Bug#420300: Workaround found, but no solution for the bug

[Hans-Joachim Zierke <hajo2007@Zierke.com>]

Several attempts were undertaken, to solve the problem with different
video modes, especially modes very close to each other. No success.


Several kernel attributes for the framebuffer were tried, like 
init - noinit etc. No success.


Different settings for the X-Server were tried. Of these, setting
        Option          "UseFBDev"              "true"
has shown an effect: Instead of a system crash after every ~20th switch
or so, the system crashed for every ~2nd switching.


Workaround for the problem is the following: Don't use the MGA driver 
for the X-Server. Instead, use the framebuffer driver for the X-Server.
After doing so, the system didn't crash for several days, which is only
a preliminary result, but already a phantastic one.
(I haven't seen such unreliable system since the days of DOS cache 
programs playing with the A20 gate.)


I'm not sure, which MGA driver is at fault: fb or xorg.



Ciao
Hans-Joachim