From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Current KVM head crashes on startup Date: Wed, 18 Feb 2009 12:29:55 +0000 Message-ID: <499BFF43.4060105@redhat.com> References: <499AF81E.7080406@egenera.com> <20090218075126.GB12284@amit-x200.pnq.redhat.com> <20090218081602.GC12284@amit-x200.pnq.redhat.com> <499BCB9D.6070005@redhat.com> <20090218090540.GD12284@amit-x200.pnq.redhat.com> <499BE0C0.1040202@redhat.com> <20090218112128.GA4032@amit-x200.pnq.redhat.com> <499BF072.6080803@redhat.com> <20090218122016.GA5955@amit-x200.pnq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Anthony Liguori To: Amit Shah Return-path: Received: from mx2.redhat.com ([66.187.237.31]:57913 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752196AbZBRM3i (ORCPT ); Wed, 18 Feb 2009 07:29:38 -0500 In-Reply-To: <20090218122016.GA5955@amit-x200.pnq.redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Amit Shah wrote: >> I don't recall, it probably depends on whether frame pointers are used >> or not as well. >> > > As far as I know, kvm-userspace build arguments have remained the same > for quite some time. Also, we still pass the -g flag for userspace > compilations. > > Some distros change CFLAGS. >>> -- maintaining >>> specific code can introduce such regressions. >>> >>> >> That's a problem with assembly. x86 and x86_64 are different >> instruction sets. >> > > But the code in question isn't different on the two architectures. Just > a cpuid call that hasn't changed. > > The amount of available registers is different, as is the specification of which registers may be clobbered. > OK, given a patch to have just one version of the cpuid call, would you > be willing to take the risk of finding out which users it breaks for? > I'll send patches to revert and restore correct behaviour for 32-bit if > that does happen. > This is in upstream qemu so it's not my call but I wouldn't recommend breaking the build when a trivial one liner is possible. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.