Given that my 64-bit machines are often equiped with memory amounts
counted in gigabytes; sometimes exceeding 4 GB, and as the 32-bit PCI
devices can address "only" up to 4G, there is a problem.
(My largest 64-bit Linux box has 0.5G memory.)
I think we will be needing GFP_DMA32 soon.
(And it will cause *massive* amounts of changes as practically all
drivers will need touching...)
DaveM can tell us how the large SPARC64 systems do it with their heaps
of busses and address spaces. I recall SPARCs have IO-MMU, which may
help in this regard. Large-scale DEC systems have similar gimmics
in their IO controllers mapping 32-bit IO busses to 43-bit cpu/memory
interconnect busses (43 address bits, that is).
/Matti Aarnio <matti.aarnio@sonera.fi>
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