses after the barrier
1266with respect to the other CPUs on the system. It does _not_ guarantee that all
1267the memory accesses before the barrier will be complete by the time the barrier
1268instruction itself is complete.
1269
1270On a UP system - where this wouldn't be a problem - the smp_mb() is just a
1271compiler barrier, thus making sure the compiler emits the instructions in the
1272right order without actually intervening in the CPU. Since there there's only
1273one CPU, that CPU's dependency ordering logic will take care of everything
1274else.
1275
1276
1277ATOMIC OPERATIONS
1278-----------------
1279
1280Whilst they are technically interprocessor interaction considerations, atomic
1281operations are noted specially as some of them imply full memory barriers and
1282some don't, but they're very heavily relied on as a group throughout the
1283kernel.
1284
1285Any atomic operation that modifies some state in memory and returns information
1286about the state (old or new) implies an SMP-conditional general memory barrier
1287(smp_mb()) on each side of the actual operation. These include:
1288
1289 xchg();
1290 cmpxchg();
1291 atomic_cmpxchg();
1292 atomic_inc_return();
1293 atomic_dec_return();
1294 atomic_add_return();
1295 atomic_sub_return();
1296 atomic_inc_and_test();
1297 atomic_dec_and_test();
1298 atomic_sub_and_test();
1299 atomic_add_negative();
1300 atomic_add_unless();
1301 test_and_set_bit();
1302 test_and_clear_bit();
1303 test_and_change_bit();
1304
1305These are used for such things as implementing LOCK-class and UNLOCK-class
1306operations and adjusting reference counters towards object destruction, and as
1307such the implicit memory barrier effects are necessary.
1308
1309
1310The following operation are potential problems as they do _not_ imply memory
1311barriers, but might be used for implementing such things as UNLOCK-class
1312operations:
1313
1314 atomic_set();
1315 set_bit();
1316 clear_bit();
1317 change_bit();
1318
1319With these the appropriate explicit memory barrier should be used if necessary
1320(smp_mb__before_clear_bit() for instance).
1321
1322
1323The following also do _not_ imply memory barriers, and so may require explicit
1324memory barriers under some circumstances (smp_mb__before_atomic_dec() for
1325instance)):
1326
1327 atomic_add();
1328 atomic_sub();
1329 atomic_inc();
1330 atomic_dec();
1331
1332If they're used for statistics generation, then they probably don't need memory
1333barriers, unless there's a coupling between statistical data.
1334
1335If they're used for reference counting on an object to control its lifetime,
1336they probably don't need memory barriers because either the reference count
1337will be adjusted inside a locked section, or the caller will already hold
1338sufficient references to make the lock, and thus a memory barrier unnecessary.
1339
1340If they're used for constructing a lock of some description, then they probably
1341do need memory barriers as a lock primitive generally has to do things in a
1342specific order.
1343
1344
1345Basically, each usage case has to be carefully considered as to whether memory
1346barriers are needed or not.
1347
1348[!] Note that special memory barrier primitives are available for these
1349situations because on some CPUs the atomic instructions used imply full memory
1350barriers, and so barrier instructions are superfluous in conjunction with them,
1351and in such cases the special barrier primitives will be no-ops.
1352
1353See Documentation/atomic_ops.txt for more information.
1354
1355
1356ACCESSING DEVICES
1357-----------------
1358
1359Many devices can be memory mapped, and so appear to the CPU as if they're just
1360a set of memory locations. To control such a device, the driver usually has to
1361make the right memory accesses in exactly the right order.
1362
1363However, having a clever CPU or a clever compiler creates a potential problem
1364in that the carefully sequenced accesses in the driver code won't reach the
1365device in the requisite order if the CPU or the compiler thinks it is more
1366efficient to reorder, combine or merge accesses - something that would cause
1367the device to malfunction.
1368
1369Inside of the Linux kernel, I/O should be done through the appropriate accessor
1370routines - such as inb() or writel() - which know how to make such accesses
1371appropriately sequential. Whilst this, for the most part, renders the explicit
1372use of memory barriers unnecessary, there are a couple of situations where they
1373might be needed:
1374
1375 (1) On some systems, I/O stores are not strongly ordered across all CPUs, and
1376 so for _all_ general drivers locks should be used and mmiowb() must be
1377 issued prior to unlocking the critical section.
1378
1379 (2) If the accessor functions are used to refer to an I/O memory window with
1380 relaxed memory access properties, then _mandatory_ memory barriers are
1381 required to enforce ordering.
1382
1383See Documentation/DocBook/deviceiobook.tmpl for more information.
1384
1385
1386INTERRUPTS
1387----------
1388
1389A driver may be interrupted by its own interrupt service routine, and thus the
1390two parts of the driver may interfere with each other's attempts to control or
1391access the device.
1392
1393This may be alleviated - at least in part - by disabling local interrupts (a
1394form of locking), such that the critical operations are all contained within
1395the interrupt-disabled section in the driver. Whilst the driver's interrupt
1396routine is executing, the driver's core may not run on the same CPU, and its
1397interrupt is not permitted to happen again until the current interrupt has been
1398handled, thus the interrupt handler does not need to lock against that.
1399
1400However, consider a driver that was talking to an ethernet card that sports an
1401address register and a data register. If that driver's core talks to the card
1402under interrupt-disablement and then the driver's interrupt handler is invoked:
1403
1404 LOCAL IRQ DISABLE
1405 writew(ADDR, 3);
1406 writew(DATA, y);
1407 LOCAL IRQ ENABLE
1408 <interrupt>
1409 writew(ADDR, 4);
1410 q = readw(DATA);
1411 </interrupt>
1412
1413The store to the data register might happen after the second store to the
1414address register if ordering rules are sufficiently relaxed:
1415
1416 STORE *ADDR = 3, STORE *ADDR = 4, STORE *DATA = y, q = LOAD *DATA
1417
1418
1419If ordering rules are relaxed, it must be assumed that accesses done inside an
1420interrupt disabled section may leak outside of it and may interleave with
1421accesses performed in an interrupt - and vice versa - unless implicit or
1422explicit barriers are used.
1423
1424Normally this won't be a problem because the I/O accesses done inside such
1425sections will include synchronous load operations on strictly ordered I/O
1426registers that form implicit I/O barriers. If this isn't sufficient then an
1427mmiowb() may need to be used explicitly.
1428
1429
1430A similar situation may occur between an interrupt routine and two routines
1431running on separate CPUs that communicate with each other. If such a case is
1432likely, then interrupt-disabling locks should be used to guarantee ordering.
1433
1434
1435==========================
1436KERNEL I/O BARRIER EFFECTS
1437==========================
1438
1439When accessing I/O memory, drivers should use the appropriate accessor
1440functions:
1441
1442 (*) inX(), outX():
1443
1444 These are intended to talk to I/O space rather than memory space, but
1445 that's primarily a CPU-specific concept. The i386 and x86_64 processors do
1446 indeed have special I/O space access cycles and instructions, but many
1447 CPUs don't have such a concept.
1448
1449 The PCI bus, amongst others, defines an I/O space concept - which on such
1450 CPUs as i386 and x86_64 cpus readily maps to the CPU's concept of I/O
1451 space. However, it may also mapped as a virtual I/O space in the CPU's
1452 memory map, particularly on those CPUs that don't support alternate
1453 I/O spaces.
1454
1455 Accesses to this space may be fully synchronous (as on i386), but
1456 intermediary bridges (such as the PCI host bridge) may not fully honour
1457 that.
1458
1459 They are guaranteed to be fully ordered with respect to each other.
1460
1461 They are not guaranteed to be fully ordered with respect to other types of
1462 memory and I/O operation.
1463
1464 (*) readX(), writeX():
1465
1466 Whether these are guaranteed to be fully ordered and uncombined with
1467 respect to each other on the issuing CPU depends on the characteristics
1468 defined for the memory window through which they're accessing. On later
1469 i386 architecture machines, for example, this is controlled by way of the
1470 MTRR registers.
1471
1472 Ordinarily, these will be guaranteed to be fully ordered and uncombined,,
1473 provided they're not accessing a prefetchable device.
1474
1475 However, intermediary hardware (such as a PCI bridge) may indulge in
1476 deferral if it so wishes; to flush a store, a load from the same location
1477 is preferred[*], but a load from the same device or from configuration
1478 space should suffice for PCI.
1479
1480 [*] NOTE! attempting to load from the same location as was written to may
1481 cause a malfunction - consider the 16550 Rx/Tx serial registers for
1482 example.
1483
1484 Used with prefetchable I/O memory, an mmiowb() barrier may be required to
1485 force stores to be ordered.
1486
1487 Please refer to the PCI specification for more information on interactions
1488 between PCI transactions.
1489
1490 (*) readX_relaxed()
1491
1492 These are similar to readX(), but are not guaranteed to be ordered in any
1493 way. Be aware that there is no I/O read barrier available.
1494
1495 (*) ioreadX(), iowriteX()
1496
1497 These will perform as appropriate for the type of access they're actually
1498 doing, be it inX()/outX() or readX()/writeX().
1499
1500
1501========================================
1502ASSUMED MINIMUM EXECUTION ORDERING MODEL
1503========================================
1504
1505It has to be assumed that the conceptual CPU is weakly-ordered but that it will
1506maintain the appearance of program causality with respect to itself. Some CPUs
1507(such as i386 or x86_64) are more constrained than others (such as powerpc or
1508frv), and so the most relaxed case (namely DEC Alpha) must be assumed outside
1509of arch-specific code.
1510
1511This means that it must be considered that the CPU will execute its instruction
1512stream in any order it feels like - or even in parallel - provided that if an
1513instruction in the stream depends on the an earlier instruction, then that
1514earlier instruction must be sufficiently complete[*] before the later
1515instruction may proceed; in other words: provided that the appearance of
1516causality is maintained.
1517
1518 [*] Some instructions have more than one effect - such as changing the
1519 condition codes, changing registers or changing memory - and different
1520 instructions may depend on different effects.
1521
1522A CPU may also discard any instruction sequence that winds up having no
1523ultimate effect. For example, if two adjacent instructions both load an
1524immediate value into the same register, the first may be discarded.
1525
1526
1527Similarly, it has to be assumed that compiler might reorder the instruction
1528stream in any way it sees fit, again provided the appearance of causality is
1529maintained.
1530
1531
1532============================
1533THE EFFECTS OF THE CPU CACHE
1534============================
1535
1536The way cached memory operations are perceived across the system is affected to
1537a certain extent by the caches that lie between CPUs and memory, and by the
1538memory coherence system that maintains the consistency of state in the system.
