Messages in this thread | | | Subject | Re: [Linux-ia64] patch to no longer use ia64's software mmu | Date | Tue, 4 Dec 2001 17:18:17 +0000 (GMT) | From | Alan Cox <> |
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> I think the issue at hand is whether, longer term, it is desirable to > move all bounce buffer handling into the PCI DMA layer or whether > Linux should continue to make bounce buffer management visible to > drivers. I'd be interested in hearing opinions.
I think the performance figures we see currently answer that already. Bounce management in a sense is PCI layer, but its PCI layer in the sense of helpers called by subsystems or devices not as a global layer in the middle.
On a box with 32bit limited cards you need to do zone stuff and play with the high zone even though your kmap is a nop. It's not ideal but its the real world. IA64 also needs to correct its GFP_DMA to mean "low 16Mb" for ISA DMA. While there is no ISA DMA on ia64 (thankfully) many PCI cards have 26-31 bit limits.
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