linux-kernel - Re: [PATCH -tip] x86: cpu/proc.c adding extended_cpuid

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Message-Id: <1244652044.3295.10.camel@ht.satnam>
Date:	Wed, 10 Jun 2009 22:10:44 +0530
From:	Jaswinder Singh Rajput <jaswinder@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -tip] x86: cpu/proc.c adding extended_cpuid_level for
 /proc/cpuinfo

Hello Peter,

On Sat, 2009-06-06 at 09:53 +0530, Jaswinder Singh Rajput wrote:
> On Fri, 2009-06-05 at 13:55 -0700, H. Peter Anvin wrote:
> > Jaswinder Singh Rajput wrote:
> > > Hello Andrew,
> > > 
> > > On Tue, 2009-05-12 at 23:21 -0700, Andrew Morton wrote:
> > >> On Tue, 12 May 2009 12:44:42 +0530 Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:
> > >>
> > >>> +		   "ext cpuid level\t: 0x%x\n"
> > >> It's unobvious what "ext" means.  External?
> > >>
> > >> Can we make it "extended cpuid level"?
> > > 
> > > extended cpuid level will look like this :
> > > 
> > > fpu		: yes
> > > fpu_exception	: yes
> > > cpuid level	: 5
> > > wp		: yes
> > > extended cpuid level: 0x80000008
> > > flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe constant_tsc pebs bts pni dtes64 monitor ds_cpl cid
> > > 
> > 
> > The more I'm thinking about this I think it was a mistake to put cpuid
> > level: there in the first place, too.  My opinion is increasingly to
> > leave this to x86info or other user-space tools.
> > 
> 
> cpuid level is as important as cpu family, model and stepping.
> 
> For Intel, in some cases cpuid level is more important then cpu family,
> model and stepping. Like you cannot tell by looking at cpu family, model
> and stepping which model is new and which is old like 05_01 or 06_1A or
> 0F_03H ?
> 
> But by looking at cpuid level and extended cpuid level you can tell
> which is new and which is old and which supports more features.
> 
> So cpuid level and extended cpuid level is better scale than cpu family,
> model and stepping. So I think hiding this valuable information is a
> crime.
> 

                                              Highest Value in EAX
 Intel 64 or IA-32 Processors   Basic Information             Extended Function
                                                                 Information
Earlier Intel486 Processors   CPUID Not Implemented       CPUID Not Implemented
Later Intel486 Processors and          01H                     Not Implemented
Pentium Processors
Pentium Pro and Pentium II             02H                     Not Implemented
Processors, Intel Celeron
Processors
Pentium III Processors                 03H                     Not Implemented
Pentium 4 Processors                   02H                       80000004H
Intel Xeon Processors                  02H                       80000004H
Pentium M Processor                    02H                       80000004H
Pentium 4 Processor                    05H                       80000008H
supporting Hyper-Threading
Technology
Pentium D Processor (8xx)              05H                       80000008H
Pentium D Processor (9xx)              06H                       80000008H
Intel Core Duo Processor               0AH                       80000008H
Intel Core 2 Duo Processor             0AH                       80000008H
Intel Xeon Processor 3000,             0AH                       80000008H
5100, 5200, 5300, 5400
Series
Intel Core 2 Duo Processor             0DH                       80000008H
8000 Series
Intel Xeon Processor 5200,             0AH                       80000008H
5400 Series
Intel Atom Processor                   0AH                       80000008H
Intel Core i7 Processor                0BH                       80000008H

cpuid level and extended cpuid level tells the information about Intel
processor model.
Do you still think it is useless and should not be present
in /proc/cpuinfo .

Thanks,
--
JSR

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