From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58405) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fTRQq-0006dT-BY for qemu-devel@nongnu.org; Thu, 14 Jun 2018 08:32:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fTRQl-0008JV-CC for qemu-devel@nongnu.org; Thu, 14 Jun 2018 08:32:52 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:45960 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fTRQl-0008JA-6O for qemu-devel@nongnu.org; Thu, 14 Jun 2018 08:32:47 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 91BAF859A8 for ; Thu, 14 Jun 2018 12:32:46 +0000 (UTC) Date: Thu, 14 Jun 2018 14:32:41 +0200 From: Igor Mammedov Message-ID: <20180614143241.354dd8df@redhat.com> In-Reply-To: <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> <20180613170932.GA7451@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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: Eduardo Habkost Cc: "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" , Michal Privoznik , ldoktor@redhat.com, libvir-list@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, pbonzini@redhat.com, pkrempa@redhat.com On Wed, 13 Jun 2018 14:09:32 -0300 Eduardo Habkost wrote: > On Wed, Jun 13, 2018 at 03:23:09PM +0100, Daniel P. Berrang=C3=A9 wrote: > > On Wed, Jun 13, 2018 at 11:17:30AM -0300, Eduardo Habkost wrote: =20 > > > On Tue, Jun 12, 2018 at 01:50:33PM +0100, Daniel P. Berrang=C3=A9 wro= te: =20 > > > > On Tue, Jun 12, 2018 at 02:42:05PM +0200, Igor Mammedov wrote: =20 > > > > > 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 > > > >=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 FD > > > > 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 > > >=20 > > > So, what I'm really missing here is: do we have a good reason to > > > support --daemonize + --preconfig today? =20 > >=20 > > On the libvirt zero, I don't see a compelling need for it. =20 >=20 > Good. :) >=20 > > > The options I see are: > > > 1) complete daemonization before preconfig main loop =20 > [...] > > > 4) Not supporting -preconfig + -daemonize =20 > [...] > > > I believe the only reasonable options are (1) and (4). =20 > >=20 > > Agreed. =20 >=20 > If it was up to me, I would just go with (4) because it's > simpler. Let's just disable it for now. it will be easier to allow it than take it back later. >=20 > 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: >=20 > "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."