linux-kernel - Re: [PATCH 01/10] Add driver auto probing for x86 features

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Message-ID: <20111209212842.0b2ec9c7@endymion.delvare>
Date:	Fri, 9 Dec 2011 21:28:42 +0100
From:	Jean Delvare <khali@...ux-fr.org>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	kay.sievers@...y.org, trenn@...e.de, davej@...hat.com,
	axboe@...nel.dk, hpa@...or.com, herbert@...dor.apana.org.au,
	ying.huang@...el.com, lenb@...nel.org
Subject: Re: [PATCH 01/10] Add driver auto probing for x86 features

On Fri, 09 Dec 2011 12:24:47 -0800, Andi Kleen wrote:
> 
> > Can you guarantee that there is no asymmetric system already working
> > today?
> 
> I used to have an asymmetric system myself, but we generally subset the 
> CPU feature
> flags to be the same everywhere and I didn't change any per CPU stepping 
> checks
> as they were there.
> 
> >   If you can't, then your approach could cause a regression. This
> > is why I am asking for an API change to let drivers pass a specific CPU
> > to x86_match_cpu(). There are at least two drivers who would take
> > benefit of this. Your patch set is supposed to only add driver
> > auto-loading, and while cleaning up the code in the process is nice, I
> > think you should avoid driver behavior changes, these are out of scope
> > for such a patch set.
> 
> I undoed that change to the coretemp driver

Thanks.

> and there's no other AFAIK.

via-cputemp was affected as well.

> Generally most drivers only check the boot cpu.

-- 
Jean Delvare
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