Unified video+print Xserver / was: Re: Modularization mailing list and initial strawman proposal

[Egbert Eich]

Roland Mainz writes:
 > 
 > The all-in-one video-print Xserver was always there since X11R6.3. It's
 > just hidden away in on of the build options in xc/config/cf/X11.tmpl.
 > AFAIK it was originally debated and favored by one of {Sun, HP} but I do
 > not remember the details anymore. One side was favoring per-user Xprint
 > servers (e.g. one per user and therefore an integrated (or sometimes
 > called "unified") solution) and the other side "global" ones with a
 > seperate print server (which is less resource hungry on multiuser
 > systems (Xterminals, SunRay etc.) and allows to run the Xprint server on
 > the print server machine directly instead of having each workstation
 > running it's own copy). In the meantime (e.g. since X11R6.3) HP added a
 > third option for HP/UX - having one Xserver which can either run in
 > video mode OR (=XOR) print mode (I am not sure whether it allows having
 > both video and print screens running at the same time like the current
 > Xorg code allows).

Having video and print active in a single threaded Xserver would force
video output to wait for the print rendering to finish.
Having both in separate apps would allow the system to do much more fine
grained scheduling between the two.

 > 
 > We have three goals here:
 > 1. One option should be to have a seperate standalone Xprt server with
 > only builtin drivers (mainly for embedding purposes or in cases when not
 > all drivers are needed (for example the SVGprint driver is huge and
 > should only be available as loadable module))
 > 2. Allow Xorg to load print DDXs dynamically 
 > 3. Run the Xorg server either in video, print or a mode where a display
 > has both video and print screens.
 > 
 > The current status looks like this:
 > [1] is the default since X11R6.3
 > [3] is mainly available since X11R6.3 except that there is currently no
 > way to force the server into video-only or print-only mode - the Xorg
 > server just runs with all DDXs it can initalise and that's all (e.g.
 > we're lacking the -servermode option of HP's Xserver).
 > [2] is the most difficult part and needs special care to avoid later ABI
 > updates just because we forgot something (at some point HP could help
 > here via contributing their knowledge as the Xserver in HP/UX loads the
 > print DDX dynamically, too)
 > 

I'd expect HP would do this if they feel this is a viable technology 
in the future.

Cheers,
	Egbert.