From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48659) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YyHyq-0003qI-H9 for qemu-devel@nongnu.org; Fri, 29 May 2015 06:57:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YyHyp-0000D1-JV for qemu-devel@nongnu.org; Fri, 29 May 2015 06:57:36 -0400 Date: Fri, 29 May 2015 11:57:26 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20150529105725.GF2127@work-vm> References: <1432214378-31891-4-git-send-email-kwolf@redhat.com> <555E5462.7040702@redhat.com> <20150528172922.GF2127@work-vm> <87wpzrn7px.fsf@blackfin.pond.sub.org> <20150529083309.GB2127@work-vm> <20150529091126.GC3804@noname.redhat.com> <20150529093808.GD2127@work-vm> <20150529102752.GD3804@noname.redhat.com> <20150529103432.GE2127@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH v2 3/8] fdc: Introduce fdctrl->phase List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Kevin Wolf , John Snow , Markus Armbruster , qemu-block@nongnu.org, QEMU Developers * Peter Maydell (peter.maydell@linaro.org) wrote: > On 29 May 2015 at 11:34, Dr. David Alan Gilbert wrote: > > It's the destination I'm worried about here, not the source; lets say > > you have two devices, a & b. 'a' gets serialised, but then 'b' finds > > it has to wait, so we return to running the source and sending pages > > across. However the destination has already loaded the 'a' device state; > > so that when we serialise again we send a new 'a' device state'; I'm > > worrying here that the destination 'a' state loader would get upset > > trying to load the same state twice without somehow resetting it. > > You would need to reset the system before resending device state, > I think. Device implementations rely on knowing that migration happens > into a freshly reset device, and we don't have any way of resetting > a single device, only the whole system at once. I don't think you can do a device (or certainly not a system) reset without resending the contents of RAM which was the whole point of not restarting the migration from the beginning. Dave > > -- PMM -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK