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authorLinus Torvalds <torvalds@linux-foundation.org>2008-07-14 16:43:24 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-14 16:43:24 -0400
commita3da5bf84a97d48cfaf66c6842470fc403da5121 (patch)
treecdf66c0cff8c61eedd60601fc9dffdd1ed39b880 /Documentation
parent3b23e665b68387f5ee7b21f7b75ceea4d9acae4a (diff)
parentd59fdcf2ac501de99c3dfb452af5e254d4342886 (diff)
Merge branch 'x86/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (821 commits) x86: make 64bit hpet_set_mapping to use ioremap too, v2 x86: get x86_phys_bits early x86: max_low_pfn_mapped fix #4 x86: change _node_to_cpumask_ptr to return const ptr x86: I/O APIC: remove an IRQ2-mask hack x86: fix numaq_tsc_disable calling x86, e820: remove end_user_pfn x86: max_low_pfn_mapped fix, #3 x86: max_low_pfn_mapped fix, #2 x86: max_low_pfn_mapped fix, #1 x86_64: fix delayed signals x86: remove conflicting nx6325 and nx6125 quirks x86: Recover timer_ack lost in the merge of the NMI watchdog x86: I/O APIC: Never configure IRQ2 x86: L-APIC: Always fully configure IRQ0 x86: L-APIC: Set IRQ0 as edge-triggered x86: merge dwarf2 headers x86: use AS_CFI instead of UNWIND_INFO x86: use ignore macro instead of hash comment x86: use matching CFI_ENDPROC ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-firmware-memmap71
-rw-r--r--Documentation/kdump/kdump.txt2
-rw-r--r--Documentation/kernel-parameters.txt37
-rw-r--r--Documentation/nmi_watchdog.txt16
-rw-r--r--Documentation/x86/i386/IO-APIC.txt (renamed from Documentation/i386/IO-APIC.txt)0
-rw-r--r--Documentation/x86/i386/boot.txt (renamed from Documentation/i386/boot.txt)79
-rw-r--r--Documentation/x86/i386/usb-legacy-support.txt (renamed from Documentation/i386/usb-legacy-support.txt)0
-rw-r--r--Documentation/x86/i386/zero-page.txt (renamed from Documentation/i386/zero-page.txt)0
-rw-r--r--Documentation/x86/x86_64/00-INDEX (renamed from Documentation/x86_64/00-INDEX)0
-rw-r--r--Documentation/x86/x86_64/boot-options.txt (renamed from Documentation/x86_64/boot-options.txt)0
-rw-r--r--Documentation/x86/x86_64/cpu-hotplug-spec (renamed from Documentation/x86_64/cpu-hotplug-spec)0
-rw-r--r--Documentation/x86/x86_64/fake-numa-for-cpusets (renamed from Documentation/x86_64/fake-numa-for-cpusets)0
-rw-r--r--Documentation/x86/x86_64/kernel-stacks (renamed from Documentation/x86_64/kernel-stacks)0
-rw-r--r--Documentation/x86/x86_64/machinecheck (renamed from Documentation/x86_64/machinecheck)0
-rw-r--r--Documentation/x86/x86_64/mm.txt (renamed from Documentation/x86_64/mm.txt)5
-rw-r--r--Documentation/x86/x86_64/uefi.txt (renamed from Documentation/x86_64/uefi.txt)4
16 files changed, 168 insertions, 46 deletions
diff --git a/Documentation/ABI/testing/sysfs-firmware-memmap b/Documentation/ABI/testing/sysfs-firmware-memmap
new file mode 100644
index 000000000000..0d99ee6ae02e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-firmware-memmap
@@ -0,0 +1,71 @@
1What: /sys/firmware/memmap/
2Date: June 2008
3Contact: Bernhard Walle <bwalle@suse.de>
4Description:
5 On all platforms, the firmware provides a memory map which the
6 kernel reads. The resources from that memory map are registered
7 in the kernel resource tree and exposed to userspace via
8 /proc/iomem (together with other resources).
9
10 However, on most architectures that firmware-provided memory
11 map is modified afterwards by the kernel itself, either because
12 the kernel merges that memory map with other information or
13 just because the user overwrites that memory map via command
14 line.
