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Date: Fri, 23 Mar 2007 12:42:23 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
       Thomas Gleixner <tglx@linutronix.de>,
       Nick Piggin <nickpiggin@yahoo.com.au>, Mingming Cao <cmm@us.ibm.com>,
       Adrian Bunk <bunk@stusta.de>, Andrew Morton <akpm@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Michal Piotrowski <michal.k.k.piotrowski@gmail.com>,
       Mariusz Kozlowski <m.kozlowski@tuxland.pl>,
       Oliver Pinter <oliver.pntr@gmail.com>,
       Sid Boyce <g3vbv@blueyonder.co.uk>, Nick Piggin <npiggin@suse.de>,
       Jens Axboe <jens.axboe@oracle.com>, Thomas Renninger <trenn@suse.de>,
       Len Brown <len.brown@intel.com>
Subject: Re: [1/6] 2.6.21-rc4: known regressions
Message-ID: <20070323114223.GA23483@elte.hu>
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there's a new post-rc4 regression: my T60 hangs during early bootup. I 
bisected the hang down to this recent commit:

| commit 25496caec111481161e7f06bbfa12a533c43cc6f
| Author: Thomas Renninger <trenn@suse.de>
| Date:   Tue Feb 27 12:13:00 2007 -0500
|
|    ACPI: Only use IPI on known broken machines (AMD, Dothan/BaniasPentium M)

undoing this change fixes my T60 so it correctly boots again.

the commit has this confidence-raising comment:

|   However, I am not sure about the naming of the parameter and how it 
|   could/should get integrated into the dyntick part 
|   (CONFIG_GENERIC_CLOCKEVENTS). There, a more fine grained check (TSC 
|   still running?, ..) is needed?

could we please revert this commit until it's done correctly?

and did this end up being a 'fix'? The change weakens the scope of a 
hardware workaround, which IMO has no place so late in the cycle. At a 
minimum the clockevents maintainer (Thomas) should have been Cc:-ed on 
it.

	Ingo