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

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Date:	Thu, 02 May 2013 02:45:43 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	"H. Peter Anvin" <hpa@...or.com>,
	Jonas Heinrich <onny@...ject-insanity.org>
Cc:	len.brown@...el.com, pavel@....cz, tglx@...utronix.de,
	mingo@...hat.com, x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	Jarkko Sakkinen <jarkko.sakkinen@...el.com>
Subject: Re: [Bisected] 3.7-rc1 can't resume (still present in 3.9)

On Wednesday, May 01, 2013 11:55:10 AM H. Peter Anvin wrote:
> On 05/01/2013 11:51 AM, Jonas Heinrich wrote:
> > Well, you could give me instructions on how to debug this (I'll do 
> > everything ;)) or I could ship you the Thinkpad T43. I guess this
> > would worth the effort since this bug is somehow critical.
> > 
> > Best regards, Jonas
> 
> I'll put together a debug patch unless I can trick Rafael into doing
> it first...

I'm afraid that code has changed quite a bit since I looked at it last time.
[Jarkko Sakkinen seems to have worked on it lately, CCed.]

Jonas, I wonder what happens if you drop the first hunk of the patch (it just
uses a different register, which shouldn't matter)?  Does it still help then?

If so, there are still a few things you can do to it, e.g:
(1) drop the

-       btl     $WAKEUP_BEHAVIOR_RESTORE_CR4, %edi
-       jnc     1f

lines,
(2) drop the

-       btl     $WAKEUP_BEHAVIOR_RESTORE_EFER, %edi
-       jnc     1f

lines,
(3) drop the

+       jecxz   1f

line,
(4) drop the

+       movl    %eax, %ecx
+       orl     %edx, %ecx
+       jz      1f

lines and see what the minimal patch needed for things to work again is.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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