15
16 kexec needs the raw firmware-provided memory map to setup the
17 parameter segment of the kernel that should be booted with
18 kexec. Also, the raw memory map is useful for debugging. For
19 that reason, /sys/firmware/memmap is an interface that provides
20 the raw memory map to userspace.
21
22 The structure is as follows: Under /sys/firmware/memmap there
23 are subdirectories with the number of the entry as their name:
24
25 /sys/firmware/memmap/0
26 /sys/firmware/memmap/1
27 /sys/firmware/memmap/2
28 /sys/firmware/memmap/3
29 ...
30
31 The maximum depends on the number of memory map entries provided
32 by the firmware. The order is just the order that the firmware
33 provides.
34
35 Each directory contains three files:
36
37 start : The start address (as hexadecimal number with the
38 '0x' prefix).
39 end : The end address, inclusive (regardless whether the
40 firmware provides inclusive or exclusive ranges).
41 type : Type of the entry as string. See below for a list of
42 valid types.
43
44 So, for example:
45
46 /sys/firmware/memmap/0/start
47 /sys/firmware/memmap/0/end
48 /sys/firmware/memmap/0/type
49 /sys/firmware/memmap/1/start
50 ...
51
52 Currently following types exist:
53
54 - System RAM
55 - ACPI Tables
56 - ACPI Non-volatile Storage
57 - reserved
58
59 Following shell snippet can be used to display that memory
60 map in a human-readable format:
61
62 -------------------- 8< ----------------------------------------
63 #!/bin/bash
64 cd /sys/firmware/memmap
65 for dir in * ; do
66 start=$(cat $dir/start)
67 end=$(cat $dir/end)
68 type=$(cat $dir/type)
69 printf "%016x-%016x (%s)\n" $start $[ $end +1] "$type"
70 done
71 -------------------- >8 ----------------------------------------
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index b8e52c0355d3..9691c7f5166c 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -109,7 +109,7 @@ There are two possible methods of using Kdump.
1092) Or use the system kernel binary itself as dump-capture kernel and there is 1092) Or use the system kernel binary itself as dump-capture kernel and there is
110 no need to build a separate dump-capture kernel. This is possible 110 no need to build a separate dump-capture kernel. This is possible
111 only with the architecutres which support a relocatable kernel. As 111 only with the architecutres which support a relocatable kernel. As
112 of today i386 and ia64 architectures support relocatable kernel. 112 of today, i386, x86_64 and ia64 architectures support relocatable kernel.
113 113
114Building a relocatable kernel is advantageous from the point of view that 114Building a relocatable kernel is advantageous from the point of view that
115one does not have to build a second kernel for capturing the dump. But 115one does not have to build a second kernel for capturing the dump. But
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b52f47d588b4..795c487af8e4 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -271,6 +271,17 @@ and is between 256 and 4096 characters. It is defined in the file
271 aic79xx= [HW,SCSI] 271 aic79xx= [HW,SCSI]
272 See Documentation/scsi/aic79xx.txt. 272 See Documentation/scsi/aic79xx.txt.
273 273
274 amd_iommu= [HW,X86-84]
275 Pass parameters to the AMD IOMMU driver in the system.
276 Possible values are:
277 isolate - enable device isolation (each device, as far
278 as possible, will get its own protection
279 domain)
280 amd_iommu_size= [HW,X86-64]
281 Define the size of the aperture for the AMD IOMMU
282 driver. Possible values are:
283 '32M', '64M' (default), '128M', '256M', '512M', '1G'
284
274 amijoy.map= [HW,JOY] Amiga joystick support 285 amijoy.map= [HW,JOY] Amiga joystick support
275 Map of devices attached to JOY0DAT and JOY1DAT 286 Map of devices attached to JOY0DAT and JOY1DAT
276 Format: <a>,<b> 287 Format: <a>,<b>
@@ -599,6 +610,29 @@ and is between 256 and 4096 characters. It is defined in the file
599 See drivers/char/README.epca and 610 See drivers/char/README.epca and
600 Documentation/digiepca.txt. 611 Documentation/digiepca.txt.
601 612
613 disable_mtrr_cleanup [X86]
614 enable_mtrr_cleanup [X86]
615 The kernel tries to adjust MTRR layout from continuous
616 to discrete, to make X server driver able to add WB
617 entry later. This parameter enables/disables that.
