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This article describes updating the microcode for AMD processors. In most cases the firmware of a system, i.e. the BIOS or UEFI, will contain updated processor microcode. It is recommended to always update the system firmware, because vendors will also incorporate new microcode provided by AMD with their BIOS updates (in the changelog this is often called "AGESA update"). It is however also possible to have the Linux kernel load the same updated microcode.
For the Linux kernel to support CPU microcode loading, the following must be enabled if a kernel lower than version 6.6 is used. With kernel version 6.6 this is automatically activated and can no longer be selected [1] [2]:
Processor type and features ---> [*] CPU microcode loading support [ ] Intel microcode loading support [*] AMD microcode loading support
For the kernel to be able to load any firmware (including microcode), the firmware loading facility option must also be enabled:
Device Drivers --->
Generic Driver Options
Firmware loader --->
{*} Firmware loading facility
When microcode is available and the kernel is configured, it will update microcode automatically. In most modern configurations the root partition (where the /lib/firmware directory is located) will be mounted during the boot process. For this reason, to be able to update the microcode as soon as possible, it is also necessary to include the microcode firmware blobs either in the kernel image or the initrd/initramfs.
{M} Firmware loading facility i.e. CONFIG_FW_LOADER=M, will prevent early microcode updating in most setups.For further instructions, refer to the Microcode article.
Microcode updates for AMD processors are provided by the sys-kernel/linux-firmware package.
root #emerge --ask sys-kernel/linux-firmwareThere are different firmware files for different AMD CPU families. The CPU family identification of the current system can be obtained from /proc/cpuinfo:
user $grep -F -m 1 "cpu family" /proc/cpuinfocpu family : 22
In this example the CPU belongs to the AMD CPU family 22.
The following table helps to identify the right firmware blob file for a given CPU family identificator:
| Firmware blob file | Decimal | Hexadecimal | Family name | Year | Examples |
|---|---|---|---|---|---|
| amd-ucode/microcode_amd.bin | 16 | 10h
|
K10 | 2007 | Phenom, Phenom II, Athlon II |
| 17 | 11h
|
Turion | 2008 | Athlon X2, Sempron X2, Turion X2 | |
| 18 | 12h
|
Llano, Fusion | 2009 | A- and E2-Series APU with Radeon HD graphics, Athlon II, Sempron X2 | |
| 20 | 14h
|
Bobcat | 2011 | C- and E-Series APU with Radeon HD graphics | |
| amd-ucode/microcode_amd_fam15h.bin | 21 | 15h
|
Bulldozer, Piledriver, Steamroller, Excavator | 2011 | FX series, A-Series APU with Radeon HD graphics, Opteron 6200/6300 |
| amd-ucode/microcode_amd_fam16h.bin | 22 | 16h
|
Jaguar, Puma | 2013 | A-series and E-Series APU with Radeon HD graphics |
| amd-ucode/microcode_amd_fam17h.bin | 23 | 17h
|
Zen, Zen+, Zen 2 | 2017 | Ryzen 1000-5000 series, Threadripper, EPYC 7xx1/7xx2 |
| amd/amd_sev_fam17h_model0xh.sbin | EPYC 7xx1[3] (Zen 1) | 2017 | SEV (Secure Encrypted Virtualization) firmware update for models in the range 00h to 0fh[4]
| ||
| amd/amd_sev_fam17h_model3xh.sbin | EPYC 7xx2[5] (Zen 2) | 2019 | SEV firmware update for models in the range 30h to 3fh[6]
| ||
| amd-ucode/microcode_amd_fam19h.bin | 25 | 19h
|
Zen 3 and Zen 4 | 2021 | Ryzen 5000 series (not all models), Ryzen 9 7900X & 7950X series, EPYC 7xx3 |
| amd/amd_sev_fam19h_model0xh.sbin | EPYC 7xx3[7] (Zen 3) | 2021 | SEV firmware update for models in the range 00h to 0fh[8]
| ||
| amd/amd_sev_fam1ah_model0xh.sbin | 26 | 1ah
|
EPYC 9005[9] (Zen 5) | 2025 | SEV firmware update for models in the range 00h to 0fh[10]
|
0F hexadecimal or 15 decimal).It is possible to incorporate the microcode firmware blob files for all AMD processors in the Linux kernel, but it should be considered that this will enlarge the kernel image by the combined size of those files.
