Re: [Xen-devel] [PATCH 0/1] cameraif: Add ABI for para-virtualized

[Oleksandr Andrushchenko <andr2000@xxxxxxxxx>]

Hi, Laurent!

On 09/10/2018 03:48 PM, Laurent Pinchart wrote:
> Hi Oleksandr,
>
> Thank you for the patch.
>
> On Tuesday, 31 July 2018 12:31:41 EEST Oleksandr Andrushchenko wrote:
> > From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> >
> > Hello!
> >
> > At the moment Xen [1] already supports some virtual multimedia
> > features [2] such as virtual display, sound. It supports keyboards,
> > pointers and multi-touch devices all allowing Xen to be used in
> > automotive appliances, In-Vehicle Infotainment (IVI) systems
> > and many more.
> >
> > This work adds a new Xen para-virtualized protocol for a virtual
> > camera device which extends multimedia capabilities of Xen even
> > farther: video conferencing, IVI, high definition maps etc.
> >
> > The initial goal is to support most needed functionality with the
> > final idea to make it possible to extend the protocol if need be:
> >
> > 1. Provide means for base virtual device configuration:
> >   - pixel formats
> >   - resolutions
> >   - frame rates
> > 2. Support basic camera controls:
> >   - contrast
> >   - brightness
> >   - hue
> >   - saturation
> > 3. Support streaming control
> > 4. Support zero-copying use-cases
> >
> > I hope that Xen and V4L and other communities could give their
> > valuable feedback on this work, so I can update the protocol
> > to better fit any additional requirements I might have missed.
> I'll start with a question : what are the expected use cases ?
The very basic use-case is to share a capture stream produced
by a single HW camera to multiple VMs for different
purposes: In-Vehicle Infotainment, high definition maps etc.
all running in different (dedicated) VMs at the same time
>   The ones listed
> above sound like they would better be solved by passing the corresponding
> device(s) to the guest.
With the above use-case I cannot tell how passing the
corresponding *single* device can serve *multiple* VMs.
Could you please elaborate more on the solution you see?
> > [1] https://www.xenproject.org/
> > [2] https://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=xen/include/public/io
> >
> > Oleksandr Andrushchenko (1):
> >    cameraif: add ABI for para-virtual camera
> >
> >   xen/include/public/io/cameraif.h | 981 +++++++++++++++++++++++++++++++
> >   1 file changed, 981 insertions(+)
> >   create mode 100644 xen/include/public/io/cameraif.h
Thank you,
Oleksandr

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