618
619 mtrr_chunk_size=nn[KMG] [X86]
620 used for mtrr cleanup. It is largest continous chunk
621 that could hold holes aka. UC entries.
622
623 mtrr_gran_size=nn[KMG] [X86]
624 Used for mtrr cleanup. It is granularity of mtrr block.
625 Default is 1.
626 Large value could prevent small alignment from
627 using up MTRRs.
628
629 mtrr_spare_reg_nr=n [X86]
630 Format: <integer>
631 Range: 0,7 : spare reg number
632 Default : 1
633 Used for mtrr cleanup. It is spare mtrr entries number.
634 Set to 2 or more if your graphical card needs more.
635
602 disable_mtrr_trim [X86, Intel and AMD only] 636 disable_mtrr_trim [X86, Intel and AMD only]
603 By default the kernel will trim any uncacheable 637 By default the kernel will trim any uncacheable
604 memory out of your available memory pool based on 638 memory out of your available memory pool based on
@@ -2116,6 +2150,9 @@ and is between 256 and 4096 characters. It is defined in the file
2116 usbhid.mousepoll= 2150 usbhid.mousepoll=
2117 [USBHID] The interval which mice are to be polled at. 2151 [USBHID] The interval which mice are to be polled at.
2118 2152
2153 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2154 kernel's map of available physical RAM.
2155
2119 vdso= [X86-32,SH,x86-64] 2156 vdso= [X86-32,SH,x86-64]
2120 vdso=2: enable compat VDSO (default with COMPAT_VDSO) 2157 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2121 vdso=1: enable VDSO (default) 2158 vdso=1: enable VDSO (default)
diff --git a/Documentation/nmi_watchdog.txt b/Documentation/nmi_watchdog.txt
index 757c729ee42e..90aa4531cb67 100644
--- a/Documentation/nmi_watchdog.txt
+++ b/Documentation/nmi_watchdog.txt
@@ -10,7 +10,7 @@ us to generate 'watchdog NMI interrupts'. (NMI: Non Maskable Interrupt
10which get executed even if the system is otherwise locked up hard). 10which get executed even if the system is otherwise locked up hard).
11This can be used to debug hard kernel lockups. By executing periodic 11This can be used to debug hard kernel lockups. By executing periodic
12NMI interrupts, the kernel can monitor whether any CPU has locked up, 12NMI interrupts, the kernel can monitor whether any CPU has locked up,
13and print out debugging messages if so. 13and print out debugging messages if so.
14 14
15In order to use the NMI watchdog, you need to have APIC support in your 15In order to use the NMI watchdog, you need to have APIC support in your
16kernel. For SMP kernels, APIC support gets compiled in automatically. For 16kernel. For SMP kernels, APIC support gets compiled in automatically. For
@@ -22,8 +22,7 @@ CONFIG_X86_UP_IOAPIC is for uniprocessor with an IO-APIC. [Note: certain
22kernel debugging options, such as Kernel Stack Meter or Kernel Tracer, 22kernel debugging options, such as Kernel Stack Meter or Kernel Tracer,
23may implicitly disable the NMI watchdog.] 23may implicitly disable the NMI watchdog.]
24 24
25For x86-64, the needed APIC is always compiled in, and the NMI watchdog is 25For x86-64, the needed APIC is always compiled in.
26always enabled with I/O-APIC mode (nmi_watchdog=1).
27 26
28Using local APIC (nmi_watchdog=2) needs the first performance register, so 27Using local APIC (nmi_watchdog=2) needs the first performance register, so
29you can't use it for other purposes (such as high precision performance 28you can't use it for other purposes (such as high precision performance
@@ -63,16 +62,15 @@ when the system is idle), but if your system locks up on anything but the
63"hlt", then you are out of luck -- the event will not happen at all and the 62"hlt", then you are out of luck -- the event will not happen at all and the
64watchdog won't trigger. This is a shortcoming of the local APIC watchdog 63watchdog won't trigger. This is a shortcoming of the local APIC watchdog
65-- unfortunately there is no "clock ticks" event that would work all the 64-- unfortunately there is no "clock ticks" event that would work all the
66time. The I/O APIC watchdog is driven externally and has no such shortcoming. 65time. The I/O APIC watchdog is driven externally and has no such shortcoming.
