On 2019-01-06 11:29 a.m., Ondřej Grover wrote: > Package: xserver-xephyr > Version: 2:1.19.2-1+deb9u5 > Severity: normal > > Dear Maintainer, > > I'm trying to use Xephyr to test my awesome (WM) multi-screen setup. > As per instructions found on the Internet I spawned a Xephyr server with 2 > screens and the Xinerama and RANDR extensions activated: > > Xephyr -screen 960x540+0+0 -screen 960x540+960+0 +extension RANDR +xinerama > :1 & > > This spawns 2 windows side-by-side (due to the +X+Y panning information, but > also works without it and has the same issue), labeled :1.0 and :1.1 > However, when I ask xrandr about the screens, it sees only one screen/output > > DISPLAY=:1 xrandr > xrandr: Failed to get size of gamma for output default > Screen 0: minimum 160 x 160, current 1920 x 540, maximum 1600 x 1200 > default connected 960x540+0+0 (normal left inverted right x axis y axis) 0mm > x 0mm > 1600x1200 0.00 > 1400x1050 0.00 > 1280x960 0.00 > 1280x1024 0.00 > 1152x864 0.00 > 1024x768 0.00 > 832x624 0.00 > 800x600 0.00 > 720x400 0.00 > 480x640 0.00 > 640x480 0.00 > 640x400 0.00 > 320x240 0.00 > 240x320 0.00 > 160x160 0.00 > 960x540 0.00* > > So when I start awesome (WM) on this display, it detects only the first > screen/output > > DISPLAY=:1 awesome & > > Now if I attempt to start an xterm on the first screen, it works correctly > > DISPLAY=:1.0 xterm & > > I can even move this terminal toward the right screen and it becomes visible > on the second (:1.1) screen, so perhaps Xinerama is working. > > However, If I attempt to start an xterm on the second screen directly, it > fails (even without awesome) > > DISPLAY=:1.1 xterm & > xterm: Xt error: Can't open display: :1.1
That's the point of Xinerama. :) It combines the "physical" screens to a single logical one. You can see the information about the "physical" screens provided by the Xinerama extension via xdpyinfo -ext XINERAMA > My feeling so far is that the second (possibly any extra) display is not > properly advertised or registered. Perhaps the RANDR extension is not working > properly? Xinerama and RandR are generally incompatible. The Xorg server completely disables RandR when Xinerama is enabled. I suspect Xephyr leaves it enabled by accident, not intentionally. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer
