Hello to everyone!
My setup:
Host: Pop OS! 20.10 with X11.
LXD: v4.0.4, installed via snap.
LXD container image: Ubuntu 20.04.1.
X11 container setup as described by Simos in his blog entry “How to easily run graphics-accelerated GUI apps in LXD containers on your Ubuntu desktop”, which in general works well for me.
And here is my issue: I try to get Zoom screen sharing working when Zoom is running inside a LXD container. While I can start screen sharing from Zoom, the screen I share remains black for the other participants. Zoom doesn’t show me any error message. This issue, i.e. a black screen when sharing, is addressed in the Zoom Help Center:
[https://support.zoom.us/hc/en-us/articles/202082128-Black-Screen-During-Screen-Sharing](Link to Zoom Help Desk)
Following the suggestion there and running xcompmgr inside of the container gives me the error message:
$ xcompmgr -c -l0 -t0 -r0 -o.00
Another composite manager is already running (0x400011)
So there is a composite manager running and thus I cannot start another one in the container as suggested in the Zoom help desk entry.
Digging a bit further, I find that inside the container, the X server reports to support the Composite extension:
$ xdpyinfo | grep Composite
Composite
But when I ask inxi inside of the container what compositor is running, I get:
$ inxi -Gxx
Graphics: Device-1: Advanced Micro Devices [AMD/ATI] Renoir vendor: Lenovo driver: amdgpu v: kernel bus ID: 07:00.0
chip ID: 1002:1636
Display: server: X.Org 1.20.9 driver: amdgpu resolution: 1920x1080~60Hz, 2560x1440~60Hz
OpenGL: renderer: AMD RENOIR (DRM 3.38.0 5.8.0-7630-generic LLVM 10.0.0) v: 4.6 Mesa 20.0.8 direct render: Yes
So, no X11 compositor shown.
Running the same command on the host, i.e. outside of the container, I get:
$ inxi -Gxx
Graphics: Device-1: Advanced Micro Devices [AMD/ATI] Renoir vendor: Lenovo driver: amdgpu v: kernel bus ID: 07:00.0
chip ID: 1002:1636
Device-2: Chicony Integrated Camera type: USB driver: uvcvideo bus ID: 2-2:2 chip ID: 04f2:b6d0
Display: x11 server: X.Org 1.20.9 compositor: gnome-shell driver: amdgpu,ati unloaded: fbdev,modesetting,vesa
resolution: 1: 1920x1080~60Hz 2: 2560x1440~60Hz s-dpi: 96
OpenGL: renderer: AMD RENOIR (DRM 3.38.0 5.8.0-7630-generic LLVM 11.0.0) v: 4.6 Mesa 20.2.1 direct render: Yes
As I am running a Gnome desktop, it is little surprise that it shows the gnome-shell as X11 compositor.
My conclusion is that while the container has access to the X11 server, it does not have access to the X11 compositor and thus the Zoom screen sharing, which needs the X11 compositor, does not work.
Any idea what I need to change in my setup in order to get Zoom screen sharing working from inside a LXD container?
Best,
Bernd