67But its NMI frequency is much higher, resulting in a more significant hit 66But its NMI frequency is much higher, resulting in a more significant hit
68to the overall system performance. 67to the overall system performance.
69 68
70NOTE: starting with 2.4.2-ac18 the NMI-oopser is disabled by default, 69On x86 nmi_watchdog is disabled by default so you have to enable it with
71you have to enable it with a boot time parameter. Prior to 2.4.2-ac18 70a boot time parameter.
72the NMI-oopser is enabled unconditionally on x86 SMP boxes.
73 71
74On x86-64 the NMI oopser is on by default. On 64bit Intel CPUs 72NOTE: In kernels prior to 2.4.2-ac18 the NMI-oopser is enabled unconditionally
75it uses IO-APIC by default and on AMD it uses local APIC. 73on x86 SMP boxes.
76 74
77[ feel free to send bug reports, suggestions and patches to 75[ feel free to send bug reports, suggestions and patches to
78 Ingo Molnar <mingo@redhat.com> or the Linux SMP mailing 76 Ingo Molnar <mingo@redhat.com> or the Linux SMP mailing
diff --git a/Documentation/i386/IO-APIC.txt b/Documentation/x86/i386/IO-APIC.txt
index 30b4c714fbe1..30b4c714fbe1 100644
--- a/Documentation/i386/IO-APIC.txt
+++ b/Documentation/x86/i386/IO-APIC.txt
diff --git a/Documentation/i386/boot.txt b/Documentation/x86/i386/boot.txt
index 95ad15c3b01f..147bfe511cdd 100644
--- a/Documentation/i386/boot.txt
+++ b/Documentation/x86/i386/boot.txt
@@ -1,17 +1,14 @@
1 THE LINUX/I386 BOOT PROTOCOL 1 THE LINUX/x86 BOOT PROTOCOL
2 ---------------------------- 2 ---------------------------
3 3
4 H. Peter Anvin <hpa@zytor.com> 4On the x86 platform, the Linux kernel uses a rather complicated boot
5 Last update 2007-05-23
6
7On the i386 platform, the Linux kernel uses a rather complicated boot
8convention. This has evolved partially due to historical aspects, as 5convention. This has evolved partially due to historical aspects, as
9well as the desire in the early days to have the kernel itself be a 6well as the desire in the early days to have the kernel itself be a
10bootable image, the complicated PC memory model and due to changed 7bootable image, the complicated PC memory model and due to changed
11expectations in the PC industry caused by the effective demise of 8expectations in the PC industry caused by the effective demise of
12real-mode DOS as a mainstream operating system. 9real-mode DOS as a mainstream operating system.
13 10
14Currently, the following versions of the Linux/i386 boot protocol exist. 11Currently, the following versions of the Linux/x86 boot protocol exist.
15 12
16Old kernels: zImage/Image support only. Some very early kernels 13Old kernels: zImage/Image support only. Some very early kernels
17 may not even support a command line. 14 may not even support a command line.
@@ -372,10 +369,17 @@ Protocol: 2.00+
372 - If 0, the protected-mode code is loaded at 0x10000. 369 - If 0, the protected-mode code is loaded at 0x10000.
373 - If 1, the protected-mode code is loaded at 0x100000. 370 - If 1, the protected-mode code is loaded at 0x100000.
374 371
372 Bit 5 (write): QUIET_FLAG
373 - If 0, print early messages.
374 - If 1, suppress early messages.
375 This requests to the kernel (decompressor and early
376 kernel) to not write early messages that require
377 accessing the display hardware directly.
378
375 Bit 6 (write): KEEP_SEGMENTS 379 Bit 6 (write): KEEP_SEGMENTS
376 Protocol: 2.07+ 380 Protocol: 2.07+
377 - if 0, reload the segment registers in the 32bit entry point. 381 - If 0, reload the segment registers in the 32bit entry point.
378 - if 1, do not reload the segment registers in the 32bit entry point. 382 - If 1, do not reload the segment registers in the 32bit entry point.
