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 12:01:32 +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 Wed, Aug 14, 2013 at 09:15:04PM -0300, Mauro Carvalho Chehab wrote:
> > - Two, if ghes_edac is enabled, it prevents other edac drivers
> > from being loaded. It looks like the assumption here is that if
> > ghes/firmware first is enabled, then *all* memory errors are
> > reported through ghes which is not true. We could have (a subset
> > of) corrected errors reported through ghes, some through CMCI
> > and uncorrected errors through MCE. So, if I'm not mistaken, if
> > ghes_edac is enabled, we will only receive ghes error events through
> > mc_event and not the others. Mauro, is this accurate?
> 
> Yes, that's the current assumption. It prevents to have both BIOS and a
> direct-hardware-access-EDAC-driver to race, as this is known to have
> serious issues.

Ok, this is getting confusing so let's shed some more light.

* First of all, Naveen is asking whether other *edac* drivers can
be loaded. And no, they cannot once the ghes thing is loaded which
potentially is a problem.

For example, if the chipset-specific driver has additional functionality
from ghes_edac, then that functionality is gone when ghes_edac loads
first. This might be a problem in some cases, we probably need to think
about this more in depth.

* Then, there's the trace_mce_record() TP which comes straight
from mce.c This one is always enabled unless the mce_disable_bank
functionality kicks in which you, Naveen, added :-).

* The CMCI stuff should be synchronized with the MCE TP so that should
be ok.

I think those are our current error reporting paths...

-- 
Regards/Gruss,
    Boris.

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