Its a very bad idea to start assuming nbit. It isnt that simple as chips
may have memory windows. GFP_ISADMA maybe.
> Machines with ISA Olicom cards, often run out of DMA memory. We really
> want to allocate a new buffer on every packet that comes in. That way
Sounds odd. You want to write tr_copy_and_checksum(). THe copy from the
DMA ram to main memory (and more importantly L1 cache) has the same cost
as the later checksum pass so you can do that instead of sucking up DMA
memory.
> breaking down. Now, there have been improvements in this area, but
> it sure was tricky to get right....
There are reasons that dev_alloc_skb() has no provision to force ISA memory.
You end up with it failing, with sound cards unable to load and other bad
stuff if you go allocating skbuffs from ISA pools
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