I've made some test in linux Intel and PPC. The only way to have a defined
virtual memory ptr is to use
ioremap on an Intel box. On Linux PPC ioremap returns 0 sometimes, or
otherwise returns a pointer
without doing any PCI memory to physical memory conversion (is this correct
? And don't know the
real goal of ioremap: remapping only I/O or something more global ). On
Linux PPC bus_to_virt() alone
yield a defined virtual memory pointer (virtual memory is preallocated in
bats registers), but on an Intel
Box this method is not usabled these memory range are not defined in the
MMU.
The correct method is probably to do a bus_to_virt followed by an ioremap ?
If you have an accurate definition of these function compatible with all
linux architecture (Intel, PPC, ...)
let me know.
(There is some explaination in file 'linux/Documentation/IO-mapping.txt' but
the PCI memory
mapping is not precisely describe in a working way)
> Patrick LERDA
>
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