Odi's astoundingly incomplete notes

Gentoo intel-microcode reorg

Gentoo has given more love to its sys-firmware/intel-microcode package. It's now easier than ever to update microcode automatically early on boot. This is a valuable alternative to shipping microcode within the BIOS. I mean honestly, who regularly checks for BIOS updates? Much easier by doing that through an ebuild.

The new USE flag initramfs now builds a cpio archive at /boot/intel-uc.img ready to be used by grub. In /boot/grub/grub.cfg:

menuentry 'Gentoo Linux 4.14' {
  root=hd0,1
  linux /boot/linux-4.14.12 root=LABEL=ROOT ro rootfstype=ext4 net.ifnames=0
  initrd /boot/intel-uc.img /boot/initrd.img
}

Note how the microcode intitramfs is simply prepended to the boot initramfs (initrd). A kernel that has microcode laoding support enabled will find it there, upload the microcode into the cpu and then discard the initramfs blob, and continue booting with the initrd.img. The first line in your dmesg output will show:

microcode: microcode updated early to revision 0x80, date = 2018-01-04

posted on 2018-01-15 10:10 UTC in Code | 0 comments | permalink

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