linux-kernel - Re: Hibernate resume bug around 3,18-rc2

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Message-ID: <20151124224606.GD9528@wotan.suse.de>
Date:	Tue, 24 Nov 2015 23:46:06 +0100
From:	"Luis R. Rodriguez" <mcgrof@...e.com>
To:	Juergen Gross <jgross@...e.com>
Cc:	vasvir@....demokritos.gr, linux-kernel@...r.kernel.org,
	Toshi Kani <toshi.kani@...com>
Subject: Re: Hibernate resume bug around 3,18-rc2 - Full PAT support

On Mon, Nov 23, 2015 at 03:19:16PM +0100, Juergen Gross wrote:
> On 23/11/15 15:11, vasvir@....demokritos.gr wrote:
> > Ok I will send the .config when I get back home. I have all kernels I
> > build in .deb archive. The problem is that the debian kernel build
> > procedure does not hold somewhere in the deb file the git commit hash.
> > 
> > Fow which kernel would you care to see the config? 4.3?
> 
> Doesn't really matter anymore. I've posted a patch already to fix it and
> got the reply, that the fix is okay, but no harm can come from the
> current implementation, as the two config options are always either both
> set or reset.

Hrm, Vassilis seems to be able to reproduce this more effectively by heating up
his CPU prior to hibernation though. I have no idea what adding APIC_LVT_MASKED
((1 << 16)) to the Local Vector Table (LVT) Thermal Monitor (APIC_LVTTHMR 0x330) does but
clear_local_APIC() seems to be used to "cleanout any BIOS leftovers during
boot." If we're suspending but the fan is still on I wonder if this could cause
an issue with some settings the BIOS may have set prior to hibernation, and
a mismatch upon resume.

I can't find what APIC_LVT_MASKED does though, the best doc I found:

https://www-ssl.intel.com/content/dam/www/public/us/en/documents/white-papers/cpu-monitoring-dts-peci-paper.pdf

The inability to set the MTRR for the i915 card might be totally separate
issue at this point, not sure. One could test that I suppose by just
using vesa graphics card driver (disabling i915) to at least get
a basic screen to see things and compile/test things.

  Luis
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