On Wed, Jul 10, 2002 at 08:45:02PM +0900, Bang Jun-Young wrote:
> On Wed, Jul 10, 2002 at 07:55:18PM +0900, itojun@iijlab.net wrote:
> > >AFAIK, most graphics cards manufactured so far need such timing
> > >information for mode switch. It's not chip dependant. If it were,
> > >for what does XFree86 provide common mode lines in XF86Config file? 
> > 
> > 	i'm no expert in various VGA cards these days, but isn't it better
> > 	to let BIOS handle it?  i.e. call VGA BIOS for initialization and
> > 	let it initialize the parameter, instead of cooking up parameters.
> > 	kvm86.c looks promising for this...(assuming VGA BIOS gives you
> > 	enough functionality)
> 
> It would make sense with i386, but not with others. There's no
> known/easy/MI method to set screen to 1280x1024 at 75 Hz on sparc64,
> for example. Even on i386, VESA BIOS provides limited number of video
> modes, so display drivers have to know how to do mode switching. 

Maybe the BIOS calls could be used to get text mode for ddb?
With some trap to force X11 to release and reaquire the current
mode (usually short circuited) if/when the system continues.
(also useful to request this on sleep/resume cycles).

I tried some quick hacks last week - got ddb to go to the console
from a text window, but not from a graphics one.....
For ddb/panic being able to get back to the graphics window
is nothing like as important as seeing the panic message!

	David

-- 
David Laight: david@l8s.co.uk