CPU microcode

On specific CPUs, you have CPU microcode, which can be updated through regular packages.

For Intel CPUs:

# apk add ucode-intel


# apk add ucode-amd

In most cases, you want early microcode loading via initramfs, which Chimera can do by default. You just have to refresh them:

# update-initramfs -c -k all

This will result in microcode being included in the initramfs. On Intel CPUs, only the microcode necessary for the current machine is included by default. You can tweak the configuration of both via their respective files in /etc/default. You can also disable initramfs inclusion if you wish to do something else.

For subsequent kernel updates, you will no longer have to manually refresh your initramfs, it will be done automatically.

Microcode loading via bootloader

If you’d like to instead load your microcode through the bootloader without using initramfs (e.g. if you have no initramfs or if you have some other reason), you can use full cpio images.

For Intel CPUs:

# apk add ucode-intel-full


# apk add ucode-amd-full

You can then tweak your bootloader configuration accordingly. Make sure not to forget to disable the initramfs hooks if you are using one. Alternatively, you can remove the regular ucode packages, as the -full packages do not depend on them.