From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: git-bisect not working correctly in the kvm.git repository? Date: Tue, 18 Nov 2008 22:38:04 +0200 Message-ID: <492327AC.9020007@redhat.com> References: <49226B26.4000807@viscovery.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: walt , git@vger.kernel.org To: Johannes Sixt X-From: git-owner@vger.kernel.org Tue Nov 18 21:39:17 2008 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1L2XLv-00057v-Ua for gcvg-git-2@gmane.org; Tue, 18 Nov 2008 21:39:16 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752359AbYKRUiA (ORCPT ); Tue, 18 Nov 2008 15:38:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752456AbYKRUh7 (ORCPT ); Tue, 18 Nov 2008 15:37:59 -0500 Received: from mx2.redhat.com ([66.187.237.31]:40176 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752200AbYKRUh7 (ORCPT ); Tue, 18 Nov 2008 15:37:59 -0500 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id mAIKbu0M010524; Tue, 18 Nov 2008 15:37:56 -0500 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id mAIKbsbn003129; Tue, 18 Nov 2008 15:37:54 -0500 Received: from mermaid.qumranet.com (vpn-14-29.rdu.redhat.com [10.11.14.29]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id mAIKbpQX014802; Tue, 18 Nov 2008 15:37:52 -0500 User-Agent: Thunderbird 2.0.0.16 (X11/20080723) In-Reply-To: <49226B26.4000807@viscovery.net> X-Scanned-By: MIMEDefang 2.58 on 172.16.27.26 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Johannes Sixt wrote: > If you are pretty sure that the bug you are looking for was *not* > introduced in the branch that was subtree-merged, you can mark it as > "good" like so: > > $ git bisect start kvm-69 kvm-70 $BRANCH > > where $BRANCH is the most recent commit on the subtree-merged branch. > Watch out that you do *not* accidentally pick the *merge* commit that > merged the branch in, but the (second) parent[*], the one that was merged > in. Then your bisect sequence won't ever end up in that branch. > Unfortunately, it is fairly likely that the bug was indeed introduced by the merge, since most of the commits in that repository come via that merge. It is possible that the bug exists in that branch (which you need to build as pure qemu, not kvm), but again, it is more likely that the bug is an interaction between a qemu feature introduced during the merge, and the existing kvm glue code. One way around this is to redo the merge from the point git bisect suggests, but that is difficult, time consuming, and error prone. It also needs a lot of familiarity with the code. Fortunately, long term the problem is going away with qemu upstream gaining kvm support. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.