The ISA limit is actually at 16MB for what that's worth. PCI devices should
be able to address the entire 32-bit space.
To answer something you mentioned in an earlier message, the "virtual DMA"
that the floppy driver uses isn't really DMA at all. Instead the driver
performs the data transfer itself using inb and outb instructions to the FDC.
This is why it can get away with a buffer allocated with vmalloc; it's never
addressed by any hardware directly. Some of the low end SCSI hosts do similar
tricks.
p.
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