Re: Why is PCI initialized after the console?

Stephen Williams (steve@icarus.icarus.com)
Thu, 13 Nov 1997 21:33:01 +0000

Geert.Uytterhoeven@cs.kuleuven.ac.be said:
> Anyone who knows what was the good reason for initializing the
> console _before_ the PCI code initialization is called? This causes
> problems for systems where the console is on a PCI device (e.g. a TGA
> console, for which a workaround is used).

PCI VGA devices have a fixed base address. This is a hideous hack of the
PCI spec. in that the VGA space of a PCI video device sits at a fixed location
in the PCI address space. Host pridges are expected to handle this, and
PCI-to-PCI bridges generally have a bit to enable VGA support downstream.

This is how it is possible for say the BIOS to find a display even before
scanning the PCI bus, for example to draw those flashy configuration screens.

So, it matters not whether PCI is scanned before console is configured.

-- 
Steve Williams
steve@icarus.com
steve@picturel.com


"The woods are lovely, dark and deep.  But I have promises to keep,
And lines to code before I sleep, And lines to code before I sleep."