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Archive for March 5th, 2009

X Server Auto-Configuration Requires a Monitor: Duh

The used Optiplex GX270 that will eventually become my mother’s “new” PC has been booting absolutely reliably in the basement, so whatever was troubling it a few months ago seems to have Gotten Better By Itself. I don’t have to like that, but so far, so good.

This morning I ssh-ed into it, as I do every few days, then fired up krdc on my desktop, which immediately complained that there wasn’t anything there to connect with. Uh-oh

But the ssh worked, so at least there’s a Linux system at the end of that network cable.

A changing cast of PCs has gone through the basement lab in that time and I’ve been swapping the desktop monitor among them. Most recently, a friend gave me an ancient Aptiva that might turn into a dedicated controller and I’d left the monitor connected to it.

After I figured out that the monitor wasn’t hitched to the Optiplex, traced the cable, and fixed that oversight, I was confronted with a command-line prompt. A bit of rummaging in /var/log/Xorg.0.log turned up some useful information:

(II) intel(0): Output VGA disconnected
(EE) intel(0): No valid modes.
... <snippage> ...
(EE) Screen(s) found, but none have a usable configuration.
Fatal server error:
no screens found

In the Bad Old Days, you told X exactly what output to produce by providing modelines that specified the exact video timings. That was fraught with peril, as you could do the Digibomber thing to a fussy fixed-frequency monitor by specifying timings beyond its abilities.

Nowadays, the X server feels around, detects the video card, asks it what it can produce, detects the monitor, asks it what it can display, figures out the best match from the ensuing matrix of possibilities, and shazam slaps up a GUI. Might not be exactly what you want, but more likely than not it’ll be pretty close and you can apply some tweakage to get it right.

If there’s no monitor connected, then the X server doesn’t know quite what to do. I’m sure it’s possible to specify a default fallback configuration, but maybe it’s better to just ensure the monitor is always connected. Those cute little screws on the connector might be a clue, eh?

The command line continues to work, of course, so you can figure this stuff out either locally or through ssh. Alas, it’s really hard to reconnect a monitor cable through ssh.

If you’re still not convinced to improve your command-line chops, I commend to your attention Stephenson’s In the Beginning was the Command Line.

Memo to Self: Use the Screws!

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