Re: How to catch oopses under X-Windows.

David Woodhouse (
Thu, 10 Jul 1997 18:55:43 +0100 wrote:
> I currently work with x86-Linux 2.1.40. It works fine most of the time but
> ca. every 3rd day it hangs up and I can't figure out why: keybord and mouse
> don't work - so I can't leave X-Window (XFree86 3.2) and there is nothing to
> find in the kernel-message-files (somewhere under /var/...).
> Is there any other way to catch these errors - perhaps sending them to any
> other interface like parallel or serial ports, so that they will be printed -
> or to reset video-card and print it direct on the screen ????

You can send them to a serial console, certainly. You might want to amend the
code slightly so that printks are sent out to the serial port, but the device
that /dev/console points to remains the screen, as normal.

The way I did it was to find an old MDA board and use it as a console.
mda-0.11 on your favourite mirror contains a kernel patch
which will register the MDA screen as a console, so kernel panic messages will
get sent to it.

I am intending to provide a similar patch for using a printer in a similar
fashion (mainly because I got _very_ tired of repeatedly copying down panic
messages by hand with recent 2.1.4x kernels), but I'm a bit short of time at
the moment. To do that, you probably want to only print messages above a
certain log level, in order to avoid chucking reams of paper out whenever you
do something like trying to use a dead floppy disc.

As for resetting the video card and printing such panic messages to the main
screen, it's not really possible because the kernel knows nothing about the
video card, and so hasn't a whelk's chance in a supernova of being able to put
it into a well-defined state and display text on it. You'd need GGI for that.

David Woodhouse,	CB3 9AN 		 Tel: 0976 658355	 Tel: 01279 402332