most (all i know of) of the EV5 and up (maybe pre-EV5 aswell) machines are
real nice. From the 21172/21174 doc's, it seems it works very much like CPU
page lookups. AFAIK The chipset stores a map table in a page in RAM, and has
a pinnable 8 entry TLB.
Very advanced stuff. Potential to solve any type of bus->phys mapping
problem. And would allow large memory on Alpha without needing zones, and
any bus device could DMA to/from anywhere in RAM without needing bounce
buffers. But we don't use it yet.
> This would be good for low end devices that don't do scatter/gather
> themselves - I seem to remember some of the frame grabber ones have
> this problem.
>
Even for scatter-gather capable hardware it would be a win. Chipset
scatter-gather would allow them to access any RAM. Irregardless of how much
memory is in the machine.
> Right, this should of course be combined with generic scatter/gather
> support in important places like the skbuffs (through the use of
> kiobufs). Some well designed hardware (like some modern network cards)
> already supports this .... and it would solve a lot of problems for
> the HIPPI and Fibre Channel drivers.
>
generic scatter-gather interface would be nice. Alpha would really benefit
from it.
> Jes
>
-paul jakma.
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