The problem is that the only thing you can't do (except for on a
Sparc (#) ) is solve DMA problems.
> DMA memory could be allocated by moving allocated blocks away from the
> lower 16MB, and other parts of kernel could be made happy by changing the
> page tables accordingly.
Yeah. Another part of the kernel might still be having a "physical"
pointer to that memory because some other device is going to DMA
into that memory.
> So, is this possible/feasible/too ugly to implement?
Yeah. Too ugly.
Roger.
(#) Many sparcs use the SBUS which has "DVMA", Direct Virtual Memory
Access: They go through the MMU for DMA accesses.......