Max DMA size

[Zhihui Zhang]

Can anyone tell me what factors determine the max DMA size (DMA counter on
each controller or PCI bus related)? What is the typical max DMA size for
a SCSI disk connected to a PCI bus? It seems to be much larger than
MAXPHYS (128K). If so, does it mean we are not using full potential of
DMA? So what's the problem if we enlarge MAXPHYS?

Any help is appreciated.

-Zhihui



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