From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:48034) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Rxf0f-0004bs-Ux for qemu-devel@nongnu.org; Wed, 15 Feb 2012 08:35:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Rxf0Z-0002ay-9c for qemu-devel@nongnu.org; Wed, 15 Feb 2012 08:35:01 -0500 Received: from goliath.siemens.de ([192.35.17.28]:24530) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Rxf0Y-0002aq-Mv for qemu-devel@nongnu.org; Wed, 15 Feb 2012 08:34:55 -0500 Message-ID: <4F3BB47C.5090304@siemens.com> Date: Wed, 15 Feb 2012 14:34:52 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <1328902266-25308-1-git-send-email-lcapitulino@redhat.com> <4F3B73DB.4010105@siemens.com> <20120215104954.1bce66da@doriath.home> In-Reply-To: <20120215104954.1bce66da@doriath.home> Content-Type: text/plain; charset=ISO-8859-1 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: Luiz Capitulino Cc: "aliguori@us.ibm.com" , "qemu-devel@nongnu.org" , "quintela@redhat.com" 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. ;) > > 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. Still, there would be monitor_get_fd and qmp_get_fd then not qemu_get_fd. I think that should be done already. BTW, where do you get the FDs from now in QMP mode? Is there currently a Monitor instance associated? Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux