On Wed, Dec 23, 2009 at 09:09:21AM -0600, Anthony Liguori wrote: > On 12/23/2009 12:15 AM, Kyle Moffett wrote: > > This is actually something that is of particular interest to me. I > > have a few prototype boards right now with programmable PCI-E > > host/device links on them; one of my long-term plans is to finagle > > vbus into providing multiple "virtual" devices across that single > > PCI-E interface. > > > > Specifically, I want to be able to provide virtual NIC(s), serial > > ports and serial consoles, virtual block storage, and possibly other > > kinds of interfaces. My big problem with existing virtio right now > > (although I would be happy to be proven wrong) is that it seems to > > need some sort of out-of-band communication channel for setting up > > devices, not to mention it seems to need one PCI device per virtual > > device. > > We've been thinking about doing a virtio-over-IP mechanism such that you > could remote the entire virtio bus to a separate physical machine. > virtio-over-IB is probably more interesting since you can make use of > RDMA. virtio-over-PCI-e would work just as well. > I didn't know you were interested in this as well. See my later reply to Kyle for a lot of code that I've written with this in mind. > virtio is a layered architecture. Device enumeration/discovery sits at > a lower level than the actual device ABIs. The device ABIs are > implemented on top of a bulk data transfer API. The reason for this > layering is so that we can reuse PCI as an enumeration/discovery > mechanism. This tremendenously simplifies porting drivers to other OSes > and let's us use PCI hotplug automatically. We get integration into all > the fancy userspace hotplug support for free. > > But both virtio-lguest and virtio-s390 use in-band enumeration and > discovery since they do not have support for PCI on either platform. > I'm interested in the same thing, just over PCI. The only PCI agent systems I've used are not capable of manipulating the PCI configuration space in such a way that virtio-pci is usable on them. This means creating your own enumeration mechanism. Which sucks. See my virtio-phys code (http://www.mmarray.org/~iws/virtio-phys/) for an example of how I did it. It was modeled on lguest. Help is appreciated. Ira -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
