Re: [Linux-fbdev-devel] 2 pm3fb questions/problesm ...

[Petr V. <VAN...@vc...>]

On 19 Jun 01 at 18:31, Romain Dolbeau wrote:
> Petr Vandrovec wrote:
> 
> > So you should not have garbage problem on your machine.
> 
> I dont, but Sven Luther is plagued with a x86 box :-)

So he has to write patch. It should not be too hard, as VGA
registers are readable...
 
> > Then you cannot take over vgacon...
> 
> So, in theory, neither do pm2fb and skeletonfb ?

Yes.
 
> I think then that skeletonfb should be flagged as such,
> and all hardware driver that are non-VGA aware also.
> (if it's already documented somewhere, apology,
> I'm used to ignore everything that's labelled VGA :-)

matroxfb can take over vgacon. But I do not think that matroxfb
is best candidate for skeletonfb... 
 
> I haven't ever used any of this stuff, so I guess it's
> really (supposed to be) handled by fbgen or fbcon...

As long as vgacon will store its data directly in videomemory,
there is no way to go - your driver must take a care, as you can
use printk() in this portition of driver, and printk can modify
videomemory...
 
> > It is much better just restore GDC/SEQ/CRTC state (you need
> > to restore only registers needed for proper reading characters
> > from videoram, ~10 registers) to their values on enter to your
> > driver just before you do call to register_framebuffer().
> 
> Given I understand almost nothing in those bits, I assume it's
> the VGA cruft I don't want to understand :-)

Correct! But you should understand how VGA works. How you can
program text mode without VGA knowledge?!
                                Best regards,
                                        Petr Vandrovec
                                        van...@vc...