From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: AAARGH bisection is hard (Re: [2.6.39 regression] X locks up hard right after logging in) Date: Fri, 13 May 2011 11:41:46 -0700 Message-ID: References: <4DCD79A0.7000500@kdbg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Andrew Lutomirski , Christian Couder , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, git@vger.kernel.org, Shuang He To: Johannes Sixt X-From: linux-kernel-owner@vger.kernel.org Fri May 13 20:42:49 2011 Return-path: Envelope-to: glk-linux-kernel-3@lo.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1QKxK4-0007uQ-Sm for glk-linux-kernel-3@lo.gmane.org; Fri, 13 May 2011 20:42:49 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756359Ab1EMSml convert rfc822-to-quoted-printable (ORCPT ); Fri, 13 May 2011 14:42:41 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:53495 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753061Ab1EMSmj convert rfc822-to-8bit (ORCPT ); Fri, 13 May 2011 14:42:39 -0400 Received: from mail-vw0-f46.google.com (mail-vw0-f46.google.com [209.85.212.46]) (authenticated bits=0) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id p4DIg7U4015764 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=FAIL); Fri, 13 May 2011 11:42:08 -0700 Received: by vws1 with SMTP id 1so2024371vws.19 for ; Fri, 13 May 2011 11:42:06 -0700 (PDT) Received: by 10.52.176.136 with SMTP id ci8mr2413046vdc.234.1305312126058; Fri, 13 May 2011 11:42:06 -0700 (PDT) Received: by 10.52.181.98 with HTTP; Fri, 13 May 2011 11:41:46 -0700 (PDT) In-Reply-To: <4DCD79A0.7000500@kdbg.org> X-Spam-Status: No, hits=-102.977 required=5 tests=AWL,BAYES_00,USER_IN_WHITELIST X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.63 on 140.211.169.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: On Fri, May 13, 2011 at 11:34 AM, Johannes Sixt wrote: > Am 13.05.2011 19:54, schrieb Linus Torvalds: >> For example, in your case, since you had certain requirements of >> support that simply didn't exist earlier, something like >> >> =A0 =A0git bisect requires v2.6.38 >> >> would have been really useful - telling git bisect that any commit >> that cannot reach that required commit is not even worth testing. > > You can already have this with > > =A0 git bisect good v2.6.38 > > It sounds a bit unintuitive, but with a slight mind-twist it can even= be > regarded as correct in a mathematical sense: when the precondition is > false, the result is true. ;-) No. That's not the same thing AT ALL. When you say that v2.6.38 is good, that means that everything that can be reached from 2.6.38 is good. NOT AT ALL the same thing as "git bisect requires v2.6.38" would be. The "requires v2.6.38" would basically say that anything that doesn't contain v2.6.38 is "off-limits". It's fine to call them "good", but that's not the same thing as "git bisect good v2.6.38". Why? Think about it. It's the "reachable from v2.6.38" vs "cannot reach v2.6.38" difference. That's a HUGE difference. Linus