Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754833AbZGUKRZ (ORCPT ); Tue, 21 Jul 2009 06:17:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754802AbZGUKRY (ORCPT ); Tue, 21 Jul 2009 06:17:24 -0400 Received: from bizon.gios.gov.pl ([195.187.34.71]:44969 "EHLO bizon.gios.gov.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754634AbZGUKRY (ORCPT ); Tue, 21 Jul 2009 06:17:24 -0400 Date: Tue, 21 Jul 2009 12:16:05 +0200 (CEST) From: Krzysztof Oledzki X-X-Sender: ole@bizon.gios.gov.pl To: Linus Torvalds cc: Greg KH , 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="-1144830174-1490931129-1248171366=:29729" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3200 Lines: 80 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1144830174-1490931129-1248171366=:29729 Content-Type: TEXT/PLAIN; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 8BIT On Tue, 21 Jul 2009, Krzysztof Oledzki wrote: > > > On Mon, 20 Jul 2009, Linus Torvalds wrote: > >> >> >> On Mon, 20 Jul 2009, Krzysztof Oledzki wrote: >>> >>> No problem. Please let me know what should I do to help tracking this >>> issue. >> >> Can you build two kernels: one with -fwrapv, and one with >> -fno-strict-overflow, and then verify that >> >> - they are otherwise identical (ie exact same source code, same compiler >> etc) >> >> - verify that yes, the -fwrapv kernel works, the other does not. Just to >> avoid the confusion that obviously exists with Debian/sid binutils >> upgrades that _also_ happens result in nonbootable kernels. >> >> - upload the 'vmlinux' images somewhere (I'm not sure what the limits for >> binary attachments are at the kernel bugzilla, but that would be the >> logical place) >> >> In fact, it would be nice to have a third "identical" kernel build, except >> with neither -fwrapv/-fno-strict-overflow. > > OK. Right now I'm building the three kernels you asked for > (fwrapv/fno-strict-overflow/none). I'll test them and upload vmlinux images. OK, there are three kernels, exactly as you requested: http://noc.axelspringer.pl/no-strict-overflow-vs-wrapv/vmlinux-fno-strict-overflow.bz2 (Hangs) http://noc.axelspringer.pl/no-strict-overflow-vs-wrapv/vmlinux-fwrapv.bz2 (OK) http://noc.axelspringer.pl/no-strict-overflow-vs-wrapv/vmlinux-fnone.bz2 (OK) # grep -A1 "can't wrap" linux-2.6.27.27-*/Makefile linux-2.6.27.27-fno-strict-overflow/Makefile:# disable invalid "can't wrap" optimzations for signed / pointers linux-2.6.27.27-fno-strict-overflow/Makefile-KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow) -- linux-2.6.27.27-fwrapv/Makefile:# disable invalid "can't wrap" optimzations for signed / pointers linux-2.6.27.27-fwrapv/Makefile-KBUILD_CFLAGS += $(call cc-option,-fwrapv) -- linux-2.6.27.27-fnone/Makefile:# disable invalid "can't wrap" optimzations for signed / pointers linux-2.6.27.27-fnone/Makefile-#KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow) Plwase note the third one has the KBUILD_CFLAGS commented. Kernels are identical and are compiled from the same config, on the same server with gcc-4.2.4, binutils-2.19. There is no ccache installed and the kernels are not patched with any additonal patches - just vanilla linux-2.6.27.27. Screenshot from the hanging kernel (-fno-strict-overflow): http://noc.axelspringer.pl/no-strict-overflow-vs-wrapv/2.6.27.27-hang.png Dmesg from a bootable kernel: http://noc.axelspringer.pl/no-strict-overflow-vs-wrapv/dmesg Best regards, Krzysztof Ol?dzki ---1144830174-1490931129-1248171366=: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/