> > currently, the MD part deals with some allocation policies,
> > eg. preferablly allocate buffers from DMAable memory.
> > how do you think about it?
> > i guess "file" page caches can use the same or similar mechanism.
> 
> The remnants of such things that I have seen sofar (e.g. on alpha)
> don't make much sense to me. The "special" memory passed to allocsys()
> on some platforms is only used to allocate the `buf' array itself, which
> need not be `DMAable'.

at least, i386 allocates pages for buffer cache with VM_FREELIST_FIRST16.

YAMAMOTO Takashi