linux-kernel - Re: i686 quirk for AMD Geode

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Message-ID: <20091117171023.GG15157@caffeine.csclub.uwaterloo.ca>
Date:	Tue, 17 Nov 2009 12:10:23 -0500
From:	lsorense@...lub.uwaterloo.ca (Lennart Sorensen)
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Lennart Sorensen <lsorense@...lub.uwaterloo.ca>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Pavel Machek <pavel@....cz>,
	Matteo Croce <technoboy85@...il.com>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: i686 quirk for AMD Geode

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
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