Passing multi-screen layout to KMS driver

[Michael Thayer]

Hello,

I'm afraid I'm not subscribed to the list, so I would greatly appreciate 
a CC on replies (if any).  I have been fiddling with our 
(not-upstreamed) VirtualBox guest drm driver to make it work better with 
the Wayland version of GNOME Shell in Fedora 25.

One problem that I have run into (from my testing it seems to affect 
Qemu too) is that we use an emulated graphics tablet device to make the 
guest pointer position match the host one.  GNOME Shell nicely maps the 
range of the device to the full virtual desktop, as does X.Org.  Unlike 
X.Org though, GNOME Shell/Wayland does not create a single framebuffer 
in video RAM for the whole desktop, where we could deduce the relative 
layout of the screens by looking at the offset of their crtcs in that 
framebuffer.

So I would be interested to know whether anyone else has thought about 
this problem, and possibly even about an interface to let the compositor 
pass the information.  If not, would people be open to the idea?  I 
would much rather have something generally agreed on than hack something up.

Thanks.

Regards
Michael
-- 
Michael Thayer | VirtualBox engineer
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