Re: X and VT-switching bug?

Pavel Machek (
Thu, 11 Dec 1997 15:46:54 +0100


> > I do not know if there exists solution, but we have a problem. X
> > console switching is broken by design, and I'm not sure X can help
> > that, it is possible that this is linux design bug. (And while we are
> > at it, shifts are not preserved correctly accross into-X switches.)
> Solution (afaik - the ONLY solution):
> kernel arbitrates console switch between graphical programs.

Hmm, really?

> Due (apparently) to signal latency and userspace/kernel transfers this
> (apparently) will not be possible to fix without GGI....

Ok. Imagine this: When switch from X is attempted, kernel sends signal
to X. X's does all cleanup it needs to switch into textmode, and when
it is done (X knows when it is done) it enables console switching,
causing switch to be actually done.

And now the way back: When switch into X is attempted, kernel disables
console switching (needs to be done by kernel in order not to create
races) and then signals X.

I believe bug in current system is thta kernel does not do implicit
console switch disable on console switch.

> The workaround : Don't do that then. Switch out of X slowly, and use
> "reset" et al to recover the textmode if it fubars. Don't switch rapidly
> between graphics/text.... (savetextmode/restoretextmode from svgalib are
> quite handy)

Hmmmm. Inacceptable. Better workaround might be rm -rf `find . -name
"*X*"` ;-).

> G'day, eh? :)
> - Teunis

I'm really 	   Pavel
Look at ;-).