From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41638) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WYosV-0000Ea-1j for qemu-devel@nongnu.org; Fri, 11 Apr 2014 23:45:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WYosN-0002Bx-II for qemu-devel@nongnu.org; Fri, 11 Apr 2014 23:45:14 -0400 Received: from mail-pd0-f176.google.com ([209.85.192.176]:49278) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WYosN-0002B5-Cz for qemu-devel@nongnu.org; Fri, 11 Apr 2014 23:45:07 -0400 Received: by mail-pd0-f176.google.com with SMTP id r10so5994756pdi.7 for ; Fri, 11 Apr 2014 20:45:05 -0700 (PDT) Message-ID: <5348B6BB.1080503@ozlabs.ru> Date: Sat, 12 Apr 2014 13:44:59 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 References: <1396530891-6352-1-git-send-email-aik@ozlabs.ru> <1396530891-6352-5-git-send-email-aik@ozlabs.ru> <53468FBD.6040906@suse.de> <5346AB55.8030807@ozlabs.ru> <5347B892.5010107@suse.de> <1397253344.31160.14.camel@pasglop> In-Reply-To: <1397253344.31160.14.camel@pasglop> Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 4/4] spapr: Add support for time base offset migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Benjamin Herrenschmidt , Alexander Graf Cc: Paul Mackerras , qemu-ppc , qemu-devel@nongnu.org On 04/12/2014 07:55 AM, Benjamin Herrenschmidt wrote: > On Fri, 2014-04-11 at 11:40 +0200, Alexander Graf wrote: >>> And G5 uses 33333333. I really do not understand why it is bad to >>> send-and-check timer frequency. Why? >> >> Because the guest will continue to run at a different TB frequency on >> the new host and break. > > Right, which is why we should send it accross so it can be checked and > we can barf accordingly rather than having random odd things happen :-) As I was explained several times already, QEMU does not transfer configuration (yet) and we only should implement correct transfer of parameters (without checking) and specify in the QEMU command line the ones which cannot be transferred. So with timebase frequency, it should be a command line switch (-machine option?) which would take frequency and fail if it is POWER7/8 and not 500MHz. And then libvirt should take care of it (always pass it or have XML tag for it). Same story as with migrating IRQs (which I do now in a hacky way but I am going to changed it to work via the command line). -- Alexey