linux-kernel - Re: 2.6.24-rc8 hangs at mfgpt-timer

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Date:	Thu, 17 Jan 2008 15:57:44 -0700
From:	"Jordan Crouse" <jordan.crouse@....com>
To:	"Arnd Hannemann" <hannemann@...informatik.rwth-aachen.de>
cc:	"Andres Salomon" <dilinger@...ued.net>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.24-rc8 hangs at mfgpt-timer

On 17/01/08 23:52 +0100, Arnd Hannemann wrote:

<snip>

> > Hmmm - not sure whats happening here.  I wonder if we're stuck in an
> > interrupt storm of some sort as soon as you register the interrupt handler.
> > But I would think that whatever was causing the interrupt storm would be
> > running well before we hit setup_irq(), and you would be recording "nobody
> > cared" interrupts left and right.
> 
> Interesting thing is that it hangs not in setup_irq() but later, right
> after printing the newline of the printk.

THat makes me think interrupt storm even more.

> > The thing that scares me is that the TinyBIOS seems to know that we want
> > to use the MFGPT timers, and I wonder if they did anything behind the scenes
> > to "help us out" even though we didn't ask for it.
> > 
> > I don't know how easy it would be for you - but can you try reading 
> > MSRs 0x51400020 - 0x51400023?   If you need a command line app to do it,
> > you can use rdmsr from here:
> > 
> > http://wiki.laptop.org/go/Flashing_LinuxBIOS_on_A-Test_Boards
> 
> MSR register 0x51400020 => b7:ef:5f:f4:bf:d1:95:68
> MSR register 0x51400021 => b7:fd:1f:f4:bf:cf:5a:d8
> MSR register 0x51400022 => b7:f3:bf:f4:bf:f5:fb:a8
> MSR register 0x51400023 => b7:fb:9f:f4:bf:fd:d9:f8

Hmmm - those look wrong.  Is /dev/cpu/0/msr there?  The applet on the
wiki has a bug that doesn't check for it.

Jordan

-- 
Jordan Crouse
Systems Software Development Engineer 
Advanced Micro Devices, Inc.


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