Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754185AbZGTWZ5 (ORCPT ); Mon, 20 Jul 2009 18:25:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753811AbZGTWZz (ORCPT ); Mon, 20 Jul 2009 18:25:55 -0400 Received: from bizon.gios.gov.pl ([195.187.34.71]:49571 "EHLO bizon.gios.gov.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753428AbZGTWZz (ORCPT ); Mon, 20 Jul 2009 18:25:55 -0400 X-Greylist: delayed 1568 seconds by postgrey-1.27 at vger.kernel.org; Mon, 20 Jul 2009 18:25:54 EDT Date: Mon, 20 Jul 2009 23:45:04 +0200 (CEST) From: Krzysztof Oledzki X-X-Sender: ole@bizon.gios.gov.pl To: Linus Torvalds cc: Greg KH , Krzysztof Oledzki , linux-kernel@vger.kernel.org, Andrew Morton , stable@kernel.org, lwn@lwn.net Subject: Re: Linux 2.6.27.27 In-Reply-To: Message-ID: References: <20090720040655.GA11940@kroah.com> <4A645A45.9060509@ans.pl> <20090720151008.GC10015@suse.de> User-Agent: Alpine 1.10 (LNX 962 2008-03-14) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="-1144830174-2062091358-1248126305=:29729" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2300 Lines: 58 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1144830174-2062091358-1248126305=:29729 Content-Type: TEXT/PLAIN; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 8BIT On Mon, 20 Jul 2009, Linus Torvalds wrote: > > > On Mon, 20 Jul 2009, Greg KH wrote: >> >>>> Linus Torvalds (1): >>>> Don't use '-fwrapv' compiler option: it's buggy in gcc-4.1.x >>> >>> I'm very sorry to say that but 2.6.27.27 compiled with gcc-4.2.4 >>> hangs during boot and it is caused by this fix. >>> >>> I extended http://bugzilla.kernel.org/show_bug.cgi?id=13012 with >>> additional info & .config. >> >> Wierd. Linus, any thoughts? Do we need to check the version of the >> compiler that we are using before turning that option off? > > Dang. That was what we hoped to avoid by not using -fwrapv - we didn't > know which compilers were buggy, although it _looked_ like just 4.1.x (I > have some dim memory of somebody suspecting a 4.2.x version too, but that > may have been just a "we know it should only be needed in 4.3.x, so maybe > we shouldn't use it in 4.2.x either"). > > But it looks like the "buggy window" for -fno-strict-overflow is > potentially even _larger_ than it ever was with -fwrapv. And I suspect > that in both cases the real problem is that almost nobody ever uses either > optimization flag, so coverage is way way smaller. > > For now, I suspect we need to do something like this: go back to -fwrapv > (because it has gotten more testing), but limit it to 4.2.x and newer. > > However, it would be really good to figure out _why_ it breaks. It's > probably some specific configuration issue in addition to the particular > kernel vesion (and maybe it even needs some particular hardware to show > the bug - ie a specific driver that triggers it or whatever). No problem. Please let me know what should I do to help tracking this issue. Best regards, Krzysztof Ol?dzki ---1144830174-2062091358-1248126305=:29729-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/