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davem@dm.cobaltmicro.com said: > On the 64-bit architectures I know of, and PCI as specified, is not > limited to 64-bits of physical addressing. I think you meant 32bits? PCI *is* limited to 64bits, but not 32:-) Well, the 32bit PCI supports 64bit addresses with the dual address cycle, but that adds a clock cycle to the PCI transaction, which would best be avoided. Longer bursts can amortize that cost away pretty quickly, but it is there all the same. Unfortunately, the GFP_DMA bit is getting to be overloaded. I'm going to make the ugly suggestion that there be added a variant of get_free_pages that can be compelled to allocate pages from specific regions. One can make that extra parameter the address size (in bits) and this should work well with a buddy-system allocator. I can hope 64bit PCI will come of age in time to save us (I know that my alpha has a couple 64bit PCI slots in it) but I'm afraid I know better:-) -- Steve Williams "The woods are lovely, dark and deep. steve@icarus.com But I have promises to keep, steve@picturel.com and lines to code before I sleep, http://www.picturel.com And lines to code before I sleep." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu | ||||||||||||
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