linux-kernel - Re: [PATCH] x86: better CPU identification without the CPUID

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Date:	Sat, 13 Sep 2008 22:55:10 -0700
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"Krzysztof Helt" <krzysztof.h1@...pl>
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, tglx@...utronix.de,
	mingo@...hat.com
Subject: Re: [PATCH] x86: better CPU identification without the CPUID

On Sat, Sep 13, 2008 at 9:43 PM, Yinghai Lu <yhlu.kernel@...il.com> wrote:
> On Sat, Sep 13, 2008 at 3:56 AM, Krzysztof Helt <krzysztof.h1@...pl> wrote:
>> From: Krzysztof Helt <krzysztof.h1@...pl>
>>
>> cpus without the CPUID instruction are identified
>> as general 386 or 486 while some cpus (mostly made
>> by Cyrix) provide c_identify function which identify
>> correctly older cpus using cpu specific registers).
>>
>> Cyrix cpus are even worse as 5x86 and 6x68 have
>> the CPUID instruction disabled. The CPUID is
>> enabled by the c_identify() but the c_identify
>> is only called when the CPUID is available.
>>
>> Fix this by calling the c_identify() for all known
>> cpu families if there is no the CPUID instruction

I updated it to tip/master and call that in early_identify_cpu. it
should solve mtrr detection for Cyrix ...

Please check attached patch.

Thanks

YH

View attachment "identify_cpu_without_cpuid.patch" of type "text/x-patch" (2538 bytes)