path: root/Documentation/x86
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authorChangbin Du <changbin.du@gmail.com>2019-05-08 15:21:30 (GMT)
committerJonathan Corbet <corbet@lwn.net>2019-05-08 20:34:11 (GMT)
commit3d07bc393f9b63ca4c6f9953922f9122a11f29c3 (patch)
treeed198e1c17f0adbbbb7f7498ad9a1334b39a0765 /Documentation/x86
parentea0765e835e084707abb7e14d84b572f5ffe4242 (diff)
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>
Diffstat (limited to 'Documentation/x86')
-rw-r--r--Documentation/x86/microcode.rst (renamed from Documentation/x86/microcode.txt)62
2 files changed, 35 insertions, 28 deletions
diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
index 6719def..ae29c02 100644
--- a/Documentation/x86/index.rst
+++ b/Documentation/x86/index.rst
@@ -22,3 +22,4 @@ x86-specific Documentation
+ microcode
diff --git a/Documentation/x86/microcode.txt b/Documentation/x86/microcode.rst
index 79fdb4a..a320d37 100644
--- a/Documentation/x86/microcode.txt
+++ b/Documentation/x86/microcode.rst
@@ -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
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:
-1. Early load microcode
+Early load microcode
The kernel can update microcode very early during boot. Loading
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:
-on Intel: kernel/x86/microcode/GenuineIntel.bin
-on AMD : kernel/x86/microcode/AuthenticAMD.bin
+on Intel:
+ kernel/x86/microcode/GenuineIntel.bin
+on AMD :
+ kernel/x86/microcode/AuthenticAMD.bin
During BSP (BootStrapping Processor) boot (pre-SMP), the kernel
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
initrd, so you don't really have to do it yourself. It is documented
here for future reference only).
if [ -z "$1" ]; then
@@ -76,15 +82,15 @@ here for future reference only).
cat ucode.cpio $INITRD.orig > $INITRD
rm -rf $TMPDIR
The system needs to have the microcode packages installed into
/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
vendor's site.
-2. Late loading
+Late loading
There are two legacy user space interfaces to load microcode, either through
/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.
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.
@@ -104,29 +110,29 @@ The loading mechanism looks for microcode blobs in
/lib/firmware/{intel-ucode,amd-ucode}. The default distro installation
packages already put them there.
-3. Builtin microcode
+Builtin microcode
The loader supports also loading of a builtin microcode supplied through
the regular builtin firmware method CONFIG_EXTRA_FIRMWARE. Only 64-bit is
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"
-This basically means, you have the following tree structure locally:
+This basically means, you have the following tree structure locally::
-|-- amd-ucode
-| |-- microcode_amd_fam15h.bin
-|-- intel-ucode
-| |-- 06-3a-09
+ /lib/firmware/
+ |-- amd-ucode
+ ...
+ | |-- microcode_amd_fam15h.bin
+ ...
+ |-- intel-ucode
+ ...
+ | |-- 06-3a-09
+ ...
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.