linux-kernel - Re: [PATCH 1/2] x86: mce init optimization and signedness fixup

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Date:	Fri, 12 Oct 2007 09:44:02 +0200
From:	"Christoph Egger" <Christoph.Egger@....com>
To:	"Thomas Gleixner" <tglx@...utronix.de>
cc:	"Joerg Roedel" <joerg.roedel@....com>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] x86: mce init optimization and signedness fixup

On Thursday 11 October 2007 18:50:12 Thomas Gleixner wrote:
> On Thu, 11 Oct 2007, Christoph Egger wrote:
> > On Thursday 11 October 2007 16:55:36 Thomas Gleixner wrote:
> > > > > > +
> > > > > > +	if (!cpu_has(c, X86_FEATURE_MCA) || !cpu_has(c,
> > > > > > X86_FEATURE_MCE)) { +		printk(KERN_INFO "CPU%i: No machine check
> > > > > > support available\n", +			smp_processor_id());
> > > > > > +		return;
> > > > >
> > > > > This breaks winchip MCE support.
> > > >
> > > > First, what is a winchip? It sounds to be something windows specific.
> > > > ;) Second, can you explain in which way MCE support gets broken,
> > > > please?
> > >
> > > First, winchip is the code name of Centaurs early x86 cpus.
> > >
> > > Second, those beasts do not have FEATURE_MCA, but they have
> > > FEATURE_MCE, so they support the fatal exception, but not the non fatal
> > > check.
> >
> > So when I change the above code snippet to:
> >
> > +	if (!cpu_has(c, X86_FEATURE_MCE)) {
> > +		printk(KERN_INFO "CPU%i: No machine check support available\n",
> > +			smp_processor_id());
> > +		return;
> >
> > Would this make the whole patch acceptable then?
>
> Yeah, but then we can clean up the extra checks for _MCE in the various
> cpu type init functions as well.

Will you do the little modification in your tree after applying my patch
or do you want me to resend the patch with that little modification.

Christoph


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