linux-kernel - Re: [PATCH 3/3] mce: acpi/apei: trace: Enable ghes memory error trace event

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Date:	Thu, 15 Aug 2013 15:51:06 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Mauro Carvalho Chehab <m.chehab@...sung.com>
Cc:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
	"Luck, Tony" <tony.luck@...el.com>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>,
	"rjw@...k.pl" <rjw@...k.pl>,
	"lance.ortiz@...com" <lance.ortiz@...com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Aristeu Rozanski Filho <arozansk@...hat.com>
Subject: Re: [PATCH 3/3] mce: acpi/apei: trace: Enable ghes memory error
 trace event

On Thu, Aug 15, 2013 at 10:34:21AM -0300, Mauro Carvalho Chehab wrote:
> Yes, but the thing is that it is not safe to use the hardware driver
> if the BIOS is also reading the hardware error registers directly, as,
> on several hardware, a read cause the error data to be cleaned on such
> register.

Here's the deal:

* We parse some APEI table and disable those MCA banks which the BIOS
wants to handle first.

* When the BIOS decides to report an error from that handling, it does
so over another BIOS table.

* Now you have two possibilities:

** On systems without an edac driver or where it doesn't make sense to
have the ghes_edac driver, we call trace_mc_event() straight from APEI
code (this is what we're currently discussung).

** On other systems, where we need ghes_edac, we *don't* use the
trace_mc_event() tracepoint in the APEI code but let it come from
ghes_edac with additional information collected by edac.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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