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Documentation: x86: convert microcode.txt to reST 

This converts the plain text documentation to reStructuredText format and
add it to Sphinx TOC tree. No essential content change.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Changbin Du 2019-05-08 23:21:30 +08:00 committed by Jonathan Corbet
parent ea0765e835
commit 3d07bc393f
2 changed files with 35 additions and 28 deletions
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1
Documentation/x86/index.rst
View File

@ -22,3 +22,4 @@ x86-specific Documentation
intel_mpx intel_mpx
amd-memory-encryption amd-memory-encryption
pti pti
microcode

62
Documentation/x86/microcode.txt → Documentation/x86/microcode.rst
View File

@ -1,7 +1,11 @@
The Linux Microcode Loader .. SPDX-License-Identifier: GPL-2.0
Authors: Fenghua Yu <fenghua.yu@intel.com> ==========================
Borislav Petkov <bp@suse.de> The Linux Microcode Loader
==========================
:Authors: - Fenghua Yu <fenghua.yu@intel.com>
- Borislav Petkov <bp@suse.de>
The kernel has a x86 microcode loading facility which is supposed to The kernel has a x86 microcode loading facility which is supposed to
provide microcode loading methods in the OS. Potential use cases are provide microcode loading methods in the OS. Potential use cases are
@ -10,8 +14,8 @@ and updating the microcode on long-running systems without rebooting.
The loader supports three loading methods: The loader supports three loading methods:
1. Early load microcode Early load microcode
======================= ====================
The kernel can update microcode very early during boot. Loading The kernel can update microcode very early during boot. Loading
microcode early can fix CPU issues before they are observed during microcode early can fix CPU issues before they are observed during
@ -26,8 +30,10 @@ loader parses the combined initrd image during boot.
The microcode files in cpio name space are: The microcode files in cpio name space are:
on Intel: kernel/x86/microcode/GenuineIntel.bin on Intel:
on AMD : kernel/x86/microcode/AuthenticAMD.bin kernel/x86/microcode/GenuineIntel.bin
on AMD :
kernel/x86/microcode/AuthenticAMD.bin
During BSP (BootStrapping Processor) boot (pre-SMP), the kernel During BSP (BootStrapping Processor) boot (pre-SMP), the kernel
scans the microcode file in the initrd. If microcode matching the scans the microcode file in the initrd. If microcode matching the
@ -42,8 +48,8 @@ Here's a crude example how to prepare an initrd with microcode (this is
normally done automatically by the distribution, when recreating the normally done automatically by the distribution, when recreating the
initrd, so you don't really have to do it yourself. It is documented initrd, so you don't really have to do it yourself. It is documented
here for future reference only). here for future reference only).
::
---
#!/bin/bash #!/bin/bash
if [ -z "$1" ]; then if [ -z "$1" ]; then
@ -76,15 +82,15 @@ here for future reference only).
cat ucode.cpio $INITRD.orig > $INITRD cat ucode.cpio $INITRD.orig > $INITRD
rm -rf $TMPDIR rm -rf $TMPDIR
---
The system needs to have the microcode packages installed into The system needs to have the microcode packages installed into
/lib/firmware or you need to fixup the paths above if yours are /lib/firmware or you need to fixup the paths above if yours are
somewhere else and/or you've downloaded them directly from the processor somewhere else and/or you've downloaded them directly from the processor
vendor's site. vendor's site.
2. Late loading Late loading
=============== ============
There are two legacy user space interfaces to load microcode, either through There are two legacy user space interfaces to load microcode, either through
/dev/cpu/microcode or through /sys/devices/system/cpu/microcode/reload file /dev/cpu/microcode or through /sys/devices/system/cpu/microcode/reload file
@ -94,9 +100,9 @@ The /dev/cpu/microcode method is deprecated because it needs a special
userspace tool for that. userspace tool for that.
The easier method is simply installing the microcode packages your distro The easier method is simply installing the microcode packages your distro
supplies and running: supplies and running::
# echo 1 > /sys/devices/system/cpu/microcode/reload # echo 1 > /sys/devices/system/cpu/microcode/reload
as root. as root.
@ -104,29 +110,29 @@ The loading mechanism looks for microcode blobs in
/lib/firmware/{intel-ucode,amd-ucode}. The default distro installation /lib/firmware/{intel-ucode,amd-ucode}. The default distro installation
packages already put them there. packages already put them there.
3. Builtin microcode Builtin microcode
==================== =================
The loader supports also loading of a builtin microcode supplied through The loader supports also loading of a builtin microcode supplied through
the regular builtin firmware method CONFIG_EXTRA_FIRMWARE. Only 64-bit is the regular builtin firmware method CONFIG_EXTRA_FIRMWARE. Only 64-bit is
currently supported. currently supported.
Here's an example: Here's an example::
CONFIG_EXTRA_FIRMWARE="intel-ucode/06-3a-09 amd-ucode/microcode_amd_fam15h.bin" CONFIG_EXTRA_FIRMWARE="intel-ucode/06-3a-09 amd-ucode/microcode_amd_fam15h.bin"
CONFIG_EXTRA_FIRMWARE_DIR="/lib/firmware" CONFIG_EXTRA_FIRMWARE_DIR="/lib/firmware"
This basically means, you have the following tree structure locally: This basically means, you have the following tree structure locally::
/lib/firmware/ /lib/firmware/
|-- amd-ucode |-- amd-ucode
... ...
| |-- microcode_amd_fam15h.bin | |-- microcode_amd_fam15h.bin
... ...
|-- intel-ucode |-- intel-ucode
... ...
| |-- 06-3a-09 | |-- 06-3a-09
... ...
so that the build system can find those files and integrate them into so that the build system can find those files and integrate them into
the final kernel image. The early loader finds them and applies them. the final kernel image. The early loader finds them and applies them.