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

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Date:	Thu, 11 Oct 2007 16:55:36 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Christoph Egger <Christoph.Egger@....com>
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 Thu, 11 Oct 2007, Christoph Egger wrote:

> On Thursday 11 October 2007 15:51:49 Thomas Gleixner wrote:
> > On Thu, 11 Oct 2007, Joerg Roedel wrote:
> > > MCG_CAP never reports a negative count of available error-reporting
> > > banks. Therefore, make nr_mce_banks unsigned.
> > > Check for MCA/MCE feature bits as early as possible.
> > >
> > > +
> > > +	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.
 
	tglx
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