After more tests, I must conclude that xorg for that display adapter was
broken again between alpha6 and beta.
Whichever xorg.conf I use from autodetected or adding my a6-working
patch to it, the display will fail the way I described (hang or
spontaneous reboot).
Only If I boot in recovery mode (and choose resume or xfix) will the
display work.
So, in summary :
6.04: worked beautifully at 1024x768
7.10: totally broken
8.04a: works, but autodetects 800x600 only, needs 1024x768 patch
8.04b: totally broken again
I diffed the config I used in a6 with the one in beta after same patch :
After more tests, I must conclude that xorg for that display adapter was
broken again between alpha6 and beta.
Whichever xorg.conf I use from autodetected or adding my a6-working
patch to it, the display will fail the way I described (hang or
spontaneous reboot).
Only If I boot in recovery mode (and choose resume or xfix) will the
display work.
So, in summary :
6.04: worked beautifully at 1024x768
7.10: totally broken
8.04a: works, but autodetects 800x600 only, needs 1024x768 patch
8.04b: totally broken again
I diffed the config I used in a6 with the one in beta after same patch :
$ diff xorg.alpha6.conf xorg.beta.conf
< Driver "mouse"
> Driver "vmmouse"
> Section "ServerLayout"
> Identifier "Default Layout"
> Screen "Default Screen"
> EndSection
Thanks in advance for restoring working state.