From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754703Ab1KQXy2 (ORCPT ); Thu, 17 Nov 2011 18:54:28 -0500 Received: from e31.co.us.ibm.com ([32.97.110.149]:58503 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752634Ab1KQXy1 (ORCPT ); Thu, 17 Nov 2011 18:54:27 -0500 Message-ID: <1321574019.25715.52.camel@work-vm> Subject: Re: CPU hyperthreading turned on after soft power-cycle From: John Stultz To: Jiri Polach Cc: 647095@bugs.debian.org, Jonathan Nieder , Ben Hutchings , LKML , x86@kernel.org Date: Thu, 17 Nov 2011 15:53:39 -0800 In-Reply-To: <4EC59BCE.6050902@atlas.cz> References: <20111030110543.5872.61279.reportbug@supermicro.uochb.cas.cz> <1319988329.6759.88.camel@deadeye> <4EAE9D3A.7000108@atlas.cz> <4EB92181.5030500@seznam.cz> <20111110015212.GB2399@elie.gateway.2wire.net> <4EBD2825.6050806@atlas.cz> <4EC43DF7.4010902@atlas.cz> <1321561946.25715.16.camel@work-vm> <4EC59BCE.6050902@atlas.cz> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.1- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 x-cbid: 11111723-7282-0000-0000-000003E4627B Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2011-11-18 at 00:42 +0100, Jiri Polach wrote: > On 11/17/2011 9:32 PM, John Stultz wrote: > > On Wed, 2011-11-16 at 23:49 +0100, Clarinet wrote: > >> Hi all, > >> > >>>> Result of bisecting: v2.6.38-rc1 exhibits the problem. v2.6.37 and > >>>> many of the topic branches merged in the 2.6.38 merge window work ok. > >>>> Some other topic branches do not boot at all. > >>>> > >>>> Jiri: if you have gitk installed, then "git bisect visualize" can help > >>>> get a sense of what's in the middle of the regression range. > >>>> "gitk --bisect --first-parent v2.6.37..v2.6.38-rc1" might be a good way > >>>> to find mainline commits to test before finding a topic branch to delve > >>>> into. > >>> > >>> I have been able to narrow the interval manually a little bit from the > >>> "top" (the bad side) and I will go on from the bottom now. However, > >>> there seems to be a large area where kernels are unbootable for me - > >>> they mostly stop when init is called and I do not know why. > >> > >> Finally! After another 50+ compilations a have it! It took some time as > >> first I had to find a reason why some revisions did not boot (almost 2/3 > >> were unbootable and the first bad commit was among them). Having this > >> solved I have been able to bisect without "skipping". The result is > >> surprising (at least for me) - believe it or not, the first bad commit > >> is 6610e089 "RTC: Rework RTC code to use timerqueue for events" from > >> John Stultz (I am sending him a copy of this message). > >> > >> I would never expect this would be a problem, but my understanding of > >> this commit is very limited, so I am certainly missing the point. > >> However, I have tried to compile 2.6.38 (which was "bad") with "Real > >> Time Clock" configuration option turned off and it behaves "normally" > >> then (= is "good"). > > > > Huh. That's *very* odd. Is your system doing anything in-particular > > with the RTC? I don't have a clue right off, so probably the next step > > Yes, it is very odd. The system does not do anything special with RTC. > It is a diskless computational workstation. > > > is doing a bit of instrumentation to try to figure out where exactly we > > trigger the behavior. Could you checkout commit 6610e089 and apply the > > patch below to see if we can't narrow it down? > > With the patch applied the system does not show the strange behavior (= > is "good"). > > > Could you also send your .config to me? > > Sure. It is attached. I have found that if I turn CONFIG_RTC_DRV_CMOS > off, the system behaves normally (= is "good") too. Yea. My rough guess is that the BIOS is somehow sensitive to how the CMOS RTC is touched. Does disabling CONFIG_HPET_EMULATE_RTC change the behavior? thanks -john