linux-kernel - Re: [PATCH 1/2] x86: don't enable MCE after suspend/resume when system was booted with "nomce"

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Date:	Mon, 15 Dec 2008 23:23:03 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Andreas Herrmann <andreas.herrmann3@....com>
Cc:	Andi Kleen <andi@...stfloor.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] x86: don't enable MCE after suspend/resume when system was booted with "nomce"

> > http://git.kernel.org/?p=linux/kernel/git/mingo/linux-2.6-x86.git;a=commit;h=81c7af997dafbabad464ccefba89af2b247899da
> 
> Thanks for that pointer.
> I didn't look at tip/x86/mce up to know. Is this .28 material?

I would think so, but I'm not sure the x86 maintainers think the same.

> My fix is intended for .28.
> 
> I didn't care about the lurking sysfs interface when booted with
> "nomce".  It's there and you could enable MCE with changing attributes
> but then you are actively fiddling with MCE.
> 
> The fix is for the more severe problem that mce_init() is called on
> resume and thus will enable MCE (setup cr4 and corresponding MSRs)
> which shouldn't happen when booted with "nomce".

The patch does the same (although the description doesn't say that). 
When there is no sysfs interface there won't
be any resume either because resume goes through the sysdev devices. 
So it's a cleaner and more complete fix imho.

-Andi
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