Weston: Single CRTC cloning on multiple connectors. How?

[Sebert, Holger.ext]

Hi,

I hope this is the right place to ask my question, if not, please
point me into the right direction. Googling around did not bring
any useful results. --

I am using Weston 9.0.0 and would like to duplicate monitor output
on various connectors (HDMI, DisplayPort, etc.), i.e. use clone-mode.

I tried the "same-as" parameter in the "output"-section of my
weston.ini file, but it did not have the desired effect. The relevant
sections of my weston.ini look like follows:

	[core]
	backend=drm-backend.so

	...

	[output]
	name=HDMI-A-1
	mode=1920x1080

	[output]
	name=DP-1
	same-as=HDMI-A-1

	[output]
	name=DP-2
	same-as=HDMI-A-1

The connector names are those which I found in "/sys/class/drm".
There is exactly one graphics card in my machine ("card0").

Interestingly, setting the resolution to something different than
"1920x1080" works. So Weston does indeed recognize these entries.
However, it does not clone the display.

How do I activate display cloning in weston.ini?

Best,
Holger