From: Gerd Hoffmann <kraxel@redhat.com>
To: David Stevens <stevensd@chromium.org>
Cc: "Dylan Reid" <dgreid@chromium.org>,
"Tomasz Figa" <tfiga@chromium.org>,
"Zach Reizner" <zachr@chromium.org>,
"Geoffrey McRae" <geoff@hostfission.com>,
"Keiichi Watanabe" <keiichiw@chromium.org>,
"Dmitry Morozov" <dmitry.morozov@opensynergy.com>,
"Alexandre Courbot" <acourbot@chromium.org>,
"Alex Lau" <alexlau@chromium.org>,
"Stéphane Marchesin" <marcheu@chromium.org>,
"Pawel Osciak" <posciak@chromium.org>,
"Hans Verkuil" <hverkuil@xs4all.nl>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Gurchetan Singh" <gurchetansingh@chromium.org>,
"Linux Media Mailing List" <linux-media@vger.kernel.org>,
virtio-dev@lists.oasis-open.org,
qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [virtio-dev] Re: guest / host buffer sharing ...
Date: Mon, 16 Dec 2019 14:47:28 +0100 [thread overview]
Message-ID: <20191216134728.czulyb6yvrkokrqv@sirius.home.kraxel.org> (raw)
In-Reply-To: <CAD=HUj623MyeZ7VmrYTfig9oiyNhipidpvhuuurs3VgGBgjZpQ@mail.gmail.com>
Hi,
> > Of course only virtio drivers would try step (2), other drivers (when
> > sharing buffers between intel gvt device and virtio-gpu for example)
> > would go straight to (3).
>
> For virtio-gpu as it is today, it's not clear to me that they're
> equivalent. As I read it, the virtio-gpu spec makes a distinction
> between the guest memory and the host resource. If virtio-gpu is
> communicating with non-virtio devices, then obviously you'd just be
> working with guest memory. But if it's communicating with another
> virtio device, then there are potentially distinct guest and host
> buffers that could be used. The spec shouldn't leave any room for
> ambiguity as to how this distinction is handled.
Yep. It should be the host side buffer. The whole point is to avoid
the round trip through the guest after all. Or does someone see a
useful use case for the guest buffer? If so we might have to add some
way to explicitly specify whenever we want the guest or host buffer.
cheers,
Gerd
next prev parent reply other threads:[~2019-12-16 13:47 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 10:54 guest / host buffer sharing Gerd Hoffmann
2019-11-05 11:35 ` Geoffrey McRae
2019-11-06 6:24 ` Gerd Hoffmann
2019-11-06 8:36 ` David Stevens
2019-11-06 12:41 ` Gerd Hoffmann
2019-11-06 22:28 ` Geoffrey McRae
2019-11-07 6:48 ` Gerd Hoffmann
2019-11-20 12:13 ` Tomasz Figa
2019-11-20 21:41 ` Geoffrey McRae
2019-11-21 5:51 ` Tomasz Figa
2019-12-04 22:22 ` Dylan Reid
2019-12-11 5:08 ` David Stevens
2019-12-11 9:26 ` Gerd Hoffmann
2019-12-11 16:05 ` [virtio-dev] " Enrico Granata
2019-12-12 6:40 ` David Stevens
2019-12-12 9:41 ` Gerd Hoffmann
2019-12-12 12:26 ` David Stevens
2019-12-12 13:30 ` Gerd Hoffmann
2019-12-13 3:21 ` David Stevens
2019-12-16 13:47 ` Gerd Hoffmann [this message]
2019-12-17 12:59 ` David Stevens
2019-11-06 8:43 ` Stefan Hajnoczi
2019-11-06 9:51 ` Gerd Hoffmann
2019-11-06 10:10 ` [virtio-dev] " Dr. David Alan Gilbert
2019-11-07 11:11 ` Gerd Hoffmann
2019-11-07 11:16 ` Dr. David Alan Gilbert
2019-11-08 6:45 ` Gerd Hoffmann
2019-11-06 11:46 ` Stefan Hajnoczi
2019-11-06 12:50 ` Gerd Hoffmann
2019-11-07 12:10 ` Stefan Hajnoczi
2019-11-08 7:22 ` Gerd Hoffmann
2019-11-08 7:35 ` Stefan Hajnoczi
2019-11-09 1:41 ` Stéphane Marchesin
2019-11-09 10:12 ` Stefan Hajnoczi
2019-11-09 11:16 ` Tomasz Figa
2019-11-09 12:08 ` Stefan Hajnoczi
2019-11-09 15:12 ` Tomasz Figa
2019-11-18 10:20 ` Stefan Hajnoczi
2019-11-20 10:11 ` Tomasz Figa
[not found] ` <CAEkmjvU8or7YT7CCBe7aUx-XQ3yJpUrY4CfBOnqk7pUH9d9RGQ@mail.gmail.com>
2019-11-20 11:58 ` Tomasz Figa
2019-11-20 12:11 ` Tomasz Figa
2019-11-11 3:04 ` David Stevens
2019-11-11 15:36 ` [virtio-dev] " Liam Girdwood
2019-11-12 0:54 ` Gurchetan Singh
2019-11-12 13:56 ` Liam Girdwood
2019-11-12 22:55 ` Gurchetan Singh
2019-11-19 15:31 ` Liam Girdwood
2019-11-20 0:42 ` Gurchetan Singh
2019-11-20 9:53 ` Gerd Hoffmann
2019-11-25 16:46 ` Liam Girdwood
2019-11-27 7:58 ` Gerd Hoffmann
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