Framebuffer or standard VGA ?

Antony Stone Antony at
Wed Sep 11 03:18:01 CEST 2002

On Wednesday 11 September 2002 7:22 am, Steve M. Gehlbach wrote:

> > > Maybe someone knows if alphanumeric mode setup is via the standard VGA
> > > register set on most modern VGA cards.
> >
> > I am afraid you are wrong. For modern VGA cards, there is actually no
> > alphanumeric mode. These alphanumeric mode were simulated by BIOS or
> > drivers. The worst thing, if you have no documents about these extended
> > registers, you have no way to drive the clock gen for Dot clock, Hsync,
> > Vsync.
> Are you saying that it is not possible to use a text console with Linux
> (vgacon.c) with modern VGA cards (BIOS mode 3)? Only framebuffer? Or are
> you saying that without extra information (ie, the BIOS or the manuals) you
> can't init it into mode 3?  I don't understand your answer.
> I thought most vga cards were register compatible with the legacy VGA
> register set, only that there were a lot of other (sometimes secret) things
> to setup.  Is this wrong?

Forgive my ignorance, but isn't this what the Bios chip on the VGA card 
itself is for (in the case where you have a physical card plugged into the 
motherboard, and not an all-in-one integrated motherboard chipset) ?

I mean, surely that's the reason why, when you turn on a 'standard' PC with a 
normal graphics card and a normal Bios, you see the starup messages for the 
graphics card *first*, and *then* you see the Bios logo and config screen....?

Couldn't LinuxBios simply call the appropriate init code in a graphics card 
Bios in order to get a text console, and then carry on afterwards in the same 
way a normal boot loader would ?



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