Re: i686 quirk for AMD Geode

Lennart Sorensen
2009-11-17T17:10:24Z

On Tue, Nov 17, 2009 at 08:43:45AM -0800, H. Peter Anvin wrote:
> On 11/17/2009 06:34 AM, Lennart Sorensen wrote:
> > On Tue, Nov 17, 2009 at 11:59:29AM +0000, Alan Cox wrote:
> >>> Trying rdmsr from msr-tools 1.2 gives me:
> >>>
> >>> # ./rdmsr -x 0x00001810
> >>> rdmsr: CPU 0 cannot read MSR 0x00001810
> >>>
> >>> Hmm, now what?
> >>
> >> Beats me - I thought the region registers were read/write.
> >
> > Actually it seems I can't read any MSRs on it.
> >
> > Using the same kernel, same msr module, same rdmsr on a Geode LX system
> > works fine. I can read MSRs no problem. Seems the msr module isn't
> > working on the Geode SC1200 (and hence possibly the GX1).
> >
>
> That would seem highly unlikely ... unless the MSR flag isn't exposed in
> CPUID.

That would be odd yes.

# cat /proc/cpuinfo
processor : 0
vendor_id : CyrixInstead
cpu family : 5
model : 9
model name : Geode(TM) Integrated Processor by National Semi
stepping : 1
cpu MHz : 266.612
cache size : 16 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu tsc msr cx8 cmov mmx cxmmx
bogomips : 534.41
clflush size : 32
power management:

That part looks OK. So why is reading MSRs not working on this stupid
CPU at any of the addresses the data book says should work.

--
Len Sorensen