The Future - Buffer Flipping



Device accessibility (amd64 - with drivers that can only access 32 bits of memory)
Allocate buffers in device accessible memory
Allow buffers to move to other unused memory (flip to high memory). - older buffers end up in high memory. 
If we need to do IO, bring back into DMA accessible memory. 
Can use more memory without need for bounce buffer in drivers.

Probably in OpenBSD 5.4.