1539
1540As far as the way a CPU interacts with another part of the system through the
1541caches goes, the memory system has to include the CPU's caches, and memory
1542barriers for the most part act at the interface between the CPU and its cache
1543(memory barriers logically act on the dotted line in the following diagram):
1544
1545 <--- CPU ---> : <----------- Memory ----------->
1546 :
1547 +--------+ +--------+ : +--------+ +-----------+
1548 | | | | : | | | | +--------+
1549 | CPU | | Memory | : | CPU | | | | |
1550 | Core |--->| Access |----->| Cache |<-->| | | |
1551 | | | Queue | : | | | |--->| Memory |
1552 | | | | : | | | | | |
1553 +--------+ +--------+ : +--------+ | | | |
1554 : | Cache | +--------+
1555 : | Coherency |
1556 : | Mechanism | +--------+
1557 +--------+ +--------+ : +--------+ | | | |
1558 | | | | : | | | | | |
1559 | CPU | | Memory | : | CPU | | |--->| Device |
1560 | Core |--->| Access |----->| Cache |<-->| | | |
1561 | | | Queue | : | | | | | |
1562 | | | | : | | | | +--------+
1563 +--------+ +--------+ : +--------+ +-----------+
1564 :
1565 :
1566
1567Although any particular load or store may not actually appear outside of the
1568CPU that issued it since it may have been satisfied within the CPU's own cache,
1569it will still appear as if the full memory access had taken place as far as the
1570other CPUs are concerned since the cache coherency mechanisms will migrate the
1571cacheline over to the accessing CPU and propagate the effects upon conflict.
1572
1573The CPU core may execute instructions in any order it deems fit, provided the
1574expected program causality appears to be maintained. Some of the instructions
1575generate load and store operations which then go into the queue of memory
1576accesses to be performed. The core may place these in the queue in any order
1577it wishes, and continue execution until it is forced to wait for an instruction
1578to complete.
1579
1580What memory barriers are concerned with is controlling the order in which
1581accesses cross from the CPU side of things to the memory side of things, and
1582the order in which the effects are perceived to happen by the other observers
1583in the system.
1584
1585[!] Memory barriers are _not_ needed within a given CPU, as CPUs always see
1586their own loads and stores as if they had happened in program order.
1587
1588[!] MMIO or other device accesses may bypass the cache system. This depends on
1589the properties of the memory window through which devices are accessed and/or
1590the use of any special device communication instructions the CPU may have.
1591
1592
1593CACHE COHERENCY
1594---------------
1595
1596Life isn't quite as simple as it may appear above, however: for while the
1597caches are expected to be coherent, there's no guarantee that that coherency
1598will be ordered. This means that whilst changes made on one CPU will
1599eventually become visible on all CPUs, there's no guarantee that they will
1600become apparent in the same order on those other CPUs.
1601
1602
1603Consider dealing with a system that has pair of CPUs (1 & 2), each of which has
1604a pair of parallel data caches (CPU 1 has A/B, and CPU 2 has C/D):
1605
1606 :
1607 : +--------+
1608 : +---------+ | |
1609 +--------+ : +--->| Cache A |<------->| |
1610 | | : | +---------+ | |
1611 | CPU 1 |<---+ | |
1612 | | : | +---------+ | |
1613 +--------+ : +--->| Cache B |<------->| |
1614 : +---------+ | |
1615 : | Memory |
1616 : +---------+ | System |
1617 +--------+ : +--->| Cache C |<------->| |
1618 | | : | +---------+ | |
1619 | CPU 2 |<---+ | |
1620 | | : | +---------+ | |
1621 +--------+ : +--->| Cache D |<------->| |
1622 : +---------+ | |
1623 : +--------+
1624 :
1625
1626Imagine the system has the following properties:
1627
1628 (*) an odd-numbered cache line may be in cache A, cache C or it may still be
1629 resident in memory;
1630
1631 (*) an even-numbered cache line may be in cache B, cache D or it may still be
1632 resident in memory;
1633
1634 (*) whilst the CPU core is interrogating one cache, the other cache may be
1635 making use of the bus to access the rest of the system - perhaps to
1636 displace a dirty cacheline or to do a speculative load;
1637
1638 (*) each cache has a queue of operations that need to be applied to that cache
1639 to maintain coherency with the rest of the system;
1640
1641 (*) the coherency queue is not flushed by normal loads to lines already
1642 present in the cache, even though the contents of the queue may
1643 potentially effect those loads.
1644
1645Imagine, then, that two writes are made on the first CPU, with a write barrier
1646between them to guarantee that they will appear to reach that CPU's caches in
1647the requisite order:
1648
1649 CPU 1 CPU 2 COMMENT
1650 =============== =============== =======================================
1651 u == 0, v == 1 and p == &u, q == &u
1652 v = 2;
1653 smp_wmb(); Make sure change to v visible before
1654 change to p
1655 <A:modify v=2> v is now in cache A exclusively
1656 p = &v;
1657 <B:modify p=&v> p is now in cache B exclusively
1658
1659The write memory barrier forces the other CPUs in the system to perceive that
1660the local CPU's caches have apparently been updated in the correct order. But
1661now imagine that the second CPU that wants to read those values:
1662
1663 CPU 1 CPU 2 COMMENT
1664 =============== =============== =======================================
1665 ...
1666 q = p;
1667 x = *q;
1668
1669The above pair of reads may then fail to happen in expected order, as the
1670cacheline holding p may get updated in one of the second CPU's caches whilst
1671the update to the cacheline holding v is delayed in the other of the second
1672CPU's caches by some other cache event:
1673
1674 CPU 1 CPU 2 COMMENT
1675 =============== =============== =======================================
1676 u == 0, v == 1 and p == &u, q == &u
1677 v = 2;
1678 smp_wmb();
1679 <A:modify v=2> <C:busy>
1680 <C:queue v=2>
1681 p = &b; q = p;
1682 <D:request p>
1683 <B:modify p=&v> <D:commit p=&v>
1684 <D:read p>
1685 x = *q;
1686 <C:read *q> Reads from v before v updated in cache
1687 <C:unbusy>
1688 <C:commit v=2>
1689
1690Basically, whilst both cachelines will be updated on CPU 2 eventually, there's
1691no guarantee that, without intervention, the order of update will be the same
1692as that committed on CPU 1.
1693
1694
1695To intervene, we need to interpolate a data dependency barrier or a read
1696barrier between the loads. This will force the cache to commit its coherency
1697queue before processing any further requests:
1698
1699 CPU 1 CPU 2 COMMENT
1700 =============== =============== =======================================
1701 u == 0, v == 1 and p == &u, q == &u
1702 v = 2;
1703 smp_wmb();
1704 <A:modify v=2> <C:busy>
1705 <C:queue v=2>
1706 p = &b; q = p;
1707 <D:request p>
1708 <B:modify p=&v> <D:commit p=&v>
1709 <D:read p>
1710 smp_read_barrier_depends()
1711 <C:unbusy>
1712 <C:commit v=2>
1713 x = *q;
1714 <C:read *q> Reads from v after v updated in cache
1715
1716
1717This sort of problem can be encountered on DEC Alpha processors as they have a
1718split cache that improves performance by making better use of the data bus.
1719Whilst most CPUs do imply a data dependency barrier on the read when a memory
1720access depends on a read, not all do, so it may not be relied on.
1721
1722Other CPUs may also have split caches, but must coordinate between the various
1723cachelets for normal memory accesss. The semantics of the Alpha removes the
1724need for coordination in absence of memory barriers.
1725
1726
1727CACHE COHERENCY VS DMA
1728----------------------
1729
1730Not all systems maintain cache coherency with respect to devices doing DMA. In
1731such cases, a device attempting DMA may obtain stale data from RAM because
1732dirty cache lines may be resident in the caches of various CPUs, and may not
1733have been written back to RAM yet. To deal with this, the appropriate part of
1734the kernel must flush the overlapping bits of cache on each CPU (and maybe
1735invalidate them as well).
1736
1737In addition, the data DMA'd to RAM by a device may be overwritten by dirty
1738cache lines being written back to RAM from a CPU's cache after the device has
1739installed its own data, or cache lines simply present in a CPUs cache may
1740simply obscure the fact that RAM has been updated, until at such time as the
1741cacheline is discarded from the CPU's cache and reloaded. To deal with this,
1742the appropriate part of the kernel must invalidate the overlapping bits of the
1743cache on each CPU.
1744
1745See Documentation/cachetlb.txt for more information on cache management.
1746
1747
1748CACHE COHERENCY VS MMIO
1749-----------------------
1750
1751Memory mapped I/O usually takes place through memory locations that are part of
1752a window in the CPU's memory space that have different properties assigned than
1753the usual RAM directed window.
1754
1755Amongst these properties is usually the fact that such accesses bypass the
1756caching entirely and go directly to the device buses. This means MMIO accesses
1757may, in effect, overtake accesses to cached memory that were emitted earlier.
1758A memory barrier isn't sufficient in such a case, but rather the cache must be
1759flushed between the cached memory write and the MMIO access if the two are in
1760any way dependent.
1761
1762
1763=========================
1764THE THINGS CPUS GET UP TO
1765=========================
1766
1767A programmer might take it for granted that the CPU will perform memory
1768operations in exactly the order specified, so that if a CPU is, for example,
1769given the following piece of code to execute:
1770
1771 a = *A;
1772 *B = b;
1773 c = *C;
1774 d = *D;
1775 *E = e;
1776
1777They would then expect that the CPU will complete the memory operation for each
1778instruction before moving on to the next one, leading to a definite sequence of
1779operations as seen by external observers in the system:
1780
1781 LOAD *A, STORE *B, LOAD *C, LOAD *D, STORE *E.
1782
1783
1784Reality is, of course, much messier. With many CPUs and compilers, the above
1785assumption doesn't hold because:
1786
1787 (*) loads are more likely to need to be completed immediately to permit
1788 execution progress, whereas stores can often be deferred without a
1789 problem;
1790
1791 (*) loads may be done speculatively, and the result discarded should it prove
1792 to have been unnecessary;
1793
1794 (*) loads may be done speculatively, leading to the result having being
1795 fetched at the wrong time in the expected sequence of events;
1796
1797 (*) the order of the memory accesses may be rearranged to promote better use
1798 of the CPU buses and caches;
1799
1800 (*) loads and stores may be combined to improve performance when talking to
1801 memory or I/O hardware that can do batched accesses of adjacent locations,
1802 thus cutting down on transaction setup costs (memory and PCI devices may
1803 both be able to do this); and
1804
1805 (*) the CPU's data cache may affect the ordering, and whilst cache-coherency
1806 mechanisms may alleviate this - once the store has actually hit the cache
1807 - there's no guarantee that the coherency management will be propagated in
1808 order to other CPUs.
