Rob Landley wrote in a message to John Poltorak:

 RL> 32 bit DMA can access all memory, but older cards with 16
 RL> bit DMA can only access the first 16 megs, which is why OS/2
 RL> will only use memory above 16 megs for swap space if any of
 RL> your cards use 16 bit DMA.

That's not quite right.  The driver for the card is at fault, not the card.
 When the driver calls kernel helper services to lock memory for doing DMA,
it can specifically request that the lock occur below the 16 MB boundary if
necessary for the particular hardware.  If the driver is smart enough to do
that, then it can signal to the operating system that it supports memory
greater than 16 MB because it takes the proper precautions with locating
its DMA buffers.  Other than for DMA, this is really not an issue.
 
-- Mike


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