microcode_ctl(8) microcode utility for Intel IA32 processors


microcode_ctl [-h] [-u] [-q] [-Q] [-f microcode]


The microcode_ctl utility is a companion to the IA32 microcode driver written by Tigran Aivazian <[email protected]>. The utility has two uses:

a) it decodes and sends new microcode to the kernel driver to be uploaded to Intel IA32 processors. (Pentium Pro, PII, Celeron, PIII, Xeon, Pentium 4 etc)

b) it signals the kernel driver to release the buffers containing the copy of microcode data actually applied to given CPU, linear array of 2048 bytes per CPU, see struct microcode in include/asm/processor.h for information on the layout of chunks buffers may hold

The microcode update is volatile and needs to be uploaded on each system boot i.e. it doesn't reflash your cpu permanently, reboot and it reverts back to the old microcode.

display usage and exit
upload microcode (from default filename)
upload microcode from named Intel formatted file
run silently when successful
run silently even on failure


microcode_ctl -u
Upload microcode using defaults


The default microcode location


Microcode utility written by Simon Trimmer
Linux Kernel driver written by Tigran Aivazian.


Report bugs to either Simon Trimmer <[email protected]> or Tigran Aivazian <[email protected]>


Copyright © 2000 VERITAS Software
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


Thanks to the Intel Corporation, for supplying microcode update data and publishing the specifications that enabled us to write microcode driver for Linux.