1809
1810So what another CPU, say, might actually observe from the above piece of code
1811is:
1812
1813 LOAD *A, ..., LOAD {*C,*D}, STORE *E, STORE *B
1814
1815 (Where "LOAD {*C,*D}" is a combined load)
1816
1817
1818However, it is guaranteed that a CPU will be self-consistent: it will see its
1819_own_ accesses appear to be correctly ordered, without the need for a memory
1820barrier. For instance with the following code:
1821
1822 U = *A;
1823 *A = V;
1824 *A = W;
1825 X = *A;
1826 *A = Y;
1827 Z = *A;
1828
1829and assuming no intervention by an external influence, it can be assumed that
1830the final result will appear to be:
1831
1832 U == the original value of *A
1833 X == W
1834 Z == Y
1835 *A == Y
1836
1837The code above may cause the CPU to generate the full sequence of memory
1838accesses:
1839
1840 U=LOAD *A, STORE *A=V, STORE *A=W, X=LOAD *A, STORE *A=Y, Z=LOAD *A
1841
1842in that order, but, without intervention, the sequence may have almost any
1843combination of elements combined or discarded, provided the program's view of
1844the world remains consistent.
1845
1846The compiler may also combine, discard or defer elements of the sequence before
1847the CPU even sees them.
1848
1849For instance:
1850
1851 *A = V;
1852 *A = W;
1853
1854may be reduced to:
1855
1856 *A = W;
1857
1858since, without a write barrier, it can be assumed that the effect of the
1859storage of V to *A is lost. Similarly:
1860
1861 *A = Y;
1862 Z = *A;
1863
1864may, without a memory barrier, be reduced to:
1865
1866 *A = Y;
1867 Z = Y;
1868
1869and the LOAD operation never appear outside of the CPU.
1870
1871
1872AND THEN THERE'S THE ALPHA
1873--------------------------
1874
1875The DEC Alpha CPU is one of the most relaxed CPUs there is. Not only that,
1876some versions of the Alpha CPU have a split data cache, permitting them to have
1877two semantically related cache lines updating at separate times. This is where
1878the data dependency barrier really becomes necessary as this synchronises both
1879caches with the memory coherence system, thus making it seem like pointer
1880changes vs new data occur in the right order.
1881
1882The Alpha defines the Linux's kernel's memory barrier model.
1883
1884See the subsection on "Cache Coherency" above.
1885
1886
1887==========
1888REFERENCES
1889==========
1890
1891Alpha AXP Architecture Reference Manual, Second Edition (Sites & Witek,
1892Digital Press)
1893 Chapter 5.2: Physical Address Space Characteristics
1894 Chapter 5.4: Caches and Write Buffers
1895 Chapter 5.5: Data Sharing
1896 Chapter 5.6: Read/Write Ordering
1897
1898AMD64 Architecture Programmer's Manual Volume 2: System Programming
1899 Chapter 7.1: Memory-Access Ordering
1900 Chapter 7.4: Buffering and Combining Memory Writes
1901
1902IA-32 Intel Architecture Software Developer's Manual, Volume 3:
1903System Programming Guide
1904 Chapter 7.1: Locked Atomic Operations
1905 Chapter 7.2: Memory Ordering
1906 Chapter 7.4: Serializing Instructions
1907
1908The SPARC Architecture Manual, Version 9
1909 Chapter 8: Memory Models
1910 Appendix D: Formal Specification of the Memory Models
1911 Appendix J: Programming with the Memory Models
1912
1913UltraSPARC Programmer Reference Manual
1914 Chapter 5: Memory Accesses and Cacheability
1915 Chapter 15: Sparc-V9 Memory Models
1916
1917UltraSPARC III Cu User's Manual
1918 Chapter 9: Memory Models
1919
1920UltraSPARC IIIi Processor User's Manual
1921 Chapter 8: Memory Models
1922
1923UltraSPARC Architecture 2005
1924 Chapter 9: Memory
1925 Appendix D: Formal Specifications of the Memory Models
1926
1927UltraSPARC T1 Supplement to the UltraSPARC Architecture 2005
1928 Chapter 8: Memory Models
1929 Appendix F: Caches and Cache Coherency
1930
1931Solaris Internals, Core Kernel Architecture, p63-68:
1932 Chapter 3.3: Hardware Considerations for Locks and
1933 Synchronization
1934
1935Unix Systems for Modern Architectures, Symmetric Multiprocessing and Caching
1936for Kernel Programmers:
1937 Chapter 13: Other Memory Models
1938
1939Intel Itanium Architecture Software Developer's Manual: Volume 1:
1940 Section 2.6: Speculation
1941 Section 4.4: Memory Access
diff --git a/Documentation/mtrr.txt b/Documentation/mtrr.txt
index b78af1c32996..c39ac395970e 100644
--- a/Documentation/mtrr.txt
+++ b/Documentation/mtrr.txt
@@ -138,19 +138,29 @@ Reading MTRRs from a C program using ioctl()'s:
138 138
139*/ 139*/
140#include <stdio.h> 140#include <stdio.h>
141#include <stdlib.h>
141#include <string.h> 142#include <string.h>
142#include <sys/types.h> 143#include <sys/types.h>
143#include <sys/stat.h> 144#include <sys/stat.h>
144#include <fcntl.h> 145#include <fcntl.h>
145#include <sys/ioctl.h> 146#include <sys/ioctl.h>
146#include <errno.h> 147#include <errno.h>
147#define MTRR_NEED_STRINGS
148#include <asm/mtrr.h> 148#include <asm/mtrr.h>
149 149
150#define TRUE 1 150#define TRUE 1
151#define FALSE 0 151#define FALSE 0
152#define ERRSTRING strerror (errno) 152#define ERRSTRING strerror (errno)
153 153
154static char *mtrr_strings[MTRR_NUM_TYPES] =
155{
156 "uncachable", /* 0 */
157 "write-combining", /* 1 */
158 "?", /* 2 */
159 "?", /* 3 */
160 "write-through", /* 4 */
161 "write-protect", /* 5 */
162 "write-back", /* 6 */
163};
154 164
155int main () 165int main ()
156{ 166{
@@ -232,13 +242,22 @@ Creating MTRRs from a C programme using ioctl()'s:
232#include <fcntl.h> 242#include <fcntl.h>
233#include <sys/ioctl.h> 243#include <sys/ioctl.h>
234#include <errno.h> 244#include <errno.h>
235#define MTRR_NEED_STRINGS
236#include <asm/mtrr.h> 245#include <asm/mtrr.h>
237 246
238#define TRUE 1 247#define TRUE 1
239#define FALSE 0 248#define FALSE 0
240#define ERRSTRING strerror (errno) 249#define ERRSTRING strerror (errno)
241 250
251static char *mtrr_strings[MTRR_NUM_TYPES] =
252{
253 "uncachable", /* 0 */
254 "write-combining", /* 1 */
255 "?", /* 2 */
256 "?", /* 3 */
257 "write-through", /* 4 */
258 "write-protect", /* 5 */
259 "write-back", /* 6 */
260};
242 261
243int main (int argc, char **argv) 262int main (int argc, char **argv)
244{ 263{
diff --git a/Documentation/networking/TODO b/Documentation/networking/TODO
deleted file mode 100644
index 66d36ff14bae..000000000000
--- a/Documentation/networking/TODO
+++ /dev/null
@@ -1,18 +0,0 @@
1To-do items for network drivers
2-------------------------------
3
4* Move ethernet crc routine to generic code
5
6* (for 2.5) Integrate Jamal Hadi Salim's netdev Rx polling API change
7
8* Audit all net drivers to make sure magic packet / wake-on-lan /
9 similar features are disabled in the driver by default.
10
11* Audit all net drivers to make sure the module always prints out a
12 version string when loaded as a module, but only prints a version
13 string when built into the kernel if a device is detected.
14
15* Add ETHTOOL_GDRVINFO ioctl support to all ethernet drivers.
16
17* dmfe PCI DMA is totally wrong and only works on x86
18
diff --git a/Documentation/networking/bcm43xx.txt b/Documentation/networking/bcm43xx.txt
new file mode 100644
index 000000000000..28541d2bee1e
--- /dev/null
+++ b/Documentation/networking/bcm43xx.txt
@@ -0,0 +1,36 @@
1
2 BCM43xx Linux Driver Project
3 ============================
4
5About this software
6-------------------
7
8The goal of this project is to develop a linux driver for Broadcom
9BCM43xx chips, based on the specification at
10http://bcm-specs.sipsolutions.net/
11
12The project page is http://bcm43xx.berlios.de/
13
14
15Requirements
16------------
17
181) Linux Kernel 2.6.16 or later
19 http://www.kernel.org/
20
21 You may want to configure your kernel with:
22
23 CONFIG_DEBUG_FS (optional):
24 -> Kernel hacking
25 -> Debug Filesystem
26
272) SoftMAC IEEE 802.11 Networking Stack extension and patched ieee80211
28 modules:
29 http://softmac.sipsolutions.net/
30
313) Firmware Files
32
33 Please try fwcutter. Fwcutter can extract the firmware from various
34 binary driver files. It supports driver files from Windows, MacOS and
35 Linux. You can get fwcutter from http://bcm43xx.berlios.de/.
36 Also, fwcutter comes with a README file for further instructions.
diff --git a/Documentation/networking/packet_mmap.txt b/Documentation/networking/packet_mmap.txt
index 4fc8e9874320..aaf99d5f0dad 100644
--- a/Documentation/networking/packet_mmap.txt
+++ b/Documentation/networking/packet_mmap.txt
@@ -254,7 +254,7 @@ and, the number of frames be
254 254
255 <block number> * <block size> / <frame size> 255 <block number> * <block size> / <frame size>
256 256
257Suposse the following parameters, which apply for 2.6 kernel and an 257Suppose the following parameters, which apply for 2.6 kernel and an
258i386 architecture: 258i386 architecture:
259 259
260 <size-max> = 131072 bytes 260 <size-max> = 131072 bytes
diff --git a/Documentation/networking/tuntap.txt b/Documentation/networking/tuntap.txt
index ec3d109d787a..76750fb9151a 100644
--- a/Documentation/networking/tuntap.txt
+++ b/Documentation/networking/tuntap.txt
@@ -138,7 +138,7 @@ This means that you have to read/write IP packets when you are using tun and
138ethernet frames when using tap. 138ethernet frames when using tap.
139 139
1405. What is the difference between BPF and TUN/TAP driver? 1405. What is the difference between BPF and TUN/TAP driver?
141BFP is an advanced packet filter. It can be attached to existing 141BPF is an advanced packet filter. It can be attached to existing
142network interface. It does not provide a virtual network interface. 142network interface. It does not provide a virtual network interface.
143A TUN/TAP driver does provide a virtual network interface and it is possible 143A TUN/TAP driver does provide a virtual network interface and it is possible
144to attach BPF to this interface. 144to attach BPF to this interface.
diff --git a/Documentation/networking/xfrm_sync.txt b/Documentation/networking/xfrm_sync.txt
new file mode 100644
index 000000000000..8be626f7c0b8
--- /dev/null
+++ b/Documentation/networking/xfrm_sync.txt
@@ -0,0 +1,166 @@
1
2The sync patches work is based on initial patches from
3Krisztian <hidden@balabit.hu> and others and additional patches
4from Jamal <hadi@cyberus.ca>.
