linux-kernel - Re: [PATCH] [arch-x86] Allow SRAT integrity check to be skipped

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Date:	Tue, 07 Sep 2010 13:03:47 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com>
CC:	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH] [arch-x86] Allow SRAT integrity check to be skipped

On 09/07/2010 12:38 PM, Peter P Waskiewicz Jr wrote:
> 
> It's one SKU of a Nehalem-EX system.  The BIOS for that SKU has an issue
> with resolving SRAT hotplug enumeration, and screws up the table.  Other
> SKU's of this same platform do not have the issue.  Efforts are underway
> to get this BIOS fixed, but in the meantime, there's nothing for users
> to work around the bug (aside from disabling memory hotplug in the
> BIOS).  Another platform almost shipped with the same symptoms, but
> caught it and had it fixed before it shipped (didn't catch it early
> because Windows wasn't failing, and most of the testing on that platform
> was done under Windows).
> 
> I agree with Andi that adding DMI strings would be overkill and would
> leave clutter once the BIOS is fixed.  I look at this patch as a
> stop-gap measure for people to fall back on until a newer BIOS is
> available to correct the NUMA enumeration issues.  Without it, we have
> nothing to point users to when they run into this, waiting for a new
> BIOS.
> 

No, this is exactly the kind of stuff for which a DMI match is ideal.  A
specific system with bounded propagation of the problem.  Thus, the DMI
match acts as a whitelist -- "we know this system and it is safe to
activate this hack on it."  This is a very good thing.

If this is a production BIOS it should have this information.

	-hpa
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