Intel Processor Microcode Package for Linux | |
CPU microcode is a mechanism to correct certain errata in existing systems. | |
The normal preferred method to apply microcode updates is using the system | |
BIOS, but for a subset of Intel's processors this can be done at runtime | |
using the operating system. This package contains those processors that | |
support OS loading of microcode updates. | |
The target user for this package are OS vendors such as Linux distributions | |
for inclusion in their OS releases. Intel recommends getting the microcode | |
using the OS vendor update mechanism. Expert users can of course update their | |
microcode directly outside the OS vendor mechanism. This method is complex and | |
thus could be error prone. | |
Microcode is best loaded from the BIOS. Certain microcode must only be applied | |
from the BIOS. Such processor microcode updates are never packaged in this | |
package since they are not appropriate for OS distribution. An OEM may receive | |
microcode packages that might be a superset of what is contained in this | |
package. | |
OS vendors may choose to also update microcode that kernel can consume for early | |
loading. For e.g. Linux can update processor microcode very early in the kernel | |
boot sequence. In situations when the BIOS update isn't available, early loading | |
is the next best alternative to updating processor microcode. Microcode states | |
are reset on a power reset, hence its required to be updated everytime during | |
boot process. | |
Loading microcode using the initrd method is recommended so that the microcode | |
is loaded at the earliest time for best coverage. Systems that cannot tolerate | |
downtime may use the late reload method to update a running system without a | |
reboot. | |
== About Processor Signature, Family, Model, Stepping and Platform ID == | |
Processor signature is a number identifying the model and version of a | |
Intel processor. It can be obtained using the CPUID instruction, and can | |
also be obtained via the command lscpu or from the content of /proc/cpuinfo. | |
It's usually presented as 3 fields: Family, Model and Stepping | |
(In the table of updates below, they are shorten as F, MO and S). | |
The width of Family/Model/Stepping is 12/8/4bit, but when arranged in the | |
32bit processor signature raw data is like 0FFM0FMS, hexadecimal. | |
e.g. if a processor signature is 0x000906eb, it means | |
Family=0x006, Model=0x9e and Stepping=0xb | |
A processor product can be implemented for multiple types of platforms, | |
So in MSR(17H), Intel processors have a 3bit Platform ID field, | |
that can specify a platform type from at most 8 types. | |
A microcode file for a specified processor model can support multiple | |
platforms, so the Platform ID of a microcode (shorten as PI in the table) | |
is a 8bit mask, each set bit indicates a platform type that it supports. | |
One can find the platform ID on Linux using rdmsr from msr-tools. | |
== Microcode update instructions == | |
-- intel-ucode/ -- | |
intel-ucode directory contains binary microcode files named in | |
family-model-stepping pattern. The file is supported in most modern Linux | |
distributions. It's generally located in the /lib/firmware directory, | |
and can be updated through the microcode reload interface. | |
To update early loading initrd, consult your distribution on how to package | |
microcode files for early loading. Some distros use update-initramfs or dracut. | |
As recommended above, please use the OS vendors are recommended method to ensure | |
microcode file is updated for early loading before attempting the late-load | |
procedure below. | |
To update the intel-ucode package to the system, one need: | |
1. Ensure the existence of /sys/devices/system/cpu/microcode/reload | |
2. Copy intel-ucode directory to /lib/firmware, overwrite the files in | |
/lib/firmware/intel-ucode/ | |
3. Write the reload interface to 1 to reload the microcode files, e.g. | |
echo 1 > /sys/devices/system/cpu/microcode/reload | |
If you are using the OS vendor method to update microcode, the above steps may | |
have been done automatically during the update process. | |
-- intel-ucode-with-caveats/ -- | |
This directory holds microcode that might need special handling. | |
BDX-ML microcode is provided in directory, because it need special commits in | |
the Linux kernel, otherwise, updating it might result in unexpected system | |
behavior. | |
OS vendors must ensure that the late loader patches (provided in | |
linux-kernel-patches\) are included in the distribution before packaging the | |
BDX-ML microcode for late-loading. | |
== 20190618 Release == | |
-- Updates upon 20190514 release -- | |
Processor Identifier Version Products | |
Model Stepping F-MO-S/PI Old->New | |
---- new platforms ---------------------------------------- | |
---- updated platforms ------------------------------------ | |
SNB-E/EN/EP C1/M0 6-2d-6/6d 0000061d->0000061f Xeon E3/E5, Core X | |
SNB-E/EN/EP C2/M1 6-2d-7/6d 00000714->00000718 Xeon E3/E5, Core X |