Device Drivers --->
Generic Driver Options
Firmware loader --->
{*} Firmware loading facility
(amd-ucode/microcode_amd.bin amd-ucode/microcode_amd_fam15h.bin amd-ucode/microcode_amd_fam16h.bin amd-ucode/microcode_amd_fam17h.bin amd/amd_sev_fam17h_model0xh.sbin amd/amd_sev_fam17h_model3xh.sbin amd-ucode/microcode_amd_fam19h.bin amd/amd_sev_fam19h_model0xh.sbin) External firmware blobs to build into the kernel binary
(/lib/firmware) Firmware blobs root directory
For in-kernel microcode it may be preferable to only include the firmware blob file(s) specific to the identified CPU. For example, for the EPYC 7xx1 CPU family this would be CONFIG_EXTRA_FIRMWARE="amd-ucode/microcode_amd_fam17h.bin amd/amd_sev_fam17h_model0xh.sbin".
Instead of in-kernel, the firmware blob files can also be included in an (additional) initrd/initramfs.
General setup --- > [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support (BLK_DEV_INITRD)
This method has the advantage that only the specific initrd/initramfs must be rebuild in case of a firmware files update. If the initramfs USE flag is used with the sys-kernel/linux-firmware package, microcode for all AMD processors will be saved in /boot/amd-uc.img, allowing it to be loaded alongside any other initrd/initramfs by a Linux bootloader such as GRUB.
initramfs USE flag set, package sys-kernel/linux-firmware will fail if /boot is a separate partition and is not mounted before installing or updating the package (by running emerge).Booting a capable kernel, the following line should be observed in case a microcode update was performed: microcode: updated early
In any case the output will show a patch_level. The following example shows a successful early microcode update using the Linux kernel and supplied microcode firmware blob files (in-kernel or from an initrd/initramfs):
user $dmesg | grep microcode[ 0.584603] microcode: microcode: updated early to new patch_level=0x06000832 [ 0.868036] microcode: CPU0: patch_level=0x06000832 [ 0.868116] microcode: CPU1: patch_level=0x06000832 [ 0.868196] microcode: CPU2: patch_level=0x06000832 [ 0.868277] microcode: CPU3: patch_level=0x06000832 [ 0.868360] microcode: CPU4: patch_level=0x06000832 [ 0.868451] microcode: CPU5: patch_level=0x06000832 [ 0.868538] microcode: CPU6: patch_level=0x06000832 [ 0.868619] microcode: CPU7: patch_level=0x06000832 [ 0.868718] microcode: Microcode Update Driver: v2.01 <tigran@aivazian.fsnet.co.uk>, Peter Oruba
The image file /boot/amd-uc.img is in a file path recognized by GRUB by default, but only after regenerating the grub configuration. This is done by the following command:
root #grub-mkconfig -o /boot/grub/grub.cfgFound linux image: /boot/vmlinuz-4.18.12 Found initrd image: /boot/amd-uc.img /boot/initramfs-4.18.12.img
The command output should show it found the /boot/amd-uc.img file.
After updating sys-kernel/linux-firmware that includes updated AMD processor microcode they will only be installed to /lib/firmware on the root directory. With the initramfs USE flag set the package will also update /boot/amd-uc.img with the new firmware files, whereas (if so configured) both the main initramfs/initrd as well as the kernel will still contain the previous files from sys-kernel/linux-firmware.
If the microcode was supplied in-kernel, rebuilding and installing the kernel as usual is needed to finally provide the new microcode firmware files to the kernel during the boot process. Likewise, if the microcode was included in the main initramfs/initrd, rebuilding it will be necessary to replace the previous with the new versions of the microcode firmware files.
If the patch-level still doesn't change after including the updated firmware files it is very likely that the microcode simply doesn't apply for the specific CPU.