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Subject: Re: [Qemu-devel] [PATCH] *** Vhost-pci RFC v2 ***
On 08/31/2016 08:30 PM, Marc-André Lureau wrote:
Hi Marc-André, thanks for joining the reviewing process :)
Yes. A part of the patch is for the virtio spec. I will separate the patches (please see the next response).
I have the qemu-devel and virtio mailinglist kept here.
Agree. I will separate the device spec description from the protocol description. The device description will be made a virtio spec patch, and the protocol description will be made a qemu patch to doc/specs.
Not really. A virtio device has it own driver (e.g. a virtio-net driver for a virtio-net device). A vhost-pci device plays the role of a backend (just like vhost_net, vhost_user) for a virtio device. If we use the "device/driver" naming convention, the vhost-pci device is part of the "device". But I actually prefer to use "frontend/backend" :) If we check the QEMU's doc/specs/vhost-user.txt, it also uses "backend" to describe.
Right. We recently changed the plan - trying to make it (the vhost-pci protocol) an extension of the vhost-user protocol.
We call it "multiple backend functionalities" (e.g. vhost-pci-net, vhost-pci-scsi..). A vhost-pci driver contains multiple such backend functionalities, because in this way they can reuse (share) the same memory mapping. To be more precise, a vhost-pci device supplies the memory of a frontend VM, and all the backend functionalities need to access the same frontend VM memory, so we consolidate them into one vhost-pci driver to use one vhost-pci device.
Yes. But I think it's also possible to add the interrupt support. For example, we can use ioeventfd (or hypercall) to inject interrupts to the fontend VM after transmitting packets.
Probably in October (next month). I think it also depends on the discussions here :)