> 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.
Alan
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This archive was generated by hypermail 2b29 : Fri Dec 07 2001 - 21:00:24 EST