5
6The end goal for syncing is to be able to insert attributes + generate
7events so that the an SA can be safely moved from one machine to another
8for HA purposes.
9The idea is to synchronize the SA so that the takeover machine can do
10the processing of the SA as accurate as possible if it has access to it.
11
12We already have the ability to generate SA add/del/upd events.
13These patches add ability to sync and have accurate lifetime byte (to
14ensure proper decay of SAs) and replay counters to avoid replay attacks
15with as minimal loss at failover time.
16This way a backup stays as closely uptodate as an active member.
17
18Because the above items change for every packet the SA receives,
19it is possible for a lot of the events to be generated.
20For this reason, we also add a nagle-like algorithm to restrict
21the events. i.e we are going to set thresholds to say "let me
22know if the replay sequence threshold is reached or 10 secs have passed"
23These thresholds are set system-wide via sysctls or can be updated
24per SA.
25
26The identified items that need to be synchronized are:
27- the lifetime byte counter
28note that: lifetime time limit is not important if you assume the failover
29machine is known ahead of time since the decay of the time countdown
30is not driven by packet arrival.
31- the replay sequence for both inbound and outbound
32
331) Message Structure
34----------------------
35
36nlmsghdr:aevent_id:optional-TLVs.
37
38The netlink message types are:
39
40XFRM_MSG_NEWAE and XFRM_MSG_GETAE.
41
42A XFRM_MSG_GETAE does not have TLVs.
43A XFRM_MSG_NEWAE will have at least two TLVs (as is
44discussed further below).
45
46aevent_id structure looks like:
47
48 struct xfrm_aevent_id {
49 struct xfrm_usersa_id sa_id;
50 __u32 flags;
51 };
52
53xfrm_usersa_id in this message layout identifies the SA.
54
55flags are used to indicate different things. The possible
56flags are:
57 XFRM_AE_RTHR=1, /* replay threshold*/
58 XFRM_AE_RVAL=2, /* replay value */
59 XFRM_AE_LVAL=4, /* lifetime value */
60 XFRM_AE_ETHR=8, /* expiry timer threshold */
61 XFRM_AE_CR=16, /* Event cause is replay update */
62 XFRM_AE_CE=32, /* Event cause is timer expiry */
63 XFRM_AE_CU=64, /* Event cause is policy update */
64
65How these flags are used is dependent on the direction of the
66message (kernel<->user) as well the cause (config, query or event).
67This is described below in the different messages.
68
69The pid will be set appropriately in netlink to recognize direction
70(0 to the kernel and pid = processid that created the event
71when going from kernel to user space)
72
73A program needs to subscribe to multicast group XFRMNLGRP_AEVENTS
74to get notified of these events.
75
762) TLVS reflect the different parameters:
77-----------------------------------------
78
79a) byte value (XFRMA_LTIME_VAL)
80This TLV carries the running/current counter for byte lifetime since
81last event.
82
83b)replay value (XFRMA_REPLAY_VAL)
84This TLV carries the running/current counter for replay sequence since
85last event.
86
87c)replay threshold (XFRMA_REPLAY_THRESH)
88This TLV carries the threshold being used by the kernel to trigger events
89when the replay sequence is exceeded.
90
91d) expiry timer (XFRMA_ETIMER_THRESH)
92This is a timer value in milliseconds which is used as the nagle
93value to rate limit the events.
94
953) Default configurations for the parameters:
96----------------------------------------------
97
98By default these events should be turned off unless there is
99at least one listener registered to listen to the multicast
100group XFRMNLGRP_AEVENTS.
101
102Programs installing SAs will need to specify the two thresholds, however,
103in order to not change existing applications such as racoon
104we also provide default threshold values for these different parameters
105in case they are not specified.
106
107the two sysctls/proc entries are:
108a) /proc/sys/net/core/sysctl_xfrm_aevent_etime
109used to provide default values for the XFRMA_ETIMER_THRESH in incremental
110units of time of 100ms. The default is 10 (1 second)
111
112b) /proc/sys/net/core/sysctl_xfrm_aevent_rseqth
113used to provide default values for XFRMA_REPLAY_THRESH parameter
114in incremental packet count. The default is two packets.
115
1164) Message types
117----------------
118
119a) XFRM_MSG_GETAE issued by user-->kernel.
120XFRM_MSG_GETAE does not carry any TLVs.
121The response is a XFRM_MSG_NEWAE which is formatted based on what
122XFRM_MSG_GETAE queried for.
123The response will always have XFRMA_LTIME_VAL and XFRMA_REPLAY_VAL TLVs.
124*if XFRM_AE_RTHR flag is set, then XFRMA_REPLAY_THRESH is also retrieved
125*if XFRM_AE_ETHR flag is set, then XFRMA_ETIMER_THRESH is also retrieved
126
127b) XFRM_MSG_NEWAE is issued by either user space to configure
128or kernel to announce events or respond to a XFRM_MSG_GETAE.
129
130i) user --> kernel to configure a specific SA.
131any of the values or threshold parameters can be updated by passing the
132appropriate TLV.
133A response is issued back to the sender in user space to indicate success
134or failure.
135In the case of success, additionally an event with
136XFRM_MSG_NEWAE is also issued to any listeners as described in iii).
137
138ii) kernel->user direction as a response to XFRM_MSG_GETAE
139The response will always have XFRMA_LTIME_VAL and XFRMA_REPLAY_VAL TLVs.
140The threshold TLVs will be included if explicitly requested in
141the XFRM_MSG_GETAE message.
142
143iii) kernel->user to report as event if someone sets any values or
144thresholds for an SA using XFRM_MSG_NEWAE (as described in #i above).
145In such a case XFRM_AE_CU flag is set to inform the user that
146the change happened as a result of an update.
147The message will always have XFRMA_LTIME_VAL and XFRMA_REPLAY_VAL TLVs.
148
149iv) kernel->user to report event when replay threshold or a timeout
150is exceeded.
151In such a case either XFRM_AE_CR (replay exceeded) or XFRM_AE_CE (timeout
152happened) is set to inform the user what happened.
153Note the two flags are mutually exclusive.
154The message will always have XFRMA_LTIME_VAL and XFRMA_REPLAY_VAL TLVs.
155
156Exceptions to threshold settings
157--------------------------------
158
159If you have an SA that is getting hit by traffic in bursts such that
160there is a period where the timer threshold expires with no packets
161seen, then an odd behavior is seen as follows:
162The first packet arrival after a timer expiry will trigger a timeout
163aevent; i.e we dont wait for a timeout period or a packet threshold
164to be reached. This is done for simplicity and efficiency reasons.
165
166-JHS
diff --git a/Documentation/pcmcia/driver-changes.txt b/Documentation/pcmcia/driver-changes.txt
index 97420f08c786..4739c5c3face 100644
--- a/Documentation/pcmcia/driver-changes.txt
+++ b/Documentation/pcmcia/driver-changes.txt
@@ -1,5 +1,11 @@
1This file details changes in 2.6 which affect PCMCIA card driver authors: 1This file details changes in 2.6 which affect PCMCIA card driver authors:
2 2
3* New release helper (as of 2.6.17)
4 Instead of calling pcmcia_release_{configuration,io,irq,win}, all that's
5 necessary now is calling pcmcia_disable_device. As there is no valid
6 reason left to call pcmcia_release_io and pcmcia_release_irq, the
7 exports for them were removed.
8
3* Unify detach and REMOVAL event code, as well as attach and INSERTION 9* Unify detach and REMOVAL event code, as well as attach and INSERTION
4 code (as of 2.6.16) 10 code (as of 2.6.16)
5 void (*remove) (struct pcmcia_device *dev); 11 void (*remove) (struct pcmcia_device *dev);
diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt
index ee551c6ea235..217e51768b87 100644
--- a/Documentation/powerpc/booting-without-of.txt
+++ b/Documentation/powerpc/booting-without-of.txt
@@ -719,6 +719,11 @@ address which can extend beyond that limit.
719 - model : this is your board name/model 719 - model : this is your board name/model
720 - #address-cells : address representation for "root" devices 720 - #address-cells : address representation for "root" devices
721 - #size-cells: the size representation for "root" devices 721 - #size-cells: the size representation for "root" devices
722 - device_type : This property shouldn't be necessary. However, if
723 you decide to create a device_type for your root node, make sure it
724 is _not_ "chrp" unless your platform is a pSeries or PAPR compliant
725 one for 64-bit, or a CHRP-type machine for 32-bit as this will
726 matched by the kernel this way.
722 727
723 Additionally, some recommended properties are: 728 Additionally, some recommended properties are:
724 729
diff --git a/Documentation/scsi/scsi_eh.txt b/Documentation/scsi/scsi_eh.txt
index 331afd791cbb..ce767b90bb0d 100644
--- a/Documentation/scsi/scsi_eh.txt
+++ b/Documentation/scsi/scsi_eh.txt
@@ -19,9 +19,9 @@ TABLE OF CONTENTS
19 [2-1-1] Overview 19 [2-1-1] Overview
20 [2-1-2] Flow of scmds through EH 20 [2-1-2] Flow of scmds through EH
21 [2-1-3] Flow of control 21 [2-1-3] Flow of control
22 [2-2] EH through hostt->eh_strategy_handler() 22 [2-2] EH through transportt->eh_strategy_handler()
23 [2-2-1] Pre hostt->eh_strategy_handler() SCSI midlayer conditions 23 [2-2-1] Pre transportt->eh_strategy_handler() SCSI midlayer conditions
24 [2-2-2] Post hostt->eh_strategy_handler() SCSI midlayer conditions 24 [2-2-2] Post transportt->eh_strategy_handler() SCSI midlayer conditions
25 [2-2-3] Things to consider 25 [2-2-3] Things to consider
26 26
27 27
@@ -413,9 +413,9 @@ scmd->allowed.
413 layer of failure of the scmds. 413 layer of failure of the scmds.
414 414
415 415
416[2-2] EH through hostt->eh_strategy_handler() 416[2-2] EH through transportt->eh_strategy_handler()
417 417
418 hostt->eh_strategy_handler() is invoked in the place of 418 transportt->eh_strategy_handler() is invoked in the place of
419scsi_unjam_host() and it is responsible for whole recovery process. 419scsi_unjam_host() and it is responsible for whole recovery process.
420On completion, the handler should have made lower layers forget about 420On completion, the handler should have made lower layers forget about
421all failed scmds and either ready for new commands or offline. Also, 421all failed scmds and either ready for new commands or offline. Also,
@@ -424,7 +424,7 @@ SCSI midlayer. IOW, of the steps described in [2-1-2], all steps
424except for #1 must be implemented by eh_strategy_handler(). 424except for #1 must be implemented by eh_strategy_handler().
