From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:35345) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Rxiz7-0005AB-FR for qemu-devel@nongnu.org; Wed, 15 Feb 2012 12:49:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Rxiz2-00025j-Sl for qemu-devel@nongnu.org; Wed, 15 Feb 2012 12:49:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:18049) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Rxiz2-00025d-JL for qemu-devel@nongnu.org; Wed, 15 Feb 2012 12:49:36 -0500 Date: Wed, 15 Feb 2012 15:49:31 -0200 From: Luiz Capitulino Message-ID: <20120215154931.5253ffae@doriath.home> In-Reply-To: <4F3BEDD3.5070307@siemens.com> References: <1328902266-25308-1-git-send-email-lcapitulino@redhat.com> <4F3B73DB.4010105@siemens.com> <20120215104954.1bce66da@doriath.home> <4F3BB47C.5090304@siemens.com> <20120215152333.1beb96b1@doriath.home> <4F3BEDD3.5070307@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/6] qapi: Convert migrate List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: "aliguori@us.ibm.com" , "qemu-devel@nongnu.org" , "quintela@redhat.com" On Wed, 15 Feb 2012 18:39:31 +0100 Jan Kiszka wrote: > On 2012-02-15 18:23, Luiz Capitulino wrote: > > On Wed, 15 Feb 2012 14:34:52 +0100 > > Jan Kiszka wrote: > > > >> On 2012-02-15 13:49, Luiz Capitulino wrote: > >>> On Wed, 15 Feb 2012 09:59:07 +0100 > >>> Jan Kiszka wrote: > >>> > >>>> On 2012-02-10 20:31, Luiz Capitulino wrote: > >>>>> This is a rebase of Anthony's conversion, from his glib branch; and this is > >>>>> also the beginning of the conversion of complex commands to the qapi. > >>>>> > >>>>> There are two important changes that should be observed: > >>>>> > >>>>> 1. patch 5/6 purges the 'mon' object from migration code. One of the > >>>>> consequences is that we lose the ability to print progress status to > >>>>> the HMP user (esp. in block migration) > >>>> > >>>> This smells extremely fishy. You have some common "monitor" context in > >>>> both cases, means something that decides where suspend/resume takes > >>>> effect or where to pick up file descriptors from. If the exiting Monitor > >>>> object is not generic enough, introduce some super-class and use that in > >>>> common services. Or make sure that a variant of Monitor is also valid > >>>> over QMP. But don't remove the dependency from the API, while > >>>> reintroducing it via the backdoor of cur_mon. > >>> > >>> What we really want to do here is to untangle HMP and QMP. Unfortunately, > >>> the migrate command is one of those commands where the two are deeply > >>> tangled and the split won't be perfect. > >>> > >>> However, the two cases you mention above are solvable: > >>> > >>> 1. suspend/resume: this is *really* a HMP feature and shouldn't be in any > >>> QMP code path. This is correctly addressed in this series by moving it > >>> to hmp_migrate() > >> > >> Almost correctly. ;) > > > > Well, it was moved to the right place :) > > (see the other thread) Yeah, I saw it and will fix the problems you've pointed out. > >>> 2. file descriptor passing: the new QMP server will support sessions and > >>> we'll move statefull commands (like getfd) to it. When we do it, we'll > >>> introduce a new API to get fds that won't depend on the monitor. However, > >>> this requires all commands to be converted to the qapi first. Meanwhile > >>> we use the qemu_get_fd() API. > >>> > >>> Note: qemu_get_fd() is temporary, it shouldn't be a problem to use it > >>> (if it's not incorrect, of course, I honestly haven't fully tested it yet). > >> > >> So there will be a common super-class of Monitor and that new QMP > >> session that also manages the file descriptors? That would make sense. > > > > Oh, yes. Now I see that you said exactly that earlier. Sorry for more or less > > re-stating it. > > > >> Still, there would be monitor_get_fd and qmp_get_fd then not > >> qemu_get_fd. I think that should be done already. > > > > The problem is that monitor_get_fd() already exists and qmp_get_fd() > > doesn't make much sense (as this is not related to QMP right now). So, > > I could call it monitor_get_fd_cur() or something like this. > > What object represent a QMP session now? We don't exactly have the notion of a QMP session today, but all QMP state is currently stored in the Monitor object. > That object will once hold the > reference to the FDs. So some qmp_get_fd will take that session and > return the requested fd - so, it does make sense, long-term at least. Yes. Actually most of the code has already been written by Anthony: git://repo.or.cz/qemu/aliguori.git glib (look at qmp-core.c) What I'm doing is to rebase it, do some integration work & fix ups. > In any case, as long as everyone can mess with cur_mon, you don't need > to introduce wrappers that just link a normal monitor service with that > variable. So, you're suggestion to just use monitor_get_fd(), right?