microcode.txt

Loading and checking processor microcode

BITS can load processor microcode for you, or check your current microcode
version and compare it to available microcodes.  You can find these options
under the Configure menu.

To check your current microcode version, you can run mcu_status with no
arguments.

To load microcode, or compare your current microcode version to available
microcodes, you need a microcode data file.  You can get one from
https://downloadcenter.intel.com/ , under "Processors".  You can then run
mcu_status with that file to check for a newer microcode, or run mcu_load
with that file to load it.

mcu_status and mcu_load can also take one or more directories as well as
files; given a directory, they will attempt to load *every* file in the
directory as a microcode database.  (They will not recurse into
subdirectories, however.)  The menu options for checking and loading
microcode default to checking /boot/mcu.first and /boot/mcu, in that order.
If you download a microcode data file, you can put it in /boot/mcu and the
menu options will find it.  /boot/mcu.first exists in case you have a
processor-specific microcode you want to load instead of one from the full
standard microcode database.

mcu_status and mcu_load support both binary microcode files and text-based
microcode files.  Note, though, that any file other than a microcode database
will probably get parsed as one anyway, with unhelpful (though not dangerous)
results; in particular, don't give mcu_status or mcu_load a directory
containing any files other than a microcode database.