From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Lutomirski Subject: Re: [2.6.39 regression] hard lock when GNOME starts Date: Fri, 13 May 2011 12:07:59 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Received: from mail-pv0-f177.google.com (mail-pv0-f177.google.com [74.125.83.177]) by gabe.freedesktop.org (Postfix) with ESMTP id 8D6D19E74C for ; Fri, 13 May 2011 09:08:19 -0700 (PDT) Received: by pvh11 with SMTP id 11so1441521pvh.36 for ; Fri, 13 May 2011 09:08:19 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: intel-gfx@lists.freedesktop.org, Chris Wilson List-Id: intel-gfx@lists.freedesktop.org On Fri, May 13, 2011 at 1:38 AM, Andrew Lutomirski wrote: > Hi- > > Something in the range ^8aa7500 40c7f2112ce18fa5eb ^b04d0a90908c > causes by Q67 Sandy Bridge box to lock hard about one second after I > start GNOME. =A0It locks so hard that the reset button doesn't work and > netconsole doesn't say anything. > > I'm about to have trouble finishing the bisection because I've had > trouble running revisions that are older than 2.6.38 and the next bit > of bisection has merge conflicts if I merge in 2.6.38. =A0I can power > through it, but maybe one of you will recognize the bug from the fact > that there aren't that many revisions in there and there can't be many > ways to make the reset button stop working. It's semaphores. I have: 00:02.0 VGA compatible controller: Intel Corporation Sandy Bridge Integrated Graphics Controller (rev 09) which is on a Q67/i7-2600 box. The git history for semaphores is worthless. AFAICT they were disabled around 2.6.38-rc7 by a merge that pulled in a1656b9090f7008d2941c314f5a64724bea2ae37. They were then re-enabled by this commit: commit 47ae63e0c2e5fdb582d471dc906eb29be94c732f Merge: c59a333 467cffb Author: Chris Wilson Date: Mon Mar 7 12:32:44 2011 +0000 Merge branch 'drm-intel-fixes' into drm-intel-next Apply the trivial conflicting regression fixes, but keep GPU semaphores enabled. Conflicts: drivers/gpu/drm/i915/i915_drv.h drivers/gpu/drm/i915/i915_gem_execbuffer.c This pulled in the disable-semaphores patch. So the merge with trivial regression fixes undid the patch that disabled semaphores. This is really annoying for two reasons. One is that the commit message sucks. Two is much worse: the semaphore disabling patch made it into 2.6.38 but this merge went in for 2.6.39. That means that the patch that made my system unusable on 2.6.39 versions *does not exist in the set v2.6.38..v2.6.39-rc7* except as a "trivial" merge. Which means that the two fscking days I spent bisecting this were completely wasted because there was no way that the bisection could have found the bug. In the future, if you change something, that might cause severe breakage, please make it an actual commit. --Andy > > --Andy >