How-To: See Which CPU Microcode Your Linux Box Is Actually Running

Microcode updates are easy to miss, because the package can update while the CPU keeps running the old revision until you reboot. Here’s how I check on my Omarchy laptop and my servers.

1. The revision the CPU is running right now

grep -m1 microcode /proc/cpuinfo

2. Did it load at boot, and from where?

journalctl -k -b | grep -i microcode

You want a line saying the microcode was updated early, along with the revision.

3. Which package version is installed

# Arch / Omarchy
pacman -Q intel-ucode amd-ucode 2>/dev/null
# Debian / Ubuntu
dpkg -l | grep -E 'intel-microcode|amd64-microcode'

4. Update, then reboot

Update the normal way. On Arch-based systems the initramfs picks up the microcode through the microcode hook in /etc/mkinitcpio.conf. Then reboot and run step 1 again. If the revision didn’t change, either your CPU isn’t covered by this release or the early load isn’t set up.

5. Across the fleet

ansible all -m shell -a "grep -m1 microcode /proc/cpuinfo"

I keep the output and diff it after each update cycle so I can see which boxes still need a reboot.

God Bless, and Happy hacking!

References & Further Reading

• Microcode (ArchWiki)
• Intel releases new CPU microcode (Phoronix)