diff options
Diffstat (limited to 'include/scsi/sg.h')
-rw-r--r-- | include/scsi/sg.h | 61 |
1 files changed, 21 insertions, 40 deletions
diff --git a/include/scsi/sg.h b/include/scsi/sg.h index 0a487fe26d4f..519c49a0fc11 100644 --- a/include/scsi/sg.h +++ b/include/scsi/sg.h | |||
@@ -11,26 +11,10 @@ | |||
11 | Original driver (sg.h): | 11 | Original driver (sg.h): |
12 | * Copyright (C) 1992 Lawrence Foard | 12 | * Copyright (C) 1992 Lawrence Foard |
13 | Version 2 and 3 extensions to driver: | 13 | Version 2 and 3 extensions to driver: |
14 | * Copyright (C) 1998 - 2003 Douglas Gilbert | 14 | * Copyright (C) 1998 - 2006 Douglas Gilbert |
15 | 15 | ||
16 | Version: 3.5.29 (20030529) | 16 | Version: 3.5.34 (20060920) |
17 | This version is for 2.5 series kernels. | 17 | This version is for 2.6 series kernels. |
18 | |||
19 | Changes since 3.5.28 (20030308) | ||
20 | - fix bug introduced in version 3.1.24 (last segment of sgat list) | ||
21 | Changes since 3.5.27 (20020812) | ||
22 | - remove procfs entries: hosts, host_hdr + host_strs (now in sysfs) | ||
23 | - add sysfs sg driver params: def_reserved_size, allow_dio, version | ||
24 | - new boot option: "sg_allow_dio" and module parameter: "allow_dio" | ||
25 | - multiple internal changes due to scsi subsystem rework | ||
26 | Changes since 3.5.26 (20020708) | ||
27 | - re-add direct IO using Kai Makisara's work | ||
28 | - re-tab to 8, start using C99-isms | ||
29 | - simplify memory management | ||
30 | Changes since 3.5.25 (20020504) | ||
31 | - driverfs additions | ||
32 | - copy_to/from_user() fixes [William Stinson] | ||
33 | - disable kiobufs support | ||
34 | 18 | ||
35 | For a full changelog see http://www.torque.net/sg | 19 | For a full changelog see http://www.torque.net/sg |
36 | 20 | ||
@@ -40,7 +24,7 @@ Map of SG verions to the Linux kernels in which they appear: | |||
40 | 2.1.40 2.2.20 | 24 | 2.1.40 2.2.20 |
41 | 3.0.x optional version 3 sg driver for 2.2 series | 25 | 3.0.x optional version 3 sg driver for 2.2 series |
42 | 3.1.17++ 2.4.0++ | 26 | 3.1.17++ 2.4.0++ |
43 | 3.5.23++ 2.5.0++ | 27 | 3.5.30++ 2.6.0++ |
44 | 28 | ||
45 | Major new features in SG 3.x driver (cf SG 2.x drivers) | 29 | Major new features in SG 3.x driver (cf SG 2.x drivers) |
46 | - SG_IO ioctl() combines function if write() and read() | 30 | - SG_IO ioctl() combines function if write() and read() |
@@ -51,14 +35,15 @@ Major new features in SG 3.x driver (cf SG 2.x drivers) | |||
51 | data into kernel buffers and then use the CPU to copy the data into the | 35 | data into kernel buffers and then use the CPU to copy the data into the |
52 | user space (vice versa for writes). That is called "indirect" IO due to | 36 | user space (vice versa for writes). That is called "indirect" IO due to |
53 | the double handling of data. There are two methods offered to remove the | 37 | the double handling of data. There are two methods offered to remove the |
54 | redundant copy: 1) direct IO which uses the kernel kiobuf mechanism and | 38 | redundant copy: 1) direct IO and 2) using the mmap() system call to map |
55 | 2) using the mmap() system call to map the reserve buffer (this driver has | 39 | the reserve buffer (this driver has one reserve buffer per fd) into the |
56 | one reserve buffer per fd) into the user space. Both have their advantages. | 40 | user space. Both have their advantages. |
57 | In terms of absolute speed mmap() is faster. If speed is not a concern, | 41 | In terms of absolute speed mmap() is faster. If speed is not a concern, |
58 | indirect IO should be fine. Read the documentation for more information. | 42 | indirect IO should be fine. Read the documentation for more information. |
59 | 43 | ||
