Re: PCI and Expansion ROM

[rwalter@auspex.com (Richard Walter)]

ccurley@dwarf.fc.hp.com wrote:

> Another course of action is to abolish vestigial Mess-DOS-isms such as
> this whole section (6.3.3). Then people who are using real operating
> systems on real computers won't keep tripping over incompatibilities
> because they aren't using 80586s to emulate 8088s.

I'd call the C0000h - E0000h ROM window a PC-ism rather than a DOS-ism, but
that might just be splitting hairs...

> -> However, there is some room for interpretation of what exactly
> -> "compatibility area of RAM" where the ROMs get copied to really means.
> -> According to the spec, it is "typically 0C0000h to 0E0000h", but is it
> -> really only that on x86 PC's?
> 
> Yes. See para 6.3.3, PCI SPec 2.1.

I think that my last sentence is poorly worded, causing some confusion.  In
section 6.3.3 of the PCI spec 2.1, it states that the locations which the
ROMs are copied to is "typically 0C0000h to 0E0000h", but it doesn't mandate
that they be located there, does it?  In particular, could the system BIOS
use a different memory range, or a larger space, if it was willing to eat
up that space from OS use?

> -> A much better solution, in my mind, would be to simply try to make a
> -> smaller ROM (which, I admit may not always be possible.)
> 
> An even better solution is to let 'em have any size ROM they want. This
> means getting rid of vestigial Mess-DOS-isms, of course.

Sure, if you don't care if your card works in a DOS system, then you can have
an size ROM you want.  (And you'd probably want to have an OpenFirmware ROM
instead of a x86 binary ROM anyway, right...)

But, if you want your card to work in a DOS system, then you have to live
with the limitations of that system.  The original poster was designing cards
intended for use in a PC platform and then complaining that the evil BIOSes
of the world were conspiring against him when he was doing things that seemed,
in my opinion, on the edge of respectability.

-Richard Walter
rwalter@auspex.com
Note: I speak for myself, not for Auspex.

TA