425 425
426 426
427[2-2-1] Pre hostt->eh_strategy_handler() SCSI midlayer conditions 427[2-2-1] Pre transportt->eh_strategy_handler() SCSI midlayer conditions
428 428
429 The following conditions are true on entry to the handler. 429 The following conditions are true on entry to the handler.
430 430
@@ -437,7 +437,7 @@ except for #1 must be implemented by eh_strategy_handler().
437 - shost->host_failed == shost->host_busy 437 - shost->host_failed == shost->host_busy
438 438
439 439
440[2-2-2] Post hostt->eh_strategy_handler() SCSI midlayer conditions 440[2-2-2] Post transportt->eh_strategy_handler() SCSI midlayer conditions
441 441
442 The following conditions must be true on exit from the handler. 442 The following conditions must be true on exit from the handler.
443 443
diff --git a/Documentation/scsi/scsi_mid_low_api.txt b/Documentation/scsi/scsi_mid_low_api.txt
index 8bbae3e1abdf..75a535a975c3 100644
--- a/Documentation/scsi/scsi_mid_low_api.txt
+++ b/Documentation/scsi/scsi_mid_low_api.txt
@@ -804,7 +804,6 @@ Summary:
804 eh_bus_reset_handler - issue SCSI bus reset 804 eh_bus_reset_handler - issue SCSI bus reset
805 eh_device_reset_handler - issue SCSI device reset 805 eh_device_reset_handler - issue SCSI device reset
806 eh_host_reset_handler - reset host (host bus adapter) 806 eh_host_reset_handler - reset host (host bus adapter)
807 eh_strategy_handler - driver supplied alternate to scsi_unjam_host()
808 info - supply information about given host 807 info - supply information about given host
809 ioctl - driver can respond to ioctls 808 ioctl - driver can respond to ioctls
810 proc_info - supports /proc/scsi/{driver_name}/{host_no} 809 proc_info - supports /proc/scsi/{driver_name}/{host_no}
@@ -970,24 +969,6 @@ Details:
970 969
971 970
972/** 971/**
973 * eh_strategy_handler - driver supplied alternate to scsi_unjam_host()
974 * @shp: host on which error has occurred
975 *
976 * Returns TRUE if host unjammed, else FALSE.
977 *
978 * Locks: none
979 *
980 * Calling context: kernel thread
981 *
982 * Notes: Invoked from scsi_eh thread. LLD supplied alternate to
983 * scsi_unjam_host() found in scsi_error.c
984 *
985 * Optionally defined in: LLD
986 **/
987 int eh_strategy_handler(struct Scsi_Host * shp)
988
989
990/**
991 * info - supply information about given host: driver name plus data 972 * info - supply information about given host: driver name plus data
992 * to distinguish given host 973 * to distinguish given host
993 * @shp: host to supply information about 974 * @shp: host to supply information about
diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index 42ef9970bc86..df82116a9f26 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -3,14 +3,11 @@
3 -------------------- 3 --------------------
4 4
5 5
6 $Id: driver,v 1.10 2002/07/22 15:27:30 rmk Exp $
7
8
9This document is meant as a brief overview of some aspects of the new serial 6This document is meant as a brief overview of some aspects of the new serial
10driver. It is not complete, any questions you have should be directed to 7driver. It is not complete, any questions you have should be directed to
11<rmk@arm.linux.org.uk> 8<rmk@arm.linux.org.uk>
12 9
13The reference implementation is contained within serial_amba.c. 10The reference implementation is contained within amba_pl011.c.
14 11
15 12
16 13
@@ -31,6 +28,11 @@ The serial core provides a few helper functions. This includes identifing
31the correct port structure (via uart_get_console) and decoding command line 28the correct port structure (via uart_get_console) and decoding command line
32arguments (uart_parse_options). 29arguments (uart_parse_options).
33 30
31There is also a helper function (uart_write_console) which performs a
32character by character write, translating newlines to CRLF sequences.
33Driver writers are recommended to use this function rather than implementing
34their own version.
35
34 36
35Locking 37Locking
36------- 38-------
@@ -86,6 +88,7 @@ hardware.
86 - TIOCM_DTR DTR signal. 88 - TIOCM_DTR DTR signal.
87 - TIOCM_OUT1 OUT1 signal. 89 - TIOCM_OUT1 OUT1 signal.
88 - TIOCM_OUT2 OUT2 signal. 90 - TIOCM_OUT2 OUT2 signal.
91 - TIOCM_LOOP Set the port into loopback mode.
89 If the appropriate bit is set, the signal should be driven 92 If the appropriate bit is set, the signal should be driven
90 active. If the bit is clear, the signal should be driven 93 active. If the bit is clear, the signal should be driven
91 inactive. 94 inactive.
@@ -141,6 +144,10 @@ hardware.
141 enable_ms(port) 144 enable_ms(port)
142 Enable the modem status interrupts. 145 Enable the modem status interrupts.
143 146
147 This method may be called multiple times. Modem status
148 interrupts should be disabled when the shutdown method is
149 called.
150
144 Locking: port->lock taken. 151 Locking: port->lock taken.
145 Interrupts: locally disabled. 152 Interrupts: locally disabled.
146 This call must not sleep 153 This call must not sleep
@@ -160,6 +167,8 @@ hardware.
160 state. Enable the port for reception. It should not activate 167 state. Enable the port for reception. It should not activate
161 RTS nor DTR; this will be done via a separate call to set_mctrl. 168 RTS nor DTR; this will be done via a separate call to set_mctrl.
162 169
170 This method will only be called when the port is initially opened.
171
163 Locking: port_sem taken. 172 Locking: port_sem taken.
164 Interrupts: globally disabled. 173 Interrupts: globally disabled.
165 174
@@ -169,6 +178,11 @@ hardware.
169 RTS nor DTR; this will have already been done via a separate 178 RTS nor DTR; this will have already been done via a separate
170 call to set_mctrl. 179 call to set_mctrl.
171 180
181 Drivers must not access port->info once this call has completed.
182
183 This method will only be called when there are no more users of
184 this port.
185
172 Locking: port_sem taken. 186 Locking: port_sem taken.
173 Interrupts: caller dependent. 187 Interrupts: caller dependent.
174 188
diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 1def6049784c..0ee2c7dfc482 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -120,6 +120,34 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
120 enable - enable card 120 enable - enable card
121 - Default: enabled, for PCI and ISA PnP cards 121 - Default: enabled, for PCI and ISA PnP cards
122 122
123 Module snd-adlib
124 ----------------
125
126 Module for AdLib FM cards.
127
128 port - port # for OPL chip
129
130 This module supports multiple cards. It does not support autoprobe, so
131 the port must be specified. For actual AdLib FM cards it will be 0x388.
132 Note that this card does not have PCM support and no mixer; only FM
133 synthesis.
134
135 Make sure you have "sbiload" from the alsa-tools package available and,
136 after loading the module, find out the assigned ALSA sequencer port
137 number through "sbiload -l". Example output:
138
139 Port Client name Port name
140 64:0 OPL2 FM synth OPL2 FM Port
141
142 Load the std.sb and drums.sb patches also supplied by sbiload:
143
144 sbiload -p 64:0 std.sb drums.sb
145
146 If you use this driver to drive an OPL3, you can use std.o3 and drums.o3
147 instead. To have the card produce sound, use aplaymidi from alsa-utils:
148
149 aplaymidi -p 64:0 foo.mid
150
123 Module snd-ad1816a 151 Module snd-ad1816a
124 ------------------ 152 ------------------
125 153
@@ -190,6 +218,15 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
190 218
191 The power-management is supported. 219 The power-management is supported.
192 220
221 Module snd-als300
222 -----------------
223
224 Module for Avance Logic ALS300 and ALS300+
225
226 This module supports multiple cards.
227
228 The power-management is supported.
229
193 Module snd-als4000 230 Module snd-als4000
194 ------------------ 231 ------------------
195 232
@@ -701,6 +738,7 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
701 uniwill 3-jack 738 uniwill 3-jack
702 F1734 2-jack 739 F1734 2-jack
703 lg LG laptop (m1 express dual) 740 lg LG laptop (m1 express dual)
741 lg-lw LG LW20 laptop
704 test for testing/debugging purpose, almost all controls can be 742 test for testing/debugging purpose, almost all controls can be
705 adjusted. Appearing only when compiled with 743 adjusted. Appearing only when compiled with
706 $CONFIG_SND_DEBUG=y 744 $CONFIG_SND_DEBUG=y
@@ -1013,6 +1051,23 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
1013 1051
1014 The power-management is supported. 1052 The power-management is supported.
1015 1053
1054 Module snd-miro
1055 ---------------
1056
1057 Module for Miro soundcards: miroSOUND PCM 1 pro,
1058 miroSOUND PCM 12,
1059 miroSOUND PCM 20 Radio.
1060
1061 port - Port # (0x530,0x604,0xe80,0xf40)
1062 irq - IRQ # (5,7,9,10,11)
1063 dma1 - 1st dma # (0,1,3)
1064 dma2 - 2nd dma # (0,1)
1065 mpu_port - MPU-401 port # (0x300,0x310,0x320,0x330)
1066 mpu_irq - MPU-401 irq # (5,7,9,10)
1067 fm_port - FM Port # (0x388)
1068 wss - enable WSS mode
1069 ide - enable onboard ide support
1070
1016 Module snd-mixart 1071 Module snd-mixart
1017 ----------------- 1072 -----------------
1018 1073
@@ -1202,6 +1257,20 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
1202 1257
1203 The power-management is supported. 1258 The power-management is supported.
1204 1259
1260 Module snd-riptide
1261 ------------------
1262
1263 Module for Conexant Riptide chip
1264
1265 joystick_port - Joystick port # (default: 0x200)
1266 mpu_port - MPU401 port # (default: 0x330)
1267 opl3_port - OPL3 port # (default: 0x388)
1268
1269 This module supports multiple cards.
1270 The driver requires the firmware loader support on kernel.
1271 You need to install the firmware file "riptide.hex" to the standard
1272 firmware path (e.g. /lib/firmware).
