Messages in this thread | | | Subject | Re: [parisc-linux] Untested port of parisc_device to generic device interface | Date | Wed, 13 Nov 2002 15:21:07 -0500 | From | "J.E.J. Bottomley" <> |
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Miles Bader wrote: > I can't speak for `real machines,' but on my wierd embedded board, > pci_alloc_consistent allocates from a special area of memory (not > located at 0) that is the only shared memory between PCI devices and the > CPU. pci_alloc_consistent happens to fit this situation quite well, but > I don't think a bitmask is enough to express the situation.
grundler@dsl2.external.hp.com said: > HP PARISC V-Class do that as well. The "consistent" memory lives on > the PCI Bus Controller - not in host mem. Note that parisc-linux does > not (yet) support V-class.
Actually, I think dma_mask and consistent memory are orthogonal problems. dma_masks are used by the I/O subsystem to determine whether direct DMA to a memory region containing an I/O buffer is possible or whether it has to be bounced. Consistent memory is usually allocated for driver specific transfers. The I/O subsystem doesn't usually require the actual I/O buffers to be in consistent memory.
James
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