Re: [Qemu-devel] [RFC,Draft] ui: add an embedded Barrier client

[Gerd Hoffmann <kraxel@redhat.com>]

  Hi,

> >> +        p = write_short(ib, p, 1920); /* width */
> >> +        p = write_short(ib, p, 1080); /* height */
> > 
> > Hmm.
> > 
> > This is the screen size I guess?  Which you don't know ...
> > What this is used for?
> > Should we maybe use INPUT_EVENT_ABS_MAX here?
> > 
> 
> Yes, it's screen size but we can't use INPUT_EVENT_ABS_MAX.
> 
> In fact Barrier can manage more than 2 displays:
> 
>    0            x1           x2           x3
> 
> 0  +------------+------------+------------+---
>    |            |            |            |
>    |  localhost |    VM-1    |   VM-2     |
>    |            |            |            |
> y1 +------------+------------+------------+---
>    |            |            |            |
>    | remotehost |            |            |
>    |            |            |            |
> y2 +------------+------------+------------+---
>    |            |            |            |
> 
> So Barrier will send events to localhost while x(mouse) is between 0 and
> x1, to VM-1 while it is between x1 and x2, and to VM-2 between x2 and
> x3. So we need to know the size of the display to have x2.

Ok, I see.

> Normally when the barrier client runs into an OS it intercepts the
> screen resizing information and send them to the server. In our case we
> cannot (for instance if we use a vfio display)

Yes, for the vfio case we can't (unless it is a vgpu).

Otherwise looking up the DisplaySurface (via QemuConsole) and checking
the size should work.  Not a priority given that vfio is probably the
most interesting use case.

How does barrier send input events to physical machines btw?

> but I plan to add
> properties to the input-barrier object to provide the information at
> least statically.

Makes sense.

> The barrier server runs only on the machine with the mouse and the
> keyboard. Other machines have normally the barrier client daemon to
> inject the mouse and keyboard events in the OS.

Ok.

> I will try to add a keyboard remapping as we have with VNC because it
> doesn't work well with my french keyboard (AZERTY). Or perhaps I can use
> the "button" id instead of the keyid but I don't now how to map the
> value to a qcode.

Depends on how the button id is defined.  If it is one of the usual
keycodes it should be easy and should work better than reverse mapping.

cheers,
  Gerd