Since prefetchable memory is not beeing allocated correctly behind PCI-to-PCI bridges, this is a work-around to make it possible to uses devices located behind PCI-bridges. E.g. the Matrox G450 now works since prefetchable PCI memory is completly disabled.

I saw some very promissing patches from Russel some where around december on the mailing list that bring the behaviour of /driver/pci/setup-bus.c in line with prefetchable memory support for devices on PCI bus 00. This patch was adding a member for prefetchable memory regions to 
	struct pbus_set_ranges_data
	{
	        int found_vga;
	        unsigned long io_start, io_end;
	        unsigned long mem_start, mem_end;
	};
used in through-bridge resource allocations. 

Russel, do you think your patch could solve the problem more elegant?

In addition, I changed some comments and introduced defines from platform.h instead of hard-code values.