1273
1205 Module snd-rme32 1274 Module snd-rme32
1206 ---------------- 1275 ----------------
1207 1276
diff --git a/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl b/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
index 6feef9e82b63..68eeebc17ff4 100644
--- a/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
+++ b/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
@@ -1123,8 +1123,8 @@
1123 if ((err = pci_enable_device(pci)) < 0) 1123 if ((err = pci_enable_device(pci)) < 0)
1124 return err; 1124 return err;
1125 /* check PCI availability (28bit DMA) */ 1125 /* check PCI availability (28bit DMA) */
1126 if (pci_set_dma_mask(pci, 0x0fffffff) < 0 || 1126 if (pci_set_dma_mask(pci, DMA_28BIT_MASK) < 0 ||
1127 pci_set_consistent_dma_mask(pci, 0x0fffffff) < 0) { 1127 pci_set_consistent_dma_mask(pci, DMA_28BIT_MASK) < 0) {
1128 printk(KERN_ERR "error to set 28bit mask DMA\n"); 1128 printk(KERN_ERR "error to set 28bit mask DMA\n");
1129 pci_disable_device(pci); 1129 pci_disable_device(pci);
1130 return -ENXIO; 1130 return -ENXIO;
@@ -1216,7 +1216,7 @@
1216 The allocation of PCI resources is done in the 1216 The allocation of PCI resources is done in the
1217 <function>probe()</function> function, and usually an extra 1217 <function>probe()</function> function, and usually an extra
1218 <function>xxx_create()</function> function is written for this 1218 <function>xxx_create()</function> function is written for this
1219 purpose. 1219 purpose.
1220 </para> 1220 </para>
1221 1221
1222 <para> 1222 <para>
@@ -1225,7 +1225,7 @@
1225 allocating resources. Also, you need to set the proper PCI DMA 1225 allocating resources. Also, you need to set the proper PCI DMA
1226 mask to limit the accessed i/o range. In some cases, you might 1226 mask to limit the accessed i/o range. In some cases, you might
1227 need to call <function>pci_set_master()</function> function, 1227 need to call <function>pci_set_master()</function> function,
1228 too. 1228 too.
1229 </para> 1229 </para>
1230 1230
1231 <para> 1231 <para>
@@ -1236,8 +1236,8 @@
1236<![CDATA[ 1236<![CDATA[
1237 if ((err = pci_enable_device(pci)) < 0) 1237 if ((err = pci_enable_device(pci)) < 0)
1238 return err; 1238 return err;
1239 if (pci_set_dma_mask(pci, 0x0fffffff) < 0 || 1239 if (pci_set_dma_mask(pci, DMA_28BIT_MASK) < 0 ||
1240 pci_set_consistent_dma_mask(pci, 0x0fffffff) < 0) { 1240 pci_set_consistent_dma_mask(pci, DMA_28BIT_MASK) < 0) {
1241 printk(KERN_ERR "error to set 28bit mask DMA\n"); 1241 printk(KERN_ERR "error to set 28bit mask DMA\n");
1242 pci_disable_device(pci); 1242 pci_disable_device(pci);
1243 return -ENXIO; 1243 return -ENXIO;
@@ -1256,13 +1256,13 @@
1256 functions. Unlike ALSA ver.0.5.x., there are no helpers for 1256 functions. Unlike ALSA ver.0.5.x., there are no helpers for
1257 that. And these resources must be released in the destructor 1257 that. And these resources must be released in the destructor
1258 function (see below). Also, on ALSA 0.9.x, you don't need to 1258 function (see below). Also, on ALSA 0.9.x, you don't need to
1259 allocate (pseudo-)DMA for PCI like ALSA 0.5.x. 1259 allocate (pseudo-)DMA for PCI like ALSA 0.5.x.
1260 </para> 1260 </para>
1261 1261
1262 <para> 1262 <para>
1263 Now assume that this PCI device has an I/O port with 8 bytes 1263 Now assume that this PCI device has an I/O port with 8 bytes
1264 and an interrupt. Then struct <structname>mychip</structname> will have the 1264 and an interrupt. Then struct <structname>mychip</structname> will have the
1265 following fields: 1265 following fields:
1266 1266
1267 <informalexample> 1267 <informalexample>
1268 <programlisting> 1268 <programlisting>
diff --git a/Documentation/video4linux/CARDLIST.saa7134 b/Documentation/video4linux/CARDLIST.saa7134
index 8c7195455963..bca50903233f 100644
--- a/Documentation/video4linux/CARDLIST.saa7134
+++ b/Documentation/video4linux/CARDLIST.saa7134
@@ -52,7 +52,7 @@
52 51 -> ProVideo PV952 [1540:9524] 52 51 -> ProVideo PV952 [1540:9524]
53 52 -> AverMedia AverTV/305 [1461:2108] 53 52 -> AverMedia AverTV/305 [1461:2108]
54 53 -> ASUS TV-FM 7135 [1043:4845] 54 53 -> ASUS TV-FM 7135 [1043:4845]
55 54 -> LifeView FlyTV Platinum FM [5168:0214,1489:0214] 55 54 -> LifeView FlyTV Platinum FM / Gold [5168:0214,1489:0214,5168:0304]
56 55 -> LifeView FlyDVB-T DUO [5168:0306] 56 55 -> LifeView FlyDVB-T DUO [5168:0306]
57 56 -> Avermedia AVerTV 307 [1461:a70a] 57 56 -> Avermedia AVerTV 307 [1461:a70a]
58 57 -> Avermedia AVerTV GO 007 FM [1461:f31f] 58 57 -> Avermedia AVerTV GO 007 FM [1461:f31f]
@@ -84,7 +84,7 @@
84 83 -> Terratec Cinergy 250 PCI TV [153b:1160] 84 83 -> Terratec Cinergy 250 PCI TV [153b:1160]
85 84 -> LifeView FlyDVB Trio [5168:0319] 85 84 -> LifeView FlyDVB Trio [5168:0319]
86 85 -> AverTV DVB-T 777 [1461:2c05] 86 85 -> AverTV DVB-T 777 [1461:2c05]
87 86 -> LifeView FlyDVB-T [5168:0301] 87 86 -> LifeView FlyDVB-T / Genius VideoWonder DVB-T [5168:0301,1489:0301]
88 87 -> ADS Instant TV Duo Cardbus PTV331 [0331:1421] 88 87 -> ADS Instant TV Duo Cardbus PTV331 [0331:1421]
89 88 -> Tevion/KWorld DVB-T 220RF [17de:7201] 89 88 -> Tevion/KWorld DVB-T 220RF [17de:7201]
90 89 -> ELSA EX-VISION 700TV [1048:226c] 90 89 -> ELSA EX-VISION 700TV [1048:226c]
@@ -92,3 +92,4 @@
92 91 -> AVerMedia A169 B [1461:7360] 92 91 -> AVerMedia A169 B [1461:7360]
93 92 -> AVerMedia A169 B1 [1461:6360] 93 92 -> AVerMedia A169 B1 [1461:6360]
94 93 -> Medion 7134 Bridge #2 [16be:0005] 94 93 -> Medion 7134 Bridge #2 [16be:0005]
95 94 -> LifeView FlyDVB-T Hybrid Cardbus [5168:3306,5168:3502]
diff --git a/Documentation/usb/et61x251.txt b/Documentation/video4linux/et61x251.txt
index 29340282ab5f..29340282ab5f 100644
--- a/Documentation/usb/et61x251.txt
+++ b/Documentation/video4linux/et61x251.txt
diff --git a/Documentation/usb/ibmcam.txt b/Documentation/video4linux/ibmcam.txt
index c25003644131..4a40a2e99451 100644
--- a/Documentation/usb/ibmcam.txt
+++ b/Documentation/video4linux/ibmcam.txt
@@ -122,7 +122,7 @@ WHAT YOU NEED:
122- A Linux box with USB support (2.3/2.4; 2.2 w/backport may work) 122- A Linux box with USB support (2.3/2.4; 2.2 w/backport may work)
123 123
124- A Video4Linux compatible frame grabber program such as xawtv. 124- A Video4Linux compatible frame grabber program such as xawtv.
125 125
126HOW TO COMPILE THE DRIVER: 126HOW TO COMPILE THE DRIVER:
127 127
128You need to compile the driver only if you are a developer 128You need to compile the driver only if you are a developer
diff --git a/Documentation/usb/ov511.txt b/Documentation/video4linux/ov511.txt
index a7fc0432bff1..142741e3c578 100644
--- a/Documentation/usb/ov511.txt
+++ b/Documentation/video4linux/ov511.txt
@@ -9,7 +9,7 @@ INTRODUCTION:
9 9
10This is a driver for the OV511, a USB-only chip used in many "webcam" devices. 10This is a driver for the OV511, a USB-only chip used in many "webcam" devices.
11Any camera using the OV511/OV511+ and the OV6620/OV7610/20/20AE should work. 11Any camera using the OV511/OV511+ and the OV6620/OV7610/20/20AE should work.
12Video capture devices that use the Philips SAA7111A decoder also work. It 12Video capture devices that use the Philips SAA7111A decoder also work. It
13supports streaming and capture of color or monochrome video via the Video4Linux 13supports streaming and capture of color or monochrome video via the Video4Linux
14API. Most V4L apps are compatible with it. Most resolutions with a width and 14API. Most V4L apps are compatible with it. Most resolutions with a width and
15height that are a multiple of 8 are supported. 15height that are a multiple of 8 are supported.
@@ -52,15 +52,15 @@ from it:
52 52
53 chmod 666 /dev/video 53 chmod 666 /dev/video
54 chmod 666 /dev/video0 (if necessary) 54 chmod 666 /dev/video0 (if necessary)
55 55
56Now you are ready to run a video app! Both vidcat and xawtv work well for me 56Now you are ready to run a video app! Both vidcat and xawtv work well for me
57at 640x480. 57at 640x480.
58 58
59[Using vidcat:] 59[Using vidcat:]
60 60
61 vidcat -s 640x480 -p c > test.jpg 61 vidcat -s 640x480 -p c > test.jpg
62 xview test.jpg 62 xview test.jpg
63 63
64[Using xawtv:] 64[Using xawtv:]
65 65
66From the main xawtv directory: 66From the main xawtv directory:
@@ -70,7 +70,7 @@ From the main xawtv directory:
70 make 70 make
71 make install 71 make install
72 72
73Now you should be able to run xawtv. Right click for the options dialog. 73Now you should be able to run xawtv. Right click for the options dialog.
74 74
75MODULE PARAMETERS: 75MODULE PARAMETERS:
76 76
@@ -286,4 +286,3 @@ Randy Dunlap, and others. Big thanks to them for their pioneering work on that
286and the USB stack. Thanks to Bret Wallach for getting camera reg IO, ISOC, and 286and the USB stack. Thanks to Bret Wallach for getting camera reg IO, ISOC, and
287image capture working. Thanks to Orion Sky Lawlor, Kevin Moore, and Claudio 287image capture working. Thanks to Orion Sky Lawlor, Kevin Moore, and Claudio
288Matsuoka for their work as well. 288Matsuoka for their work as well.
