linux-kernel - Re: 2.6.23-rc4-mm1 and -rc6-mm1: boot failure on HP nx6325, related to clockevents

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Date:	Tue, 25 Sep 2007 23:28:54 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Andi Kleen <ak@...e.de>, Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>
Subject: Re: 2.6.23-rc4-mm1 and -rc6-mm1: boot failure on HP nx6325, related to clockevents

Thomas,

On Tuesday, 25 September 2007 22:46, Thomas Gleixner wrote:
> Rafael,
> 
> On Tue, 2007-09-25 at 22:07 +0200, Rafael J. Wysocki wrote:
> > On Tuesday, 25 September 2007 15:17, Thomas Gleixner wrote:
> > > On Tue, 2007-09-25 at 15:16 +0200, Rafael J. Wysocki wrote:
> > [--snip--]
> > > 
> > > I start to get desperate. Below is a patch, which moves the apic timer
> > > disable check after the calibration routine. Can you please apply on top
> > > of -hrt and add "noapictimer" to the command line ? Does it boot ?
> >
> > 2.6.23-rc7 with patch-2.6.23-rc7-hrt1.patch and the patch below applied boots
> > with noapictimer and doesn't boot without it.
> 
> That was expected. I explicitly asked to add "noapictimer" to the kernel
> command line.
> 
> Ok, so we ruled out the apic timer calibration routine. I did not expect
> that this would be the culprit, but with "dark screen" as the only debug
> info, I need to resort to small steps.
> 
> Can you please send me the output of /proc/timer_list of 2.6.23-rc7-hrt1
> after booting with "noapictimer" ?

Sure, attached.  [Note: the kernel has been compiled with both NO_HZ and
HIGH_RES_TIMERS unset.]

> I'm a bit confused by your earlier confirmation, that mainline w/o the
> -hrt patches boots fine, when you add "apicmaintimer" to the kernel
> command line. "apicmaintimer" stops the PIT like we do in -hrt and we
> just use the local APIC timer for everything. Can you please retest and
> confirm that this is correct ?

No, it's not.  The mainline _usually_ doesn't boot with "apicmaintimer".

It seems to me that _sometimes_ the CPU just doesn't enter this C1E state
and then everything goes fine ...

> Is the 32 bit kernel working on that box ?

Can't tell, I have only 64-bit userland here.

> Thanks for your patience.

Well, I'm only making sure that future kernels will run on my box. ;-)

> 	tglx
> 
> PS: I just sent out the "disable APIC timer for AMD C1E boxen" patch.

Yes, I've already tested it and sent a reply.  It works. :-)

> We debugged this half a year ago on a nx6325, but I completely forgot about
> that. The explanation from AMD was sensible, but your "apicmaintimer"
> works statement is contradictory.

Well, it was wrong.

I have some problems with resuming from suspend to RAM using 2.6.23-rc8-mm1
with this patch applied, but I think they are related to something else.  I'll
wait for the next -mm with debugging that.

For now, I'm going to build 2.6.23-rc8 with my collection of suspend patches
plus patch-2.6.23-rc7-hrt1.patch and the "disable APIC timer for AMD C1E boxes"
patch applied.  I'll play with that a bit and let you know how it's behaving.

Greetings,
Rafael

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