early x86 microcode loading

[Poul-Henning Kamp]

--------
In message <20180712183116.GB15892 at raichu>, Mark Johnston writes:

>My plan is to extend cpucontrol(8) to determine the
>correct microcode update for the running system, and have the devcpu-data
>port install the corresponding file to /boot/firmware.

This is problematic when a diskimage is migrated to a different CPU,
only on the second reboot on the new hardware are you certain to
have the correct microcode.

For images which are resurrected on demand on whatever hardware is
available this really problematic.

NB: before anybody misunderstands:  This is not a problem for
guest systems under virtualization - they don't need microcode updates.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.