[LinuxBIOS] Intel microcode revision code

ron minnich rminnich at gmail.com
Wed Dec 12 17:19:43 CET 2007

On Dec 12, 2007 12:28 AM,  <Martin.Karlsson at emerson.com> wrote:
> 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.

Thanks Martin. That looks like quite a nice bug catch you've done :-)

We'll have to figure out if this code was ever (a) used and (b) worked :-)

Thanks again, this is great!


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