linux-kernel - Re: [Bisected] 3.7-rc1 can't resume (still present in 3.9)

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Message-ID: <51E09530.8030300@zytor.com>
Date:	Fri, 12 Jul 2013 16:45:52 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Christian Sünkenberg 
	<christian.suenkenberg@...dent.kit.edu>
CC:	Jonas Heinrich <onny@...ject-insanity.org>,
	"len.brown@...el.com" <len.brown@...el.com>,
	"pavel@....cz" <pavel@....cz>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>, "rjw@...k.pl" <rjw@...k.pl>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [Bisected] 3.7-rc1 can't resume (still present in 3.9)

On 07/12/2013 04:36 PM, Christian Sünkenberg wrote:
> 
> Jonas tried your patch and it fixes suspend/resume on his T43, although
> IMHO the safest approach would be to just add an exception for
> Vendor==Intel && Family==6 && Model==13, or more generally Vendor==Intel
> && !supports_long_mode, as the same erratum also warns about wrmsr
> possibly not triggering a GP either.
> Anyways, at least on this specific MSR with the Pentium M Jonas tested,
> it behaved correctly on every try, so I'd say your patch does the trick,
> thank you very much!
> 

Using vendor matches is not really a great way to deal with things that
can better be handled analytically.

If WRMSR doesn't fault, it is not a problem...

> As a side note, I found a similar erratum #33 in "Pentium® Processor
> Specification Update" for Intel P54C (Family 5, Model 2), which would,
> supposed there are P54C systems with ACPI sleep/resume support, result
> in MSR 0 (P5_MC_ADDR) to be saved and restored instead of nonexistent EFER.

Doesn't really matter, as we'd only read that one after an #MC.

	-hpa


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