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From: Gerd Hoffmann <kraxel@redhat.com>
To: Frank Yang <lfy@google.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Roman Kiryanov <rkir@google.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	virtio-dev@lists.oasis-open.org
Subject: Re: [virtio-dev] Memory sharing device
Date: Wed, 20 Feb 2019 07:51:52 +0100	[thread overview]
Message-ID: <20190220065152.44xv26wjtopkdnu2@sirius.home.kraxel.org> (raw)
In-Reply-To: <CAEkmjvXpAc1KZpYvfQa8jPzrh0MxpHNGPZ1LAH=5nQyRNCaTUw@mail.gmail.com>

  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.

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).

Non-linux systems obviously need something else for the job.  The
guest/host implementation details don't affect the virtio-gpu specs
though.

cheers,
  Gerd


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  reply	other threads:[~2019-02-20  6:52 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-01 20:34 [virtio-dev] Memory sharing device Roman Kiryanov
2019-02-04  5:40 ` Stefan Hajnoczi
2019-02-04 10:13   ` Gerd Hoffmann
2019-02-04 10:18     ` Roman Kiryanov
2019-02-05  7:42     ` Roman Kiryanov
2019-02-05 10:04       ` Dr. David Alan Gilbert
2019-02-05 15:17         ` Frank Yang
2019-02-05 15:21           ` Frank Yang
2019-02-05 21:06         ` Roman Kiryanov
2019-02-06  7:03           ` Gerd Hoffmann
2019-02-06 15:09             ` Frank Yang
2019-02-06 15:11               ` Frank Yang
2019-02-08  7:57               ` Stefan Hajnoczi
2019-02-08 14:46                 ` Frank Yang
2019-02-06 20:14           ` Dr. David Alan Gilbert
2019-02-06 20:27             ` Frank Yang
2019-02-07 12:10               ` Cornelia Huck
2019-02-11 14:49       ` Michael S. Tsirkin
2019-02-11 15:14         ` Frank Yang
2019-02-11 15:25           ` Frank Yang
2019-02-12 13:01             ` Michael S. Tsirkin
2019-02-12 13:16             ` Dr. David Alan Gilbert
2019-02-12 13:27               ` Michael S. Tsirkin
2019-02-12 16:17                 ` Frank Yang
2019-02-19  7:17                   ` Gerd Hoffmann
2019-02-19 15:59                     ` Frank Yang
2019-02-20  6:51                       ` Gerd Hoffmann [this message]
2019-02-20 15:31                         ` Frank Yang
2019-02-21  6:55                           ` Gerd Hoffmann
2019-02-19  7:12             ` Gerd Hoffmann
2019-02-19 16:02               ` Frank Yang
2019-02-20  7:02                 ` Gerd Hoffmann
2019-02-20 15:32                   ` Frank Yang
2019-02-21  7:29                     ` Gerd Hoffmann
2019-02-21  9:24                       ` Dr. David Alan Gilbert
2019-02-21  9:59                         ` Gerd Hoffmann
2019-02-21 10:03                           ` Dr. David Alan Gilbert
2019-02-22  6:15                           ` Michael S. Tsirkin
2019-02-22  6:42                             ` Gerd Hoffmann
2019-02-11 16:57           ` Michael S. Tsirkin
2019-02-12  8:27         ` Roman Kiryanov
2019-02-12 11:25           ` Dr. David Alan Gilbert
2019-02-12 13:47             ` Cornelia Huck
2019-02-12 14:03               ` Michael S. Tsirkin
2019-02-12 15:56                 ` Frank Yang
2019-02-12 16:46                   ` Dr. David Alan Gilbert
2019-02-12 17:20                     ` Frank Yang
2019-02-12 17:26                       ` Frank Yang
2019-02-12 19:06                         ` Michael S. Tsirkin
2019-02-13  2:50                           ` Frank Yang
2019-02-13  4:02                             ` Michael S. Tsirkin
2019-02-13  4:19                               ` Michael S. Tsirkin
2019-02-13  4:59                                 ` Frank Yang
2019-02-13 18:18                                   ` Frank Yang
2019-02-14  7:15                                     ` Frank Yang
2019-02-22 22:05                                       ` Michael S. Tsirkin
2019-02-24 21:19                                         ` Frank Yang
2019-02-13  4:59                               ` Frank Yang
2019-02-19  7:54                       ` Gerd Hoffmann
2019-02-19 15:54                         ` Frank Yang
2019-02-20  3:46                           ` Michael S. Tsirkin
2019-02-20 15:24                             ` Frank Yang
2019-02-20 19:29                               ` Michael S. Tsirkin
2019-02-20  6:25                           ` Gerd Hoffmann
2019-02-20 15:30                             ` Frank Yang
2019-02-20 15:35                               ` Frank Yang
2019-02-21  6:44                               ` Gerd Hoffmann
2019-02-12 18:22                   ` Michael S. Tsirkin
2019-02-12 19:01                     ` Frank Yang
2019-02-12 19:15                       ` Michael S. Tsirkin
2019-02-12 20:15                         ` Frank Yang
2019-02-12 13:00           ` Michael S. Tsirkin

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