linux-kernel - Re: [PATCH 07/10] cpufreq: Add support for x86 cpuinfo auto loading

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Message-ID: <20111216021254.GG14839@one.firstfloor.org>
Date:	Fri, 16 Dec 2011 03:12:54 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andi Kleen <andi@...stfloor.org>, Borislav Petkov <bp@...64.org>,
	linux-kernel@...r.kernel.org, kay.sievers@...y.org, trenn@...e.de,
	Andi Kleen <ak@...ux.intel.com>, davej@...hat.com
Subject: Re: [PATCH 07/10] cpufreq: Add support for x86 cpuinfo auto loading

On Thu, Dec 15, 2011 at 05:19:46PM -0800, H. Peter Anvin wrote:
> On 12/08/2011 06:37 AM, Andi Kleen wrote:
> >> Well, there is CPUID_8000_0007_EDX[7] which denotes the presence
> >> of the P-state registers. It probably could be added to
> >> init_scattered_cpuid_features() but there's still special handling
> >> needed for K8.
> > 
> > Dave is probably right that it's not worth moving the list.
> > 
> >> Can you do both a family and a feature bit test with the autoprobing
> >> code?
> > 
> 
> Another similar question: is it possible to key a load on more than one
> CPU feature?  It's fairly common that you need more than one feature for
> a specific piece of code to function, and it would be good to be able to
> represent it.

Right now it's not possible. The driver just errors out if it can't
find some additional capability.

I considered it originally, but all the cases I looked at were quite 
obscure (unlikely to happen) so I opted for this simpler setup.

-Andi
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