289
diff --git a/Documentation/usb/se401.txt b/Documentation/video4linux/se401.txt
index 7b9d1c960a10..7b9d1c960a10 100644
--- a/Documentation/usb/se401.txt
+++ b/Documentation/video4linux/se401.txt
diff --git a/Documentation/usb/sn9c102.txt b/Documentation/video4linux/sn9c102.txt
index b957beae5607..142920bc011f 100644
--- a/Documentation/usb/sn9c102.txt
+++ b/Documentation/video4linux/sn9c102.txt
@@ -174,7 +174,7 @@ Module parameters are listed below:
174------------------------------------------------------------------------------- 174-------------------------------------------------------------------------------
175Name: video_nr 175Name: video_nr
176Type: short array (min = 0, max = 64) 176Type: short array (min = 0, max = 64)
177Syntax: <-1|n[,...]> 177Syntax: <-1|n[,...]>
178Description: Specify V4L2 minor mode number: 178Description: Specify V4L2 minor mode number:
179 -1 = use next available 179 -1 = use next available
180 n = use minor number n 180 n = use minor number n
@@ -187,7 +187,7 @@ Default: -1
187------------------------------------------------------------------------------- 187-------------------------------------------------------------------------------
188Name: force_munmap 188Name: force_munmap
189Type: bool array (min = 0, max = 64) 189Type: bool array (min = 0, max = 64)
190Syntax: <0|1[,...]> 190Syntax: <0|1[,...]>
191Description: Force the application to unmap previously mapped buffer memory 191Description: Force the application to unmap previously mapped buffer memory
192 before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not 192 before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not
193 all the applications support this feature. This parameter is 193 all the applications support this feature. This parameter is
@@ -206,7 +206,7 @@ Default: 2
206------------------------------------------------------------------------------- 206-------------------------------------------------------------------------------
207Name: debug 207Name: debug
208Type: ushort 208Type: ushort
209Syntax: <n> 209Syntax: <n>
210Description: Debugging information level, from 0 to 3: 210Description: Debugging information level, from 0 to 3:
211 0 = none (use carefully) 211 0 = none (use carefully)
212 1 = critical errors 212 1 = critical errors
@@ -267,7 +267,7 @@ The sysfs interface also provides the "frame_header" entry, which exports the
267frame header of the most recent requested and captured video frame. The header 267frame header of the most recent requested and captured video frame. The header
268is always 18-bytes long and is appended to every video frame by the SN9C10x 268is always 18-bytes long and is appended to every video frame by the SN9C10x
269controllers. As an example, this additional information can be used by the user 269controllers. As an example, this additional information can be used by the user
270application for implementing auto-exposure features via software. 270application for implementing auto-exposure features via software.
271 271
272The following table describes the frame header: 272The following table describes the frame header:
273 273
@@ -441,7 +441,7 @@ blue pixels in one video frame. Each pixel is associated with a 8-bit long
441value and is disposed in memory according to the pattern shown below: 441value and is disposed in memory according to the pattern shown below:
442 442
443B[0] G[1] B[2] G[3] ... B[m-2] G[m-1] 443B[0] G[1] B[2] G[3] ... B[m-2] G[m-1]
444G[m] R[m+1] G[m+2] R[m+2] ... G[2m-2] R[2m-1] 444G[m] R[m+1] G[m+2] R[m+2] ... G[2m-2] R[2m-1]
445... 445...
446... B[(n-1)(m-2)] G[(n-1)(m-1)] 446... B[(n-1)(m-2)] G[(n-1)(m-1)]
447... G[n(m-2)] R[n(m-1)] 447... G[n(m-2)] R[n(m-1)]
@@ -472,12 +472,12 @@ The pixel reference value is calculated as follows:
472The algorithm purely describes the conversion from compressed Bayer code used 472The algorithm purely describes the conversion from compressed Bayer code used
473in the SN9C10x chips to uncompressed Bayer. Additional steps are required to 473in the SN9C10x chips to uncompressed Bayer. Additional steps are required to
474convert this to a color image (i.e. a color interpolation algorithm). 474convert this to a color image (i.e. a color interpolation algorithm).
475 475
476The following Huffman codes have been found: 476The following Huffman codes have been found:
4770: +0 (relative to reference pixel value) 4770: +0 (relative to reference pixel value)
478100: +4 478100: +4
479101: -4? 479101: -4?
4801110xxxx: set absolute value to xxxx.0000 4801110xxxx: set absolute value to xxxx.0000
4811101: +11 4811101: +11
4821111: -11 4821111: -11
48311001: +20 48311001: +20
diff --git a/Documentation/usb/stv680.txt b/Documentation/video4linux/stv680.txt
index 6448041e7a37..4f8946f32f51 100644
--- a/Documentation/usb/stv680.txt
+++ b/Documentation/video4linux/stv680.txt
@@ -5,15 +5,15 @@ Copyright, 2001, Kevin Sisson
5 5
6INTRODUCTION: 6INTRODUCTION:
7 7
8STMicroelectronics produces the STV0680B chip, which comes in two 8STMicroelectronics produces the STV0680B chip, which comes in two
9types, -001 and -003. The -003 version allows the recording and downloading 9types, -001 and -003. The -003 version allows the recording and downloading
10of sound clips from the camera, and allows a flash attachment. Otherwise, 10of sound clips from the camera, and allows a flash attachment. Otherwise,
11it uses the same commands as the -001 version. Both versions support a 11it uses the same commands as the -001 version. Both versions support a
12variety of SDRAM sizes and sensors, allowing for a maximum of 26 VGA or 20 12variety of SDRAM sizes and sensors, allowing for a maximum of 26 VGA or 20
13CIF pictures. The STV0680 supports either a serial or a usb interface, and 13CIF pictures. The STV0680 supports either a serial or a usb interface, and
14video is possible through the usb interface. 14video is possible through the usb interface.
15 15
16The following cameras are known to work with this driver, although any 16The following cameras are known to work with this driver, although any
17camera with Vendor/Product codes of 0553/0202 should work: 17camera with Vendor/Product codes of 0553/0202 should work:
18 18
19Aiptek Pencam (various models) 19Aiptek Pencam (various models)
@@ -34,15 +34,15 @@ http://www.linux-usb.org
34MODULE OPTIONS: 34MODULE OPTIONS:
35 35
36When the driver is compiled as a module, you can set a "swapRGB=1" 36When the driver is compiled as a module, you can set a "swapRGB=1"
37option, if necessary, for those applications that require it 37option, if necessary, for those applications that require it
38(such as xawtv). However, the driver should detect and set this 38(such as xawtv). However, the driver should detect and set this
39automatically, so this option should not normally be used. 39automatically, so this option should not normally be used.
40 40
41 41
42KNOWN PROBLEMS: 42KNOWN PROBLEMS:
43 43
44The driver seems to work better with the usb-ohci than the usb-uhci host 44The driver seems to work better with the usb-ohci than the usb-uhci host
45controller driver. 45controller driver.
46 46
47HELP: 47HELP:
48 48
@@ -50,6 +50,4 @@ The latest info on this driver can be found at:
50http://personal.clt.bellsouth.net/~kjsisson or at 50http://personal.clt.bellsouth.net/~kjsisson or at
51http://stv0680-usb.sourceforge.net 51http://stv0680-usb.sourceforge.net
52 52
53Any questions to me can be send to: kjsisson@bellsouth.net 53Any questions to me can be send to: kjsisson@bellsouth.net \ No newline at end of file
54
55
diff --git a/Documentation/usb/w9968cf.txt b/Documentation/video4linux/w9968cf.txt
index 9d46cd0b19e3..3b704f2aae6d 100644
--- a/Documentation/usb/w9968cf.txt
+++ b/Documentation/video4linux/w9968cf.txt
@@ -1,5 +1,5 @@
1 1
2 W996[87]CF JPEG USB Dual Mode Camera Chip 2 W996[87]CF JPEG USB Dual Mode Camera Chip
3 Driver for Linux 2.6 (basic version) 3 Driver for Linux 2.6 (basic version)
4 ========================================= 4 =========================================
5 5
@@ -115,7 +115,7 @@ additional testing and full support, would be much appreciated.
115====================== 115======================
116For it to work properly, the driver needs kernel support for Video4Linux, USB 116For it to work properly, the driver needs kernel support for Video4Linux, USB
117and I2C, and the "ovcamchip" module for the image sensor. Make sure you are not 117and I2C, and the "ovcamchip" module for the image sensor. Make sure you are not
118actually using any external "ovcamchip" module, given that the W996[87]CF 118actually using any external "ovcamchip" module, given that the W996[87]CF
119driver depends on the version of the module present in the official kernels. 119driver depends on the version of the module present in the official kernels.
120 120
121The following options of the kernel configuration file must be enabled and 121The following options of the kernel configuration file must be enabled and
@@ -197,16 +197,16 @@ Note: The kernel must be compiled with the CONFIG_KMOD option
197 enabled for the 'ovcamchip' module to be loaded and for 197 enabled for the 'ovcamchip' module to be loaded and for
198 this parameter to be present. 198 this parameter to be present.
199------------------------------------------------------------------------------- 199-------------------------------------------------------------------------------
200Name: simcams 200Name: simcams
201Type: int 201Type: int
202Syntax: <n> 202Syntax: <n>
203Description: Number of cameras allowed to stream simultaneously. 203Description: Number of cameras allowed to stream simultaneously.
204 n may vary from 0 to 32. 204 n may vary from 0 to 32.
205Default: 32 205Default: 32
206------------------------------------------------------------------------------- 206-------------------------------------------------------------------------------
207Name: video_nr 207Name: video_nr
208Type: int array (min = 0, max = 32) 208Type: int array (min = 0, max = 32)
209Syntax: <-1|n[,...]> 209Syntax: <-1|n[,...]>
210Description: Specify V4L minor mode number. 210Description: Specify V4L minor mode number.
211 -1 = use next available 211 -1 = use next available
212 n = use minor number n 212 n = use minor number n
@@ -219,7 +219,7 @@ Default: -1
219------------------------------------------------------------------------------- 219-------------------------------------------------------------------------------
220Name: packet_size 220Name: packet_size
221Type: int array (min = 0, max = 32) 221Type: int array (min = 0, max = 32)
222Syntax: <n[,...]> 222Syntax: <n[,...]>
223Description: Specify the maximum data payload size in bytes for alternate 223Description: Specify the maximum data payload size in bytes for alternate
224 settings, for each device. n is scaled between 63 and 1023. 224 settings, for each device. n is scaled between 63 and 1023.
225Default: 1023 225Default: 1023
@@ -234,7 +234,7 @@ Default: 2
234------------------------------------------------------------------------------- 234-------------------------------------------------------------------------------
235Name: double_buffer 235Name: double_buffer
236Type: bool array (min = 0, max = 32) 236Type: bool array (min = 0, max = 32)
237Syntax: <0|1[,...]> 237Syntax: <0|1[,...]>
238Description: Hardware double buffering: 0 disabled, 1 enabled. 238Description: Hardware double buffering: 0 disabled, 1 enabled.
239 It should be enabled if you want smooth video output: if you 239 It should be enabled if you want smooth video output: if you
240 obtain out of sync. video, disable it, or try to 240 obtain out of sync. video, disable it, or try to
@@ -243,13 +243,13 @@ Default: 1 for every device.
