"Michael S. Tsirkin" <m...@redhat.com> writes: > On Mon, Jan 07, 2013 at 02:12:23PM -0600, Anthony Liguori wrote: >> "Michael S. Tsirkin" <m...@redhat.com> writes: >> >> > On Tue, Dec 18, 2012 at 12:30:20PM +0100, KONRAD Frédéric wrote: >> >> 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 <m...@redhat.com> wrote: >> >> >>>Is the point to allow virtio-mmio? Why can't virtio-mmio be just >> >> >>>another bus, like a pci bus, and another binding, like the virtio-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 (especially >> >> >>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 devices to >> >> >user - if true this is not reasonable. >> >> > >> >> The modifications will be transparent to the user, as we will keep >> >> 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=virtio >> > 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 ... >> >> Devices != things users need to worry about. >> >> The documented way to create network devices is completely different >> than any possible syntax you can conjure up with -device. >> >> Really, -device is not something users should have to deal with--ever. >> It's a low level API, not a UI. >> >> Regards, >> >> 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).
You don't want to put a device behind a PCI bridge, you want to have more than 32 devices. '-net nic' should do the Right Thing when presented with more than 32 devices. > It's impossible without -device, isn't it? Think of -device like an API and -net as our UI. Management tools want to use an API, because it provides low level control and generally has limited side effects. Users want a UI that makes sense. Trying to make both things satisfy both audiences will almost certainly fail. If a common use case cannot be done without resorting to using our API, then we ought to improve our UI. Regards, Anthony Liguori > >> > >> > -- >> > MST
