On Sun, Dec 14, 2008 at 01:15:42PM -0600, Anthony Liguori wrote: > Gleb Natapov wrote: > >On Sun, Dec 14, 2008 at 02:28:23PM +0200, Blue Swirl wrote: > > > >>On 12/14/08, Gleb Natapov <[email protected]> wrote: > >> > >>>There is a need for communication channel between host and various > >>> agents that are running inside a VM guest. The channel will be used > >>> for statistic gathering, logging, cut & paste, host screen resolution > >>> changes notification, guest configuration etc. > >>> > >>Isn't this exactly what the firmware configuration device was supposed > >>to be used for? In the list of use cases you gave, I don't see > >>anything that could not be done with it. > >> > >> > >The requirement for firmware configuration interface was different. We > >wanted something simple that we can use as early as possible in cpu init > >code and performance was not considered at all. Obviously PCI device > >doesn't > >fit for this. We don't want to write PCI driver inside a BIOS and PCI > >initialization is too late in HW initialization sequence. > > > >The requirement for vmchannel was that it should allow a guest > >to communicate with external (to qemu) process and with reasonable > >performance too. > > This is not a requirement that I think is important. It's only a > requirement for you because you have closed code that you want to > implement the backend with. I would personally be more interested in > vmchannel backends in QEMU and I think there will be a lot of them.
One non-QEMU backend I can see being implemented is a DBus daemon, providing a simple bus for RPC calls between guests & host. Or on a similar theme, perhaps a QPid message broker in the host OS. Yet another backend is a clustering service providing a virtual fence device to VMs. All of these would live outside QEMU, and as such exposing the backend using the character device infrastructure is a natural fit. Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
