Re: OpenGL-based framebuffer concepts

["Antonino A. Daplas" <adaplas@gmail.com>]

Ondrej Zajicek wrote:
> On Wed, May 31, 2006 at 07:21:11AM +0800, Antonino A. Daplas wrote:
>>> 2) To modify appropriate fbdev drivers to not do mode change at startup.
>>>    Fill fb_*_screeninfo with appropriate values for text mode instead.
>> Most drivers do not change the mode at startup.  Do not load fbcon, and
>> you will retain your text mode even if a framebuffer is loaded. 
> 
> Yes, but i wrote about _using_ fbcon and fbdev without mode change.

boot with fbcon=map:9 /* or any number greater than the number of fbdev's loaded */

> 
>>> 3) (optional) To modify appropriate fbdev drivers to be able to switch
>>>    back from graphics mode to text mode.
>> And a few drivers already do that, i810fb and rivafb.  Load rivafb or i810fb,
>> switch to graphics mode, unload, and you're back to text mode.
> 
> I though about being able to explicitly change mode from graphics to text 
> (for example when fbdev-only X switch to fbcon) while using fbdev.
 
This will require the following:

1. a generic text mode framebuffer driver, ie, an fbdev version of vgacon
2. a chipset driver that can fully restore VGA text mode.

The framebuffer layer already has helper functions that will save and restore
the standard VGA registers. It's the save/restore of extended registers that
only the chipset driver know about which is lacking.
 
Once the above 2 are satisfied, the infrastructure is already present that
will do what you want.

Tony