From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35123) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGMI6-0007kj-76 for qemu-devel@nongnu.org; Fri, 24 Jun 2016 04:16:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bGMI4-00029Q-4p for qemu-devel@nongnu.org; Fri, 24 Jun 2016 04:16:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58827) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bGMI3-00029J-VT for qemu-devel@nongnu.org; Fri, 24 Jun 2016 04:16:40 -0400 References: <1456252389-4416-1-git-send-email-rth@twiddle.net> <1456252389-4416-6-git-send-email-rth@twiddle.net> <57607C9C.8070404@ilande.co.uk> <57631FC9.1040303@ilande.co.uk> <65a57d82-174f-cc1c-d613-984bffce13d3@twiddle.net> <03d5a05a-2674-b755-49d7-5a46dcadc237@redhat.com> From: Paolo Bonzini Message-ID: <26a800b0-5bfa-2218-235c-e10f78426126@redhat.com> Date: Fri, 24 Jun 2016 10:16:36 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PULL 5/8] target-sparc: Use global registers for the register window List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Richard Henderson , Mark Cave-Ayland , QEMU Developers On 24/06/2016 10:12, Peter Maydell wrote: > On 24 June 2016 at 07:36, Paolo Bonzini wrote: >> Mark, perhaps you can try to use migration to reduce the amount of >> logging? (Start QEMU with -snapshot, try to stop the vm before it >> fails. If you succeed, do a "migrate exec:cat>foo.sav" followed by >> "commit"; if you fail, try again). > > Why drag migration into it? I usually use 'savevm' and then > the -loadvm command line argument for this. (You need a > qcow2 disk image.) Well, migration and savevm are the same. :) In this case IIUC the failure happens from a CDROM so migration lets you avoid the qcow2 image. In general I find it easier to manage migration files on disk than saved snapshots. Paolo >> It would be nice to have a mechanism to stop the VM after executing N >> basic blocks. Binary search on this value then can help with coming up >> with a more easily debuggable snapshot, possibly to a point where the >> difference between pre-patch and post-patch becomes deterministic. > > You can use the monitor and an expect script to say "take a > snapshot 0.7 seconds into boot", which I've found to be > a good enough approximation: > > https://translatedcode.wordpress.com/2015/07/06/tricks-for-debugging-qemu-savevm-snapshots/ > > thanks > -- PMM >