[LinuxBIOS] Intel microcode revision code

Martin.Karlsson at emerson.com Martin.Karlsson at emerson.com
Wed Dec 12 09:28:53 CET 2007


Hello,

Yesterday I wrote some code for the Syslinux boot loader that is meant
to boot different images based on which revision of the CPU microcode
that is currently loaded in the CPU (yes, this is a bit strange but we
have a very good reason for it). I then compared my implementation with
a few others an ran across yours, in
http://www.openbios.org/viewvc/trunk/LinuxBIOSv2/src/cpu/intel/microcode
/microcode.c?view=markup

Question to you guys: why is the first wrmsr instruction there? From my
understanding, by not properly initialising ECX, EAX and EDX this will
overwrite whatever is in the MSR pointed to by ECX?!

BTW I tried out your code on our target hardware (Intel Celeron M, 600
MHz) and with that first wrmsr line in place it hangs and without it, it
runs just fine.

Just wanted to let you know.

Best regards,
Martin Karlsson

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