Re: please explain to me why video/bios shadowing must be disabled to use graphics...

[Stas Sergeev <stssppnn@yahoo.com>]

Hello.

Bart Oldeman wrote:
> Well VGA only uses standard ports so the only problem is to pass the
> VBIOS initialization in the first place, that is executing the code at
> c000:0003
Where does it do that? I have found only
init_vga_card(), but that doesn't seem to be
the place. Also I searched the +g log for
c000:0003 and found nothing...

> On some graphics cards
> this init routine requires additional open ports and maybe even
Yes, my Radeon is trying, but only if all the
extra ports are *disabled*, it works.

> Some people reported black screens, or even machines hanging which
> happens when the VBIOS init routine is called.
Of course, that was me:) But does the problem still
exist after 1.1.3.1?
Anyway, no one of the people that started that thread,
had lock-ups on startup, they just have dosemu in a terminal
mode (should it display graphics then? :), why do you
think it can by any chance be the same problem?

> Maybe by just bypassing the VBIOS init you can avoid this problem; I
> just have never looked into that possibility.
I tried to comment out the end of the init_vga_card()
(which seems to call int10 but for what?) and dosemu
started fine and without the card logo. However none
of the video modes (including VGA) were available.
Have to figure out why yet.

> The VBE 2.0 spec defines a protected mode interface - if DOSEMU would
> use that it could ask which ports should be used and opened.
If everything could be so easy... I tried this already
and my Radeon is completely silent, returning an empty
list:( That is why, I think, XFree 3.3.6 or 4.1 are not
able to set any VESA modes, but not the 4.2, which can!