From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35942) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fT9HC-0003lS-PQ for qemu-devel@nongnu.org; Wed, 13 Jun 2018 13:09:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fT9H9-00060y-Go for qemu-devel@nongnu.org; Wed, 13 Jun 2018 13:09:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40382) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fT9H9-0005zR-A5 for qemu-devel@nongnu.org; Wed, 13 Jun 2018 13:09:39 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9B0F3307D873 for ; Wed, 13 Jun 2018 17:09:38 +0000 (UTC) Date: Wed, 13 Jun 2018 14:09:32 -0300 From: Eduardo Habkost Message-ID: <20180613170932.GA7451@localhost.localdomain> References: <20180608132105.GA24764@localhost.localdomain> <20180611151625.4b2420b8@redhat.com> <20180611190607.GU7451@localhost.localdomain> <20180611232924.6e04b6f8@igors-macbook-pro.local> <20180611223633.GG7451@localhost.localdomain> <5cef972d-250b-5464-7482-90fa24d36c80@redhat.com> <20180612144205.2169e7a2@redhat.com> <20180612125033.GF24690@redhat.com> <20180613141730.GR7451@localhost.localdomain> <20180613142309.GX19901@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20180613142309.GX19901@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [libvirt] [PATCH v6 2/2] vl: fix use of --daemonize with --preconfig List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Cc: Igor Mammedov , Michal Privoznik , ldoktor@redhat.com, libvir-list@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, pbonzini@redhat.com, pkrempa@redhat.com On Wed, Jun 13, 2018 at 03:23:09PM +0100, Daniel P. Berrang=E9 wrote: > On Wed, Jun 13, 2018 at 11:17:30AM -0300, Eduardo Habkost wrote: > > On Tue, Jun 12, 2018 at 01:50:33PM +0100, Daniel P. Berrang=E9 wrote: > > > On Tue, Jun 12, 2018 at 02:42:05PM +0200, Igor Mammedov wrote: > > > > We can keep daemonizing flow in QEMU as it's now. > > > > But Eduardo's idea about libvirt created socked + letting QEMU co= nnect to it > > > > has a merit. It should fix current deadlock issue with as monitor > > > > won't be depending on lead exit event. > > >=20 > > > NB, libvirt only ever uses --daemonize when probing capabilities, n= ever > > > when launching QEMU for a real VM. In the latter case, we now use F= D > > > passing, so libvirt opens the UNIX domain socket listener, and pass= es > > > this into QEMU. So libvirt knows it can connect to the listener > > > immediately and will only ever get a failure if QEMU has exited. > >=20 > > So, what I'm really missing here is: do we have a good reason to > > support --daemonize + --preconfig today? >=20 > On the libvirt zero, I don't see a compelling need for it. Good. :) > > The options I see are: > > 1) complete daemonization before preconfig main loop [...] > > 4) Not supporting -preconfig + -daemonize [...] > > I believe the only reasonable options are (1) and (4). >=20 > Agreed. If it was up to me, I would just go with (4) because it's simpler. But if somebody wants to implement (1), the caveats should be clearly documented. I would prefer to simply document "--daemonize --preconfig" as experimental, with something like: "Note: usage of --daemonize with the --preconfig option is experimental, because it can prevent QEMU from reporting machine initialization errors and prevent some features from working after QEMU is daemonized." --=20 Eduardo