Re: banias with different (unusual?) model_name

From: matthias brill
Date: Sat Aug 21 2004 - 06:54:15 EST


hi alan, jeremy

On Fri, Aug 20, 2004 at 02:25:36PM +0100, Alan Cox wrote:
> > i've found a pentium-m banias which reports "Mobile Genuine Intel(R)
> > processor 1400MHz" in /proc/cpuinfo. this (strange?) signature
> > prevents speedstep-centrino.c from working properly.
>
> Signatures appear to be BIOS set so that would make sense.

that fact wasn't obvious to me -- i've updated the BIOS and the strange
banias signature is now gone. it reports the expected "Intel(R)
Pentium(R) M processor 1400MHz" string now.

in excess the "ACPI-behaviour" changes from "totally broken" to "not
working" which is kind of a progress... 8-}


On Fri, Aug 20, 2004 at 07:19:31PM -0700, Jeremy Fitzhardinge wrote:
> Yeah, there seem to be a few of these around. I'm just not certain that
> they're identical to "normal" Banias as far as operating points go.

it seems that the reported value depends on the mental health of the
BIOS-programmer at hand, therefore the suplied string might not be
trustworthy.

if i understand correctly, the type of the cpu can be determined by
looking at the family, model and stepping -- assuming that these values
are reported directly by the CPUID (0FA2) instruction.

the BIOS supplied model_name string in speedstep-centrino.c is parsed to
get the clock cycle time of the cpu. is this actually supposed to be
the "right" way (or worse: the only way) to get this information?


thias

--
Matthias Brill <matthias.brill@xxxxxxxxxxx>

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