Subject: Re: wscons versus X servers
To: Jaromir Dolecek <firstname.lastname@example.org>
From: None <email@example.com>
Date: 12/15/1998 16:44:01
> Other issue - if I switch to the screen via Alt-..., which screen
> would show up ? The graphical one or the underlying textual one ?
The wscons driver doesn't know how to switch to or from
graphics mode, it can only deal with text mode.
So it restores the text state of the screen as it was before
it was switched away from, and signals (literally - it sends
a SIGUSR1 to the process) the X server (or svgadoom or
whatever) to let it take over the screen and do the switch to
For switching away there are two ways: If the X server catches
the hotkey it will ioctl() wscons to start the switching process.
If the switch is initiated from outside (ioctl()) the X server
will be notified by SIGUSR1 as in the switch-to case.
This is not specific to wscons; pcvt, freebsd's syscons and
the linux console do it the same way. The syncronisation
protocol originates from SVR?, it sucks btw. because it leaves
room for a number of race conditions.