From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50247) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1acskp-0002ek-R4 for qemu-devel@nongnu.org; Mon, 07 Mar 2016 05:51:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1acskl-0005eb-QR for qemu-devel@nongnu.org; Mon, 07 Mar 2016 05:51:11 -0500 Received: from smtp.citrix.com ([66.165.176.89]:2354) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1acskl-0005eH-Ly for qemu-devel@nongnu.org; Mon, 07 Mar 2016 05:51:07 -0500 Date: Mon, 7 Mar 2016 10:51:07 +0000 From: Wei Liu Message-ID: <20160307105107.GA31271@citrix.com> References: <20160212191037.GF8818@citrix.com> <3fbbf2a606a14f708655037f5e4fb31e@AMSPEX02CL03.citrite.net> <20160215131621.GL8818@citrix.com> <56C1D391.101@suse.com> <20160215134409.GM8818@citrix.com> <56DD2C0A.5050509@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <56DD2C0A.5050509@suse.com> Subject: Re: [Qemu-devel] [Xen-devel] RFC: configuring QEMU virtfs for Xen PV(H) guests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juergen Gross Cc: Wei Liu , "qemu-devel@nongnu.org" , Paul Durrant , Stefano Stabellini , "aneesh.kumar@linux.vnet.ibm.com" , Anthony Perard , Xen-devel , "gkurz@linux.vnet.ibm.com" On Mon, Mar 07, 2016 at 08:21:46AM +0100, Juergen Gross wrote: > Hi Wei, > > On 15/02/16 14:44, Wei Liu wrote: > > On Mon, Feb 15, 2016 at 02:33:05PM +0100, Juergen Gross wrote: > >> On 15/02/16 14:16, Wei Liu wrote: > >>> On Mon, Feb 15, 2016 at 09:07:13AM +0000, Paul Durrant wrote: > >>>>> > >>> [...] > >>>>> # Option 2: Invent a xen-9p device > >>>>> > >>>>> Another way of doing it is to expose a dummy xen-9p device, so that we > >>>>> can use -fsdev XXX -device xen-9p,YYY. This simple device should be > >>>>> used to capture the parameters like mount_tag and fsdev_id, and then > >>>>> chained itself to a known location. Later Xen transport can traverse > >>>>> this known location. This xen-9p device doesn't seem to fit well into > >>>>> the hierarchy. The best I can think of its parent should be > >>>>> TYPE_DEVICE. In this case: > >>>>> > >>>>> 1. Toolstack arranges some xenstore entries. > >>>>> 2. Toolstack arranges command line options for QEMU: > >>>>> -fsdev XXX -device xen-9p,XXX > >>>>> 3. QEMU starts up in xen-attach mode, scans xenstore for relevant > >>>>> entries, then traverses the known location. > >>>>> > >>>>> Downside: Inventing a dummy device looks suboptimal to me. > >> > >> Sorry, didn't notice this thread before. > >> > > > > No need to be sorry. I posted this last Friday night. I wouldn't expect > > many replies on Monady. > > > >> For Xen pvUSB backend in qemu I need a Xen system device acting as > >> parent for being able to attach/detach virtual USB busses. > >> > >> I haven't had time to update my patches for some time, but the patch > >> for this system device is rather easy. It could be used as a parent > >> of the xen-9p devices, too. > >> > >> I've attached the patch for reference. > >> > > > > Thanks. I will have a look at your patch. > > Did you have some time to look at the patch? I'm asking because I > finally found some time to start working on V2 of my qemu based pvUSB > backend. Stefano asked me to hide the system device in my backend and > I want to avoid that in case you are needing it, too. > Yes. I need this device. I'm not sure what "hiding this device in backend" means though. Wei. > Juergen