From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:45826) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TsKw7-0000hD-D5 for qemu-devel@nongnu.org; Mon, 07 Jan 2013 17:12:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TsKw4-0006gx-Ra for qemu-devel@nongnu.org; Mon, 07 Jan 2013 17:12:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38529) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TsKw4-0006gn-Jh for qemu-devel@nongnu.org; Mon, 07 Jan 2013 17:12:48 -0500 Date: Tue, 8 Jan 2013 00:16:31 +0200 From: "Michael S. Tsirkin" Message-ID: <20130107221631.GD11305@redhat.com> References: <1354887155-32281-1-git-send-email-fred.konrad@greensocs.com> <20121217154508.GA28712@redhat.com> <20121218110153.GC22586@redhat.com> <50D053CC.9040203@greensocs.com> <20121218132152.GB26110@redhat.com> <87vcb8g3bs.fsf@codemonkey.ws> <20130107205950.GD10575@redhat.com> <878v841ybl.fsf@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <878v841ybl.fsf@codemonkey.ws> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [RFC PATCH v6 0/6] Virtio refactoring. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Peter Maydell , e.voevodin@samsung.com, mark.burton@greensocs.com, qemu-devel@nongnu.org, stefanha@redhat.com, cornelia.huck@de.ibm.com, afaerber@suse.de, KONRAD =?iso-8859-1?Q?Fr=E9d=E9ric?= On Mon, Jan 07, 2013 at 03:24:14PM -0600, Anthony Liguori wrote: > "Michael S. Tsirkin" writes: >=20 > > On Mon, Jan 07, 2013 at 02:12:23PM -0600, Anthony Liguori wrote: > >> "Michael S. Tsirkin" writes: > >>=20 > >> > On Tue, Dec 18, 2012 at 12:30:20PM +0100, KONRAD Fr=E9d=E9ric wrot= e: > >> >> On 18/12/2012 12:01, Michael S. Tsirkin wrote: > >> >> >On Tue, Dec 18, 2012 at 10:33:37AM +0000, Peter Maydell wrote: > >> >> >>On 17 December 2012 15:45, Michael S. Tsirkin = wrote: > >> >> >>>Is the point to allow virtio-mmio? Why can't virtio-mmio be j= ust > >> >> >>>another bus, like a pci bus, and another binding, like the vir= tio-pci > >> >> >>>binding? > >> >> >>(a) the current code is really not very nice because it's not > >> >> >>actually a proper set of QOM/qdev devices > >> >> >>(b) unlike PCI, you can't create sysbus devices on the > >> >> >>command line, because they don't correspond to a user > >> >> >>pluggable bit of hardware. We don't want users to have to know > >> >> >>an address and IRQ number for each virtio-mmio device (especial= ly > >> >> >>since these are board specific); instead the board can create > >> >> >>and wire up transport devices wherever is suitable, and the > >> >> >>user just creates the backend (which is plugged into the virtio= bus). > >> >> >> > >> >> >>-- PMM > >> >> >This is what I am saying: create your own bus and put > >> >> >your devices there. Allocate resources when you init > >> >> >a device. > >> >> > > >> >> >Instead you seem to want to expose a virtio device as two device= s to > >> >> >user - if true this is not reasonable. > >> >> > > >> >> The modifications will be transparent to the user, as we will kee= p > >> >> virtio-x-pci devices. > >> > > >> > So there are three ways to add virtio pci devices now. > >> > Legacy -device virtio-net-pci, legacy legacy -net nic.model=3Dvirt= io > >> > and the new one with two devices. > >> > If yes it's not transparent, it's user visible. > >> > Or did I misunderstand? > >> > > >> > Look we can have a virtio network device on a PCI bus. > >> > A very similar device can be created on XXX bus, and > >> > we can and do share a lot of code. > >> > This makes it two devices? Why not 4? > >> > One for TX one for RX one for control one for PCI. > >> > I hope I'm not giving anyone ideas ... > >>=20 > >> Devices !=3D things users need to worry about. > >>=20 > >> The documented way to create network devices is completely different > >> than any possible syntax you can conjure up with -device. > >>=20 > >> Really, -device is not something users should have to deal with--eve= r. > >> It's a low level API, not a UI. > >>=20 > >> Regards, > >>=20 > >> Anthony Liguori > > > > Interesting. > > Let's assume I want to put a device behind a pci bridge > > (for example I want more than 32 of these). >=20 > You don't want to put a device behind a PCI bridge, you want to have > more than 32 devices. >=20 > '-net nic' should do the Right Thing when presented with more than 32 > devices. >=20 > > It's impossible without -device, isn't it? >=20 > Think of -device like an API and -net as our UI. Wait a second, -net implies vlans no? And this means no offloads so performance suffers ... > Management tools want > to use an API, because it provides low level control and generally has > limited side effects. >=20 > Users want a UI that makes sense. Trying to make both things satisfy > both audiences will almost certainly fail. >=20 > If a common use case cannot be done without resorting to using our API, > then we ought to improve our UI. >=20 > Regards, >=20 > Anthony Liguori >=20 > > > >> > > >> > --=20 > >> > MST