From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?Um9nZXIgUGF1IE1vbm7DqQ==?= Subject: Re: libxl: hotplug scripts and backend_domid != 0 Date: Wed, 10 Apr 2013 13:22:30 +0200 Message-ID: <51654B76.8020606@citrix.com> References: <515DA023.70107@invisiblethingslab.com> <1365592473.26448.31.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1365592473.26448.31.camel@zakaz.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell Cc: George Dunlap , Marek Marczykowski , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 10/04/13 13:14, Ian Campbell wrote: > On Thu, 2013-04-04 at 16:45 +0100, Marek Marczykowski wrote: >> Hi, >> >> Currently when using backend outside of dom0 (for at least one device) libxl >> force udev call method of hotplug scripts for entire system. > > Roger, do you remember why? Was it just because this change was > relatively late in the 4.2 cycle and we were being conservative? > >> Maybe this can be >> changed to: >> a) if backend_domid==0, proceed according to run_hotplug_scipts >> b) if backend_domid!=0, ignore run_hotplug_scipts and always use udev >> ? >> >> Does it sound sensible? > > It does, although we are now relatively late in the 4.3 cycle so I'm not > sure it would be appropriate. George? > > I think Roger is intending to implement a new scheme for driver domains > etc in 4.4, which may make this particular issue disappear anyway. Since run_hotplug_scripts is a global variable, not per-device, changing it when backend_domid != 0 for a certain device might cause trouble to other devices, or guests launched concurrently. Also udev scripts check run_hotplug_scripts in xenstore, so changing it while there are guests being created or destroyed might also cause trouble.