setting up xorg.conf

Carl Karsten carl at
Tue Apr 12 12:47:40 CDT 2005

xorg guys have some interest in something that I thought I had seen here 
but I can't find it.  Also, anyone leaning on ddcprobe may be interested 
in what I found.

google ddcprobe: "ddcprobe 
claims to do a "Videocard DDC probe". However, in the course of 
troubleshooting bug 108681, I learned from Mike Harris that there is no 
such thing.  I think it would be less misleading if it was called 
something like a "Videocard VBE probe". Even if that's not the best 
phrase either, it's much better and much closer to the truth than 
"Videocard DDC probe".

 From #xorg:

CarlK: it seems a common problem is getting the valid resolutions in 
CarlK: valid = ones that will work with my hardware (video card, video 
memory and monitor)
ajax: if we had a way to probe DDC on a card without running all of X, 
we could do that pretty reliably
ajax: linux might give you enough info through sysfs to make that possible
CarlK: ever heard of ddcprobe?
libv: CarlK: that most likely uses VESA
CarlK:  /usr/sbin/ddcprobe - can't figure out where it comes from - no 
man or info
libv: which makes it a BIOS dependant function, which only makes it 
possible on the primary graphics card
ajax: probably the easy solution is to bump the default resolution to 
800x600, use DDC by default, and cache the results of the DDC probe from 
the last server startup
ajax: that last bit being important, so the monitor still works even if 
you start X with it powered down.

JakubS_: so there should be no problem with only primary card - from 
what i have seen there is bios image for video card in /sys
JakubS_: it would probably have to be run on emulator, like x server does

If someone can give me the subject(s) of the ubuntu threads (pretty sure 
it was here) I'll forward it to xorg at

Carl K

More information about the ubuntu-devel mailing list