linux-kernel - Re: [PATCH 3/4] x86/mce: Clarify comments regarding deferred error

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Date:	Wed, 24 Feb 2016 12:37:45 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Aravind Gopalakrishnan <aravind.gopalakrishnan@....com>
Cc:	tony.luck@...el.com, hpa@...or.com, mingo@...hat.com,
	tglx@...utronix.de, dougthompson@...ssion.com,
	mchehab@....samsung.com, x86@...nel.org,
	linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
	ashok.raj@...el.com, gong.chen@...ux.intel.com,
	len.brown@...el.com, peterz@...radead.org, ak@...ux.intel.com,
	alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH 3/4] x86/mce: Clarify comments regarding deferred error

On Tue, Feb 23, 2016 at 05:02:40PM -0600, Aravind Gopalakrishnan wrote:
> On 2/23/16 6:11 AM, Borislav Petkov wrote:
> >On Tue, Feb 16, 2016 at 03:45:10PM -0600, Aravind Gopalakrishnan wrote:
> >>  /* AMD-specific bits */
> >>-#define MCI_STATUS_DEFERRED	(1ULL<<44)  /* declare an uncorrected error */
> >>+#define MCI_STATUS_DEFERRED	(1ULL<<44)  /* declare a deferred error */
> >/* uncorrected error, deferred exception */
> >
> >sounds better to me.
> 
> Hmm. Well, Deferred error is a separate class of error by itself.
> It's neither Corrected in HW nor is it Uncorrected like a MCE.

Let's consult the BKDG:

"Deferred: deferred error.

Read-write; Updated-by-hardware. Cold reset:0.
1=A deferred error was created. A deferred error is the result of an
uncorrectable data error which did not immediately cause a processor
exception; the data is poisoned and an exception is deferred until
the data is loaded by a core. See 2.16.1.10 [Deferred Errors and Data
Poisoning]."

So it is an uncorrected error for which the raising of the error
exception was deferred until consumption.

> If you feel "Uncorrected error, deferred error exception" won;t be
> confusing, that's OK with me.

Why would it be confusing? It is describing exactly what a deferred
error is, albeit a bit too laconic but people can find the longer
description.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.