379 Assume that %cs %ds %ss %es are all set to flat segments with 383 Assume that %cs %ds %ss %es are all set to flat segments with
380 a base of 0 (or the equivalent for their environment). 384 a base of 0 (or the equivalent for their environment).
381 385
@@ -504,7 +508,7 @@ Protocol: 2.06+
504 maximum size was 255. 508 maximum size was 255.
505 509
506Field name: hardware_subarch 510Field name: hardware_subarch
507Type: write 511Type: write (optional, defaults to x86/PC)
508Offset/size: 0x23c/4 512Offset/size: 0x23c/4
509Protocol: 2.07+ 513Protocol: 2.07+
510 514
@@ -520,11 +524,13 @@ Protocol: 2.07+
520 0x00000002 Xen 524 0x00000002 Xen
521 525
522Field name: hardware_subarch_data 526Field name: hardware_subarch_data
523Type: write 527Type: write (subarch-dependent)
524Offset/size: 0x240/8 528Offset/size: 0x240/8
525Protocol: 2.07+ 529Protocol: 2.07+
526 530
527 A pointer to data that is specific to hardware subarch 531 A pointer to data that is specific to hardware subarch
532 This field is currently unused for the default x86/PC environment,
533 do not modify.
528 534
529Field name: payload_offset 535Field name: payload_offset
530Type: read 536Type: read
@@ -545,6 +551,34 @@ Protocol: 2.08+
545 551
546 The length of the payload. 552 The length of the payload.
547 553
554Field name: setup_data
555Type: write (special)
556Offset/size: 0x250/8
557Protocol: 2.09+
558
559 The 64-bit physical pointer to NULL terminated single linked list of
560 struct setup_data. This is used to define a more extensible boot
561 parameters passing mechanism. The definition of struct setup_data is
562 as follow:
563
564 struct setup_data {
565 u64 next;
566 u32 type;
567 u32 len;
568 u8 data[0];
569 };
570
571 Where, the next is a 64-bit physical pointer to the next node of
572 linked list, the next field of the last node is 0; the type is used
573 to identify the contents of data; the len is the length of data
574 field; the data holds the real payload.
575
576 This list may be modified at a number of points during the bootup
577 process. Therefore, when modifying this list one should always make
578 sure to consider the case where the linked list already contains
579 entries.
580
581
548**** THE IMAGE CHECKSUM 582**** THE IMAGE CHECKSUM
549 583
550From boot protocol version 2.08 onwards the CRC-32 is calculated over 584From boot protocol version 2.08 onwards the CRC-32 is calculated over
@@ -553,6 +587,7 @@ initial remainder of 0xffffffff. The checksum is appended to the
553file; therefore the CRC of the file up to the limit specified in the 587file; therefore the CRC of the file up to the limit specified in the
554syssize field of the header is always 0. 588syssize field of the header is always 0.
555 589
590
556**** THE KERNEL COMMAND LINE 591**** THE KERNEL COMMAND LINE
557 592
558The kernel command line has become an important way for the boot 593The kernel command line has become an important way for the boot
@@ -584,28 +619,6 @@ command line is entered using the following protocol:
584 covered by setup_move_size, so you may need to adjust this 619 covered by setup_move_size, so you may need to adjust this
585 field. 620 field.
586 621
587Field name: setup_data
588Type: write (obligatory)
589Offset/size: 0x250/8
590Protocol: 2.09+
591
592 The 64-bit physical pointer to NULL terminated single linked list of
593 struct setup_data. This is used to define a more extensible boot
594 parameters passing mechanism. The definition of struct setup_data is
595 as follow:
596
597 struct setup_data {
598 u64 next;
599 u32 type;
600 u32 len;
601 u8 data[0];
602 };
603
604 Where, the next is a 64-bit physical pointer to the next node of
605 linked list, the next field of the last node is 0; the type is used
606 to identify the contents of data; the len is the length of data
607 field; the data holds the real payload.
