Re: regression fixed by using pci=rom

[Gary Hade <garyhade@us.ibm.com>]

On Fri, May 09, 2008 at 10:26:47AM -0700, Linus Torvalds wrote:
> 
> 
> On Fri, 9 May 2008, Gary Hade wrote:
> > 
> > Ingo, Would you (or others listening to this discussion) know
> > exactly what Windows does with respect to BIOS unassigned
> > expansion ROMs?
> 
> Nobody really seems to know what windows does for *any* resources. And it 
> probably depends on windows version too, and on detailed chipset issues 
> (ie does Windows do the same thing as Linux wrt transparent bridges that 
> still have bus translation resources set up?).
> 
> So the "try to do what Windows does" is something we strive for in 
> particular cases, but it's not an absolute thing, and probably can never 
> even be that in theory. It's more a guideline, especially when we don't 
> know which particular choice is better and both seem otherwise equally 
> good.
> 
> But "doesn't work" always trumps "that's what windows does". Because even 
> if something works under Windows, sometimes Linux drivers simply then act 
> differently (ie they may use PIO vs MMIO, or in the case of graphics they 
> may need ROMs for re-POST'ing while a windows driver is written by the 
> chipset vendor and DTRT without even looking at the BIOS tables)

Yea, this is probably a good explanation of why Windows does run,
presumably without PCI resource allocation issues, on those same
systems where we have struggling with the expansion ROM resource
allocation failures from Linux.

Thanks.

Gary

-- 
Gary Hade
System x Enablement
IBM Linux Technology Center
503-578-4503  IBM T/L: 775-4503
garyhade@us.ibm.com
http://www.ibm.com/linux/ltc