> 	Should I be building my kernels with MACHINE_NONCONTIG enabled?
> 	If so, should the default config files have it set?

Both work. A `MACHINE_NONCONTIG' kernel is slightly more efficient on (locked
down) kernel memory.

> 	If not... why was it all added a while back :)
> 

It takes advantage of the `non-contig' support in the VM system, instead of
handling "VM physical" <=> "hardware physical" translations in the pmap
module. The latter worked with statically allocated tables which posed an
upper limit on the amount of physical memory that could be handled.

`MACHINE_NONCONTIG' will be the default for the sparc port soon.

-pk