608
609 622
610**** MEMORY LAYOUT OF THE REAL-MODE CODE 623**** MEMORY LAYOUT OF THE REAL-MODE CODE
611 624
diff --git a/Documentation/i386/usb-legacy-support.txt b/Documentation/x86/i386/usb-legacy-support.txt
index 1894cdfc69d9..1894cdfc69d9 100644
--- a/Documentation/i386/usb-legacy-support.txt
+++ b/Documentation/x86/i386/usb-legacy-support.txt
diff --git a/Documentation/i386/zero-page.txt b/Documentation/x86/i386/zero-page.txt
index 169ad423a3d1..169ad423a3d1 100644
--- a/Documentation/i386/zero-page.txt
+++ b/Documentation/x86/i386/zero-page.txt
diff --git a/Documentation/x86_64/00-INDEX b/Documentation/x86/x86_64/00-INDEX
index 92fc20ab5f0e..92fc20ab5f0e 100644
--- a/Documentation/x86_64/00-INDEX
+++ b/Documentation/x86/x86_64/00-INDEX
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index b0c7b6c4abda..b0c7b6c4abda 100644
--- a/Documentation/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
diff --git a/Documentation/x86_64/cpu-hotplug-spec b/Documentation/x86/x86_64/cpu-hotplug-spec
index 3c23e0587db3..3c23e0587db3 100644
--- a/Documentation/x86_64/cpu-hotplug-spec
+++ b/Documentation/x86/x86_64/cpu-hotplug-spec
diff --git a/Documentation/x86_64/fake-numa-for-cpusets b/Documentation/x86/x86_64/fake-numa-for-cpusets
index d1a985c5b00a..d1a985c5b00a 100644
--- a/Documentation/x86_64/fake-numa-for-cpusets
+++ b/Documentation/x86/x86_64/fake-numa-for-cpusets
diff --git a/Documentation/x86_64/kernel-stacks b/Documentation/x86/x86_64/kernel-stacks
index 5ad65d51fb95..5ad65d51fb95 100644
--- a/Documentation/x86_64/kernel-stacks
+++ b/Documentation/x86/x86_64/kernel-stacks
diff --git a/Documentation/x86_64/machinecheck b/Documentation/x86/x86_64/machinecheck
index a05e58e7b159..a05e58e7b159 100644
--- a/Documentation/x86_64/machinecheck
+++ b/Documentation/x86/x86_64/machinecheck
diff --git a/Documentation/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index b89b6d2bebfa..efce75097369 100644
--- a/Documentation/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -11,9 +11,8 @@ ffffc10000000000 - ffffc1ffffffffff (=40 bits) hole
11ffffc20000000000 - ffffe1ffffffffff (=45 bits) vmalloc/ioremap space 11ffffc20000000000 - ffffe1ffffffffff (=45 bits) vmalloc/ioremap space
12ffffe20000000000 - ffffe2ffffffffff (=40 bits) virtual memory map (1TB) 12ffffe20000000000 - ffffe2ffffffffff (=40 bits) virtual memory map (1TB)
13... unused hole ... 13... unused hole ...
14ffffffff80000000 - ffffffff82800000 (=40 MB) kernel text mapping, from phys 0 14ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0
15... unused hole ... 15ffffffffa0000000 - fffffffffff00000 (=1536 MB) module mapping space
16ffffffff88000000 - fffffffffff00000 (=1919 MB) module mapping space
17 16
18The direct mapping covers all memory in the system up to the highest 17The direct mapping covers all memory in the system up to the highest
19memory address (this means in some cases it can also include PCI memory 18memory address (this means in some cases it can also include PCI memory
diff --git a/Documentation/x86_64/uefi.txt b/Documentation/x86/x86_64/uefi.txt
index 7d77120a5184..a5e2b4fdb170 100644
--- a/Documentation/x86_64/uefi.txt
+++ b/Documentation/x86/x86_64/uefi.txt
@@ -36,3 +36,7 @@ Mechanics:
36 services. 36 services.
37 noefi turn off all EFI runtime services 37 noefi turn off all EFI runtime services
38 reboot_type=k turn off EFI reboot runtime service 38 reboot_type=k turn off EFI reboot runtime service
39- If the EFI memory map has additional entries not in the E820 map,
40 you can include those entries in the kernels memory map of available
41 physical RAM by using the following kernel command line parameter.
42 add_efi_memmap include EFI memory map of available physical RAM