Hitchhiker's Guide to Openbsd

CTRL-ALT-Backspace: This hopefully causes X to immediately terminate, along with all X 
applications that are running. Of course, during the configuration process, you don't have any 
http://www.openbsd.org/faq/faq11.html (7 of 14)9/4/2011 10:02:17 AM

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11 - The X Window System
applications running, so this is not a problem (and in fact, at this point, this is your best way to 
exit X). 
●
SSH into the box, and "
pkill
Xorg", which may kill the X process, and may return you to a 
usable console. 
●
SSH into the box and reboot it. 
●
Reset or power button. Sometimes things go really bad. Yes, it is usually good to get X running 
before you load critical applications on the system. Sometimes, a bad X configuration will hang 
the entire machine to the point that only a hard reset will resolve the problem. 
Fortunately for us, CTRL-ALT-Backspace does the job here, and we are returned to a command prompt. 
So now we need to see if we can figure out what is wrong. First, we should look at what Xorg thinks is 
going on, and that is recorded in the file 
/var/log/Xorg.0.log
. In this case, it appears that X 
thinks all is running fine, there are no obviously significant errors shown in the log (lines that start with 
an "
(EE)
" are errors). 
Here is where knowing your hardware comes in handy. Attaching this system to a different monitor 
while it is showing the blank screen produces a "Sync. Out of Range" message on the display. So, 
apparently the configuration X gave us will not run on this monitor, and may not run on ANY monitor, 
if a video mode was selected that isn't possible for this particular card (keep in mind, X is looking at the 
chips on the card, and what they are potentially capable of, not how the manufacturer put it all together). 
Different monitors will do different things when the timing is way off, some will attempt to display what 
they can, others will drop to power saving mode, some will make horrible noises, some will display 
useful messages on the screen. This monitor seems to do none of the above. A note is made to NOT use 
this monitor for initial X configuration in the future. 
Looking through the generated xorg.conf.new file, we see this: 
Section "Monitor"
#DisplaySize 370 270 # mm
Identifier "Monitor0"
VendorName "SNY"
ModelName "SONY CPD-G400"
### Comment all HorizSync and VertSync values to use DDC:
HorizSync 30.0 - 107.0
VertRefresh 48.0 - 120.0
Option "DPMS"
EndSection
As a test, let's try using DDC ("Data Display Channel", a way the monitor can tell the computer and 
video card what it is capable of), and see what happens. This time, we get the X mesh pattern and the 
moving cursor, which is all we expect when invoking X in this way (we terminate X using the CTRL-
ALT-Backspace trick above). It is (again) a very low resolution, but it is working, so we can be pretty 
http://www.openbsd.org/faq/faq11.html (8 of 14)9/4/2011 10:02:17 AM

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11 - The X Window System
sure we have a timing and resolution problem. We'll restore the "HorizSync" and "VertRefresh" lines as 
they were, as we have verified this monitor's specs through a bit of Internet searching. 
Let's try to force Xorg to a particular resolution, and see if we have any luck. In the 
Section 
"Screen"
part of the xorg.conf file, we want to add a couple lines. The added lines are shown in bold: 
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"