In article <D5B84001-8536-4933-B85B-5E67019A0334@microsoft.com>, =?Utf-
8?B?TG91IFJvaGFu?= <Lou Rohan@discussions.microsoft.com> says...

Your example is a bit extreme, and as others have noted, the bridge
under which this device sits may have a bit of a problem with supporting
the bar's allocation, and even if the bridge can manage it there may not
be enough mappable system address space for the range.

In a less extreme example, where a bar presents a range of host-
accessible device memory of a reasonable size, but much larger than
actually needed, it is a common technique to only map into virtual
memory the size needed by the driver, rather than the entire range
declared by the bar.

Hardware/firmware that support a window mechanism is much more friendly
to virtual memory resource allocation on host systems.

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Mark Roddy DDK MVP
Windows 2003/XP/2000 Consulting
Hollis Technology Solutions 603-321-1032
www.hollistech.com
markr@hollistech.com