On Tue, Feb 19, 2019 at 10:52 PM Gerd Hoffmann <kra...@redhat.com> wrote:
> Hi, > > > However, dma-buf seems to require either a Linux kernel or a Linux host. > > Sure. They allow passing buffers from one linux driver to another > without copying the data. > > > Dma-bufs aren't also 1:1 with Vulkan host visible memory pointers, > > or v4l2 codec buffers, or ffmpeg codec buffers, etc. > > Some v4l2 drivers have dma-buf support, so you can pass buffers from > v4l2 to (for example) gpu drivers that way. > > > The proposed device would be able to expose memory for direct access in a > > way that > > does not couple to dma-buf which is highly desirable for our use case. > > Using the ping/event messages, even win32 handles and general opaque fds > > can be passed from host to guest and back. > > > > You can think of the proposed device as a 'virtio-dmabuf' that > > tries to expose shareable memory in a way that disregards implementation > > details of > > guest and host kernels. > > That would probably look alot like virtio-gpu with only the resource > handling. virtio-gpu fundamentally are just buffers. > > This plus new transport makes me wonder if we can have something like a transport/device pair where the transport makes it easy to work directly off host memory pci bar, and the device is virtio-gpu except really just buffers. We'd really like to go for something like this. Also virtio-dmabuf would be a pretty bad name. dma-bufs are not a > virtio concept, they are a linux concept. They can be used by linux > guests, to pass buffers from/to virtio-gpu (note: I'm still busy adding > driver support for that). They can be used by linux hosts, to pass > buffers (with udmabuf help) from qemu to other processes/devices > (details are still to be hashed out). > > Got it, that sounds pretty interesting. > Non-linux systems obviously need something else for the job. The > guest/host implementation details don't affect the virtio-gpu specs > though. While we're talking about this: what is your plan for virtio-gpu implementations for non-Linux guests/hosts? > > cheers, > Gerd > >