60 | ** N.B. To use direct IO 'echo 1 > /proc/scsi/sg/allow_dio' may be | 44 | ** N.B. To use direct IO 'echo 1 > /proc/scsi/sg/allow_dio' or |
61 | needed. That pseudo file's content is defaulted to 0. ** | 45 | 'echo 1 > /sys/module/sg/parameters/allow_dio' is needed. |
46 | That attribute is 0 by default. ** | ||
62 | 47 | ||
63 | Historical note: this SCSI pass-through driver has been known as "sg" for | 48 | Historical note: this SCSI pass-through driver has been known as "sg" for |
64 | a decade. In broader kernel discussions "sg" is used to refer to scatter | 49 | a decade. In broader kernel discussions "sg" is used to refer to scatter |
@@ -72,20 +57,17 @@ Major new features in SG 3.x driver (cf SG 2.x drivers) | |||
72 | http://www.torque.net/sg/p/sg_v3_ho.html | 57 | http://www.torque.net/sg/p/sg_v3_ho.html |
73 | This is a rendering from DocBook source [change the extension to "sgml" | 58 | This is a rendering from DocBook source [change the extension to "sgml" |
74 | or "xml"]. There are renderings in "ps", "pdf", "rtf" and "txt" (soon). | 59 | or "xml"]. There are renderings in "ps", "pdf", "rtf" and "txt" (soon). |
60 | The SG_IO ioctl is now found in other parts kernel (e.g. the block layer). | ||
61 | For more information see http://www.torque.net/sg/sg_io.html | ||
75 | 62 | ||
76 | The older, version 2 documents discuss the original sg interface in detail: | 63 | The older, version 2 documents discuss the original sg interface in detail: |
77 | http://www.torque.net/sg/p/scsi-generic.txt | 64 | http://www.torque.net/sg/p/scsi-generic.txt |
78 | http://www.torque.net/sg/p/scsi-generic_long.txt | 65 | http://www.torque.net/sg/p/scsi-generic_long.txt |
79 | A version of this document (potentially out of date) may also be found in | 66 | Also available: <kernel_source>/Documentation/scsi/scsi-generic.txt |
80 | the kernel source tree, probably at: | ||
81 | Documentation/scsi/scsi-generic.txt . | ||
82 | 67 | ||
83 | Utility and test programs are available at the sg web site. They are | 68 | Utility and test programs are available at the sg web site. They are |
84 | bundled as sg_utils (for the lk 2.2 series) and sg3_utils (for the | 69 | packaged as sg3_utils (for the lk 2.4 and 2.6 series) and sg_utils |
85 | lk 2.4 series). | 70 | (for the lk 2.2 series). |
86 | |||
87 | There is a HOWTO on the Linux SCSI subsystem in the lk 2.4 series at: | ||
88 | http://www.linuxdoc.org/HOWTO/SCSI-2.4-HOWTO | ||
89 | */ | 71 | */ |
90 | 72 | ||
91 | 73 | ||
@@ -238,13 +220,12 @@ typedef struct sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */ | |||
238 | #define SG_GET_ACCESS_COUNT 0x2289 | 220 | #define SG_GET_ACCESS_COUNT 0x2289 |
239 | 221 | ||
240 | 222 | ||
241 | #define SG_SCATTER_SZ (8 * 4096) /* PAGE_SIZE not available to user */ | 223 | #define SG_SCATTER_SZ (8 * 4096) |
242 | /* Largest size (in bytes) a single scatter-gather list element can have. | 224 | /* Largest size (in bytes) a single scatter-gather list element can have. |
243 | The value must be a power of 2 and <= (PAGE_SIZE * 32) [131072 bytes on | 225 | The value used by the driver is 'max(SG_SCATTER_SZ, PAGE_SIZE)'. |
244 | i386]. The minimum value is PAGE_SIZE. If scatter-gather not supported | 226 | This value should be a power of 2 (and may be rounded up internally). |
245 | by adapter then this value is the largest data block that can be | 227 | If scatter-gather is not supported by adapter then this value is the |
246 | read/written by a single scsi command. The user can find the value of | 228 | largest data block that can be read/written by a single scsi command. */ |
247 | PAGE_SIZE by calling getpagesize() defined in unistd.h . */ | ||
248 | 229 | ||
249 | #define SG_DEFAULT_RETRIES 0 | 230 | #define SG_DEFAULT_RETRIES 0 |
250 | 231 | ||