From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LhJrc-0006p0-Gm for qemu-devel@nongnu.org; Wed, 11 Mar 2009 04:32:32 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LhJrb-0006nn-LL for qemu-devel@nongnu.org; Wed, 11 Mar 2009 04:32:31 -0400 Received: from [199.232.76.173] (port=33296 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LhJrb-0006nX-Fd for qemu-devel@nongnu.org; Wed, 11 Mar 2009 04:32:31 -0400 Received: from hall.aurel32.net ([88.191.82.174]:33663) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LhJrb-0003I3-0S for qemu-devel@nongnu.org; Wed, 11 Mar 2009 04:32:31 -0400 Received: from dhcp-17-188.hq.eso.org ([134.171.17.188] helo=volta.aurel32.net) by hall.aurel32.net with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.69) (envelope-from ) id 1LhJrY-0008MW-Fx for qemu-devel@nongnu.org; Wed, 11 Mar 2009 09:32:29 +0100 Received: from aurel32 by volta.aurel32.net with local (Exim 4.69) (envelope-from ) id 1LhJrS-0005tP-WD for qemu-devel@nongnu.org; Wed, 11 Mar 2009 09:32:23 +0100 Date: Wed, 11 Mar 2009 09:32:22 +0100 From: Aurelien Jarno Subject: Re: [Qemu-devel] TCG/GCC breakage Message-ID: <20090311083222.GA21685@volta.aurel32.net> References: <5d6222a80903102040reef9775s8aaf9975e7594133@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <5d6222a80903102040reef9775s8aaf9975e7594133@mail.gmail.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On Wed, Mar 11, 2009 at 12:40:20AM -0300, Glauber Costa wrote: > I'm seeing a strange behaviour here using qemu-system-x86_64 > (kvm not even compiled in) on an i386 host > > I'm suspecting gcc is doing something nasty in here, but I'll open it > up here to see if any > of you have any suggestion. > > I get segfaults very early in execution, and after some investigation, > I figured out that > ebp register is corrupted. I can't determine where the corruption starts. Does QEMU segfault, or processes in the guest? How to reproduce that? Which QEMU version are you using? I am able to run a Debian Etch x86_64 guest without problem here. > I then did rm x86-64-softmmu/op_helper.o; make CC=gcc34, so only this > file get compiled > by an older gcc, and it worked again. Which versions of gcc did you tried? I am using gcc 4.3 here. > So it seems to me gcc may be generating gibberish somewhere in > helpers, but since > this code is a bit fragile, it might well be some mistake on our part. > > Ideas on how to attack it ? > You may want to use the -d option to find the offending helper function. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurelien@aurel32.net http://www.aurel32.net