From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753737Ab1K2M0o (ORCPT ); Tue, 29 Nov 2011 07:26:44 -0500 Received: from marge.uochb.cas.cz ([147.231.129.3]:44919 "EHLO marge.uochb.cas.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751659Ab1K2M0m (ORCPT ); Tue, 29 Nov 2011 07:26:42 -0500 Message-ID: <4ED4CF7C.8020808@atlas.cz> Date: Tue, 29 Nov 2011 13:26:36 +0100 From: Clarinet User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0) Gecko/20111105 Thunderbird/8.0 MIME-Version: 1.0 To: John Stultz CC: Jiri Polach , 647095@bugs.debian.org, Jonathan Nieder , Ben Hutchings , LKML , x86@kernel.org Subject: Re: CPU hyperthreading turned on after soft power-cycle 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> <1321574019.25715.52.camel@work-vm> <4ECA51B9.3010707@seznam.cz> <1321905728.6445.2.camel@work-vm> <4ECAC340.8090908@atlas.cz> <1322533915.24090.69.camel@work-vm> In-Reply-To: <1322533915.24090.69.camel@work-vm> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Using an older "known-good" kernel, could you build and run the test > case at the end of Documentation/rtc.txt a few times and see if it > triggers the same problem? > > I'm suspicious that the setting the alarm is whats tripping the BIOS > into enabling the HT bit. Because with older kernels, we used PIE mode > irqs which hwclock usually uses at boot, but with newer kernels, we > emulate PIE via AIE alarm mode. So if the BIOS was broken before, you > wouldn't have noticed unless you tried to use AIE irqs. > > If this doesn't work, I'll get some patches to both 2.6.27 and 2.6.28 > kernels to debug the exact flow of how we're touching the hardware and > then we can further narrow it down. I ran the tests the following way: - boot 2.6.37.6 - check /proc/cpuinfo - 12 processors - halt - boot 2.6.37.6 - check /proc/cpuinfo - 12 processors - run rtctest - reboot - boot 2.6.37.6 - check /proc/cpuinfo - 12 processors - halt - boot 2.6.37.6 - check /proc/cpuinfo - 12 processors - run rtctest - halt - boot 2.6.37.6 - check /proc/cpuinfo - 24 processors So the conclusion is that only if rtctest is run and the machine is halted, it triggers the HT problem. Reboot seems to "neutralize" whatever rtctest did. Jiri