xf86-video-dummy with randr support - is anyone else interested? Alternatives?

Leho Kraav leho at kraav.com
Sun Jul 10 07:10:42 PDT 2011


Hi all

My goal is to use a DisplayLink USB display with Xorg on a laptop in a 
sane fashion, which pretty much seems to mean RandR support one way or 
the other.

Since USB display is a very comes-and-goes device, I'm figuring I better 
use a permanent virtual secondary screen using xf86-video-dummy shared 
with x11vnc and put another fbdev Xserver running vncviewer as an "eye" 
to that virtual desktop as I need to. This replaces the usual complete 
reconfiguration of windows and desktops of a regular monitor plug/pull, 
which also I don't think is even possible right now with an USB display.

alias connect-doublesight-x='x11vnc -display :0.1 -noxrandr -q 
-localhost -bg; startx ~/.xinitrc-vncviewer -- :1 vt7 -sharevts -quiet 
-config xorg-displaylink.conf &'

It works quite well and performance over vnc is not an issue at all for 
the scenario, in case anyone is wondering.

Now the primary problem is that Awesome WM is not capable of recognizing 
xf86-video-dummy as a secondary screen for quick window dispatch back 
and forth with Mod4-o and I really want to do this often. This is 
because xf86-video-dummy doesn't know RandR and apparently doesn't 
participate in the big virtual RandR desktop.

I don't want to do Xinerama, since I would lose the ability to also 
connect real monitors on the go without having to restart my whole X 
session.

Alternatives? I cannot find any other driver that would act as a virtual 
screen like xf86-video-dummy, but would provide a RandR-compliant 
framebuffer for me. I don't think Xephyr, Xdmx, Xvnc, x2x and whatnot 
others can help me here, Awesome needs to see something as a regular 
RandR screen next to the built in panel. Or is it possible to fake this 
display somehow while being forwarded to another Xserver copy?

Is there an itemized work list somewhere on what it would take to get 
xf86-video-dummy into RandR world?

In case any awesome devs are here, would it actually make sense to patch 
it on awesome side? Which work list is greater?

Thanks for reading.

-- 
Leho Kraav, M.Sc.

http://about.me/lkraav



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