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

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Date:	Thu, 11 Oct 2007 13:30:34 -0400
From:	Dave Jones <davej@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Christoph Egger <Christoph.Egger@....com>,
	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, Oct 11, 2007 at 06:50:12PM +0200, 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.
 
I question the value of adding the printk.
It's not a failure, there's nothing the user can do about it,
and it adds no real value, just more noise to the dmesg.

	Dave

-- 
http://www.codemonkey.org.uk
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