From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Hajnoczi Subject: Re: KVM git hangs with if=virtio (works under kvm 0.12.3) Date: Mon, 5 Jul 2010 13:11:25 +0100 Message-ID: References: <1278041518.10459.48.camel@geektop> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: kvm@vger.kernel.org To: ewheeler Return-path: Received: from mail-vw0-f46.google.com ([209.85.212.46]:41460 "EHLO mail-vw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752021Ab0GEML0 convert rfc822-to-8bit (ORCPT ); Mon, 5 Jul 2010 08:11:26 -0400 Received: by vws5 with SMTP id 5so5962979vws.19 for ; Mon, 05 Jul 2010 05:11:26 -0700 (PDT) In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Jul 2, 2010 at 9:07 AM, Stefan Hajnoczi wr= ote: > On Fri, Jul 2, 2010 at 4:31 AM, ewheeler wrote: >> Hello all, >> >> I'm booting a CentOS kernel under today's KVM git and it hangs after >> initializing the serial port when the drive if=3Dvirtio, but not whe= n >> drive if=3Dide. =A0Look close---this is not a "forgot to add virtio_= blk" >> problem. =A0If I use 0.12.3 from Ubuntu 10.04 it works properly. >> >> Reproduction: >> >> Using kvm 0.12.3 on ubuntu 10.04 (1:84+dfsg-0ubuntu16+0.12.3+noroms >> +0ubuntu9) it will work properly: >> >> =A0qemu-system-x86_64 -drive file=3Ddummy-disk-image,if=3Dvirtio \ >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0-kernel vmlinuz-2.6.1= 8-194.3.1.el5.centos.plus >> >> As expected, the kernel panics unable to mount root (good-boot.png). >> This makes sense, as "dummy-disk-image" is 1MB of 0x00 bytes. >> >> ---However---if I use today's git (2010-07-01) of kvm: >> >> =A0 /usr/local/kvm-git/bin/qemu-system-x86_64 -drive file=3Ddummy-di= sk-image,if=3Dvirtio \ >> =A0 =A0 =A0 =A0-kernel vmlinuz-2.6.18-194.3.1.el5.centos.plus >> >> This hangs just after initializing the Serial device (obtained by ad= ding >> -serial stdio -append console=3DttyS0): >> >> Note that this only happens with the disk interface set to virtio >> (if=3Dvirtio). =A0It works fine for ide (if=3Dide). >> >> >> Am I doing something wrong here? >> Is anyone else having this problem? > > I have seen this issue with a RHEL 5.5 guest running under > qemu-kvm.git. =A0It boots a new guest fine but hangs as you described > with the RHEL 5.5 kernel. =A0I have not investigated. This issue is affected by extboot, a feature that enables booting from virtio-blk devices. I have just sent a patch to the KVM mailing list to restore extboot functionality which has been broken in qemu-kvm.git. That patch can be used to work around this issue by using "-drive ...,boot=3Don" but it doesn't explain why the RHEL 5.5 kernel hangs during serial initialization when extboot is not present. Stefan