From: Marcus Sundberg <mackan@stacken.kth.se>
  To  : ggi-develop@eskimo.com
  Date: Sun, 07 Mar 1999 13:36:14 +0000

Re: DGA target kills my X.

Daniel Elenius wrote:
> 
> >>But note that the DGA that LibGGI uses has an extra feature:
> >>If you have a fbcon driver for your card loaded you can set
> >>GGI_DGA_FBDEV=<device> where <device> is the framebuffer device node,
> >>and then the DGA target will mmap() that instead, thus you only
> >>need permissions on <device> instead of /dev/mem.
> 
> But still...
> 
> daniel@i203:/usr/src/degas/lib/libggi/programs/demos/warp-ggi$ cat /proc/fb
> 0 VESA VGA
> daniel@i203:/usr/src/degas/lib/libggi/programs/demos/warp-ggi$ env |grep GGI
> GGI_DISPLAY=DGA
> GGI_DGA_FBDEV=/dev/fb0
> daniel@i203:/usr/src/degas/lib/libggi/programs/demos/warp-ggi$ warp cthugha.pcx
> _ggi_XF86DGAGetVideo: failed to mmap /dev/fb0 (Invalid argument)
> display-DGA: Unable to map video memory!
> Error opening GGI display.
> 
> I still haven't set up the 320x200 X modeline, but I shouldn't get
> THIS error message, right? In other words: What have I done wrong?

As you can't change modes with the VESA framebuffer driver it probably
doesn't support mapping more memory than the mode of the framebuffer
uses.

DGA however maps the entire video memory as reported by the X-server,
so GGI_DGA_FBDEV most likely only works if you have a fbcon driver
which is made for your graphic board. As DGA was designed to 
require root privs we there isn't anything we can do about it.

//Marcus
-- 
-------------------------------+------------------------------------
        Marcus Sundberg        | http://www.stacken.kth.se/~mackan/
 Royal Institute of Technology |       Phone: +46 707 295404
       Stockholm, Sweden       |   E-Mail: mackan@stacken.kth.se