243------------------------------------------------------------------------------- 243-------------------------------------------------------------------------------
244Name: clamping 244Name: clamping
245Type: bool array (min = 0, max = 32) 245Type: bool array (min = 0, max = 32)
246Syntax: <0|1[,...]> 246Syntax: <0|1[,...]>
247Description: Video data clamping: 0 disabled, 1 enabled. 247Description: Video data clamping: 0 disabled, 1 enabled.
248Default: 0 for every device. 248Default: 0 for every device.
249------------------------------------------------------------------------------- 249-------------------------------------------------------------------------------
250Name: filter_type 250Name: filter_type
251Type: int array (min = 0, max = 32) 251Type: int array (min = 0, max = 32)
252Syntax: <0|1|2[,...]> 252Syntax: <0|1|2[,...]>
253Description: Video filter type. 253Description: Video filter type.
254 0 none, 1 (1-2-1) 3-tap filter, 2 (2-3-6-3-2) 5-tap filter. 254 0 none, 1 (1-2-1) 3-tap filter, 2 (2-3-6-3-2) 5-tap filter.
255 The filter is used to reduce noise and aliasing artifacts 255 The filter is used to reduce noise and aliasing artifacts
@@ -258,13 +258,13 @@ Default: 0 for every device.
258------------------------------------------------------------------------------- 258-------------------------------------------------------------------------------
259Name: largeview 259Name: largeview
260Type: bool array (min = 0, max = 32) 260Type: bool array (min = 0, max = 32)
261Syntax: <0|1[,...]> 261Syntax: <0|1[,...]>
262Description: Large view: 0 disabled, 1 enabled. 262Description: Large view: 0 disabled, 1 enabled.
263Default: 1 for every device. 263Default: 1 for every device.
264------------------------------------------------------------------------------- 264-------------------------------------------------------------------------------
265Name: upscaling 265Name: upscaling
266Type: bool array (min = 0, max = 32) 266Type: bool array (min = 0, max = 32)
267Syntax: <0|1[,...]> 267Syntax: <0|1[,...]>
268Description: Software scaling (for non-compressed video only): 268Description: Software scaling (for non-compressed video only):
269 0 disabled, 1 enabled. 269 0 disabled, 1 enabled.
270 Disable it if you have a slow CPU or you don't have enough 270 Disable it if you have a slow CPU or you don't have enough
@@ -341,8 +341,8 @@ Default: 50 for every device.
341------------------------------------------------------------------------------- 341-------------------------------------------------------------------------------
342Name: bandingfilter 342Name: bandingfilter
343Type: bool array (min = 0, max = 32) 343Type: bool array (min = 0, max = 32)
344Syntax: <0|1[,...]> 344Syntax: <0|1[,...]>
345Description: Banding filter to reduce effects of fluorescent 345Description: Banding filter to reduce effects of fluorescent
346 lighting: 346 lighting:
347 0 disabled, 1 enabled. 347 0 disabled, 1 enabled.
348 This filter tries to reduce the pattern of horizontal 348 This filter tries to reduce the pattern of horizontal
@@ -374,7 +374,7 @@ Default: 0 for every device.
374------------------------------------------------------------------------------- 374-------------------------------------------------------------------------------
375Name: monochrome 375Name: monochrome
376Type: bool array (min = 0, max = 32) 376Type: bool array (min = 0, max = 32)
377Syntax: <0|1[,...]> 377Syntax: <0|1[,...]>
378Description: The image sensor is monochrome: 378Description: The image sensor is monochrome:
379 0 = no, 1 = yes 379 0 = no, 1 = yes
380Default: 0 for every device. 380Default: 0 for every device.
@@ -400,19 +400,19 @@ Default: 32768 for every device.
400------------------------------------------------------------------------------- 400-------------------------------------------------------------------------------
401Name: contrast 401Name: contrast
402Type: long array (min = 0, max = 32) 402Type: long array (min = 0, max = 32)
403Syntax: <n[,...]> 403Syntax: <n[,...]>
404Description: Set picture contrast (0-65535). 404Description: Set picture contrast (0-65535).
405Default: 50000 for every device. 405Default: 50000 for every device.
406------------------------------------------------------------------------------- 406-------------------------------------------------------------------------------
407Name: whiteness 407Name: whiteness
408Type: long array (min = 0, max = 32) 408Type: long array (min = 0, max = 32)
409Syntax: <n[,...]> 409Syntax: <n[,...]>
410Description: Set picture whiteness (0-65535). 410Description: Set picture whiteness (0-65535).
411Default: 32768 for every device. 411Default: 32768 for every device.
412------------------------------------------------------------------------------- 412-------------------------------------------------------------------------------
413Name: debug 413Name: debug
414Type: int 414Type: int
415Syntax: <n> 415Syntax: <n>
416Description: Debugging information level, from 0 to 6: 416Description: Debugging information level, from 0 to 6:
417 0 = none (use carefully) 417 0 = none (use carefully)
418 1 = critical errors 418 1 = critical errors
diff --git a/Documentation/usb/zc0301.txt b/Documentation/video4linux/zc0301.txt
index f55262c6733b..f55262c6733b 100644
--- a/Documentation/usb/zc0301.txt
+++ b/Documentation/video4linux/zc0301.txt
diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt
index 1ad9af1ca4d0..2803f63c1a27 100644
--- a/Documentation/vm/hugetlbpage.txt
+++ b/Documentation/vm/hugetlbpage.txt
@@ -27,7 +27,7 @@ number of free hugetlb pages at any time. It also displays information about
27the configured hugepage size - this is needed for generating the proper 27the configured hugepage size - this is needed for generating the proper
28alignment and size of the arguments to the above system calls. 28alignment and size of the arguments to the above system calls.
29 29
30The output of "cat /proc/meminfo" will have output like: 30The output of "cat /proc/meminfo" will have lines like:
31 31
32..... 32.....
33HugePages_Total: xxx 33HugePages_Total: xxx
@@ -42,11 +42,11 @@ pages in the kernel. Super user can dynamically request more (or free some
42pre-configured) hugepages. 42pre-configured) hugepages.
43The allocation (or deallocation) of hugetlb pages is possible only if there are 43The allocation (or deallocation) of hugetlb pages is possible only if there are
44enough physically contiguous free pages in system (freeing of hugepages is 44enough physically contiguous free pages in system (freeing of hugepages is
45possible only if there are enough hugetlb pages free that can be transfered 45possible only if there are enough hugetlb pages free that can be transferred
46back to regular memory pool). 46back to regular memory pool).
47 47
48Pages that are used as hugetlb pages are reserved inside the kernel and can 48Pages that are used as hugetlb pages are reserved inside the kernel and cannot
49not be used for other purposes. 49be used for other purposes.
50 50
51Once the kernel with Hugetlb page support is built and running, a user can 51Once the kernel with Hugetlb page support is built and running, a user can
52use either the mmap system call or shared memory system calls to start using 52use either the mmap system call or shared memory system calls to start using
@@ -60,7 +60,7 @@ Use the following command to dynamically allocate/deallocate hugepages:
60This command will try to configure 20 hugepages in the system. The success 60This command will try to configure 20 hugepages in the system. The success
61or failure of allocation depends on the amount of physically contiguous 61or failure of allocation depends on the amount of physically contiguous
62memory that is preset in system at this time. System administrators may want 62memory that is preset in system at this time. System administrators may want
63to put this command in one of the local rc init file. This will enable the 63to put this command in one of the local rc init files. This will enable the
64kernel to request huge pages early in the boot process (when the possibility 64kernel to request huge pages early in the boot process (when the possibility
65of getting physical contiguous pages is still very high). 65of getting physical contiguous pages is still very high).
66 66
@@ -78,8 +78,8 @@ the uid and gid of the current process are taken. The mode option sets the
78mode of root of file system to value & 0777. This value is given in octal. 78mode of root of file system to value & 0777. This value is given in octal.
79By default the value 0755 is picked. The size option sets the maximum value of 79By default the value 0755 is picked. The size option sets the maximum value of
80memory (huge pages) allowed for that filesystem (/mnt/huge). The size is 80memory (huge pages) allowed for that filesystem (/mnt/huge). The size is
81rounded down to HPAGE_SIZE. The option nr_inode sets the maximum number of 81rounded down to HPAGE_SIZE. The option nr_inodes sets the maximum number of
82inodes that /mnt/huge can use. If the size or nr_inode options are not 82inodes that /mnt/huge can use. If the size or nr_inodes options are not
83provided on command line then no limits are set. For size and nr_inodes 83provided on command line then no limits are set. For size and nr_inodes
84options, you can use [G|g]/[M|m]/[K|k] to represent giga/mega/kilo. For 84options, you can use [G|g]/[M|m]/[K|k] to represent giga/mega/kilo. For
85example, size=2K has the same meaning as size=2048. An example is given at 85example, size=2K has the same meaning as size=2048. An example is given at
@@ -88,7 +88,7 @@ the end of this document.
88read and write system calls are not supported on files that reside on hugetlb 88read and write system calls are not supported on files that reside on hugetlb
89file systems. 89file systems.
90 90
91A regular chown, chgrp and chmod commands (with right permissions) could be 91Regular chown, chgrp, and chmod commands (with right permissions) could be
92used to change the file attributes on hugetlbfs. 92used to change the file attributes on hugetlbfs.
93 93
94Also, it is important to note that no such mount command is required if the 94Also, it is important to note that no such mount command is required if the
@@ -96,8 +96,8 @@ applications are going to use only shmat/shmget system calls. Users who
96wish to use hugetlb page via shared memory segment should be a member of 96wish to use hugetlb page via shared memory segment should be a member of
97a supplementary group and system admin needs to configure that gid into 97a supplementary group and system admin needs to configure that gid into
98/proc/sys/vm/hugetlb_shm_group. It is possible for same or different 98/proc/sys/vm/hugetlb_shm_group. It is possible for same or different
99applications to use any combination of mmaps and shm* calls. Though the 99applications to use any combination of mmaps and shm* calls, though the
100mount of filesystem will be required for using mmaps. 100mount of filesystem will be required for using mmap calls.
101 101
102******************************************************************* 102*******************************************************************
103 103
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt
index 1921353259ae..f2cd6ef53ff3 100644
--- a/Documentation/x86_64/boot-options.txt
+++ b/Documentation/x86_64/boot-options.txt
@@ -151,6 +151,11 @@ NUMA
151 151
152 numa=fake=X Fake X nodes and ignore NUMA setup of the actual machine. 152 numa=fake=X Fake X nodes and ignore NUMA setup of the actual machine.
153 153
154 numa=hotadd=percent
155 Only allow hotadd memory to preallocate page structures upto
156 percent of already available memory.
157 numa=hotadd=0 will disable hotadd memory.
158
154ACPI 159ACPI
155 160
156 acpi=off Don't enable ACPI 161 acpi=off Don't enable ACPI