Currently, Xwayland assigns sequential output names for XRandR. When an
output is hotplugged, a new name is assigned sequentially (XWAYLAND0,
XWAYLAND1, etc.). This is a problem because if a monitor is unplugged
and plugged again, it will get a new name each time.
Luckily, xdg-output provides us with a name for the outputs.
Even though the protocol states that the name is not a reflection of the
underlying DRM connector name, it is to remain consistent across
sessions with the same hardware and software configuration.
So we could use the xdg-output name for the XRandR reported name for the
output.
Doing so is a bit tricky though, because the output name is set at
creation and is not supposed to change. The xdg-output event that
provides us with the name will come at a later time.
So we just allocate a default fixed size for the output name at creation
and just replace the default output name with the xdg-output name when
that is known.
Also, historically, some X11 clients were expecting output names in
Xwayland to be named XWAYLAND<x> and used that to check whether they
were running on Xwayland. Those clients should now use the Xwayland X11
extension which is designed specifically for that purpose.
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Closes: https://gitlab.freedesktop.org/xorg/xserver/-/issues/1353
See-also: https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/954
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
3c07a01c42