linux-kernel - RE: [PATCH 1/3] mce: Add a msg string to the MCE tracepoint

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Message-ID: <3908561D78D1C84285E8C5FCA982C28F040ACC@ORSMSX104.amr.corp.intel.com>
Date:	Thu, 1 Mar 2012 18:28:47 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Borislav Petkov <bp@...64.org>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
CC:	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Ingo Molnar <mingo@...e.hu>,
	EDAC devel <linux-edac@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/3] mce: Add a msg string to the MCE tracepoint

> > My concern is; on Sandy Bridge, is it safe to gather info about the DIMM
> > location in/from machine check context in a reasonable time span?
>
> Well, what amd64_edac does is "buffer" the required lookup info so
> whenever you get an error, you simply lookup the channel and chip select
> - all ops which can be done in atomic context.

Yes - we could pre-read all the config space registers ahead of time and
save them in memory (none of the values should change - except if the platform
supports hot-plug for memory). Total is only a few Kbytes. Then decode in
machine check context is both safe, and fast.

-Tony
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