Re: [PATCH v6] Add udmabuf misc device

From: Tomeu Vizoso
Date: Wed Jul 04 2018 - 03:26:52 EST


On 07/04/2018 07:53 AM, Gerd Hoffmann wrote:
On Tue, Jul 03, 2018 at 10:37:57AM +0200, Daniel Vetter wrote:
On Tue, Jul 03, 2018 at 09:53:58AM +0200, Gerd Hoffmann wrote:
A driver to let userspace turn memfd regions into dma-bufs.

Use case: Allows qemu create dmabufs for the vga framebuffer or
virtio-gpu ressources. Then they can be passed around to display
those guest things on the host. To spice client for classic full
framebuffer display, and hopefully some day to wayland server for
seamless guest window display.

qemu test branch:
https://git.kraxel.org/cgit/qemu/log/?h=sirius/udmabuf

Cc: David Airlie <airlied@xxxxxxxx>
Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>

I think some ack for a 2nd use-case, like virtio-wl or whatever would be
really cool. To give us some assurance that this is generically useful.

Tomeu? Laurent?

Sorry, but I think I will need some help to understand how this could help in the virtio-wl case [adding Zach Reizner to CC].

Any graphics buffers that are allocated with memfd will be shared with the compositor via wl_shm, without need for dmabufs.

Daniel Stone [added to CC] commented though that this could be useful for browsers that composite pages with a nested Wayland compositor, to avoid having to blit each layer so that the EGL platform notifies the compositor of new contents.

Cheers,

Tomeu

Plus an ack from dma-buf folks (nag them on irc, you don't have them on Cc
here).

Hmm, does MAINTAINERS need an update then? Maintainer and mailing lists
listed in the "DMA BUFFER SHARING FRAMEWORK" entry are on Cc.

Who should be Cc'ed?

Then this is imo good to go.

I assume you'll push it to drm-misc, like all the other dma-buf stuff?

Can do that, sure, after collecting the acks ...

thanks,
Gerd