Dual (virtual) screen support under Xephyr (or Xnest)?

m h sesquile at gmail.com
Wed Nov 24 07:06:16 PST 2010

Hey Folks-

I'm trying to debug some multiscreen issues with a wm [0] I'm
contributing to.  This wm is scriptable so it makes development pretty
cool, you write a test and it runs the tests in Xephyr.

There are some issues with dual monitor support which I'd like to get
ironed out.  Sadly I can't get Xephyr, Xdmx or Xnest to work with dual
(virtual) screens.  It be great to test under them rather than using
my real desktop.

Here's what I've tried:

# old command
Xephyr -br +extension RANDR +xinerama -mouse evdev -screen 500x600
-screen 400x300+500+0  :1 -ac & (sleep 1; env DISPLAY=:1
~/work/pylibs/qtile/qtile -d -c /home/matt/.config/qtile/mattdev.py  &
env DISPLAY=:1 xterm)

Brings up 2 windows, but I can't use xrandr to place them next to each
other.  In fact xrandr only sees (can connect to) one of the windows.
Both windows seem to overlap.

# Xdmx attempt
Xephyr :3.0 -a -ac -br +extension RANDR +xinerama -screen 300×400 &
Xephyr :4.0 -a -ac -br +extension RANDR +xinerama -screen 200×400 &
(sleep 2; Xdmx :5 -display localhost:3 -display localhost:4 +xinerama) &
(sleep 4; env DISPLAY=:5 ~/work/pylibs/qtile/qtile -d -c
/home/matt/.config/qtile/mattdev.py  & env DISPLAY=:5 xterm)

Seems to bring up 2 windows next to each other, but doesn't want to
let the wm draw anything other than windows:
(**) dmx: dmxErrorHandler: RenderBadPicture (invalid Picture parameter)
(**) dmx:                  Major opcode: 143 (RENDER)
(**) dmx:                  Minor opcode: 10 (RenderTrapezoids)
(**) dmx:                  ResourceID:   0x2000ae
(**) dmx:                  Failed serial number:  1195
(**) dmx:                  Current serial number: 1196

# xnest

Xnest :1 -ac -br +xinerama -scrns 2 -geometry 1000x500 & (sleep 1; env
DISPLAY=:1 ~/work/pylibs/qtile/qtile -d -c
/home/matt/.config/qtile/mattdev.py  & env DISPLAY=:1 xterm)

This segfaults.

I'm running on an intel t61p thinkpad with gentoo.  xorg 1.7.7, intel
drivers 2.13.

Any hints or suggestions would be wonderful.  As a last resort I could
develop under my real (non-nested) wm.....

thanks much!


0 - http://www.qtile.org/

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