is this intended to continue to be compilable and runnable on a pdp/11.

[cm68]

it sure would be nice to get NFS running on a pdp-11, but it's not at all clear that this is intended.

[TheSledgeHammer]

PDP-11 compatibility wouldn't be possible, due to PDP-11 memory constraints and that unlike the original 2.11BSD which is 16-bit, 2.11BSD_X44 is 32/64-bit.
The aforementioned point may also cause problems even if I said it might be possible to backport nfs to the original 2.11BSD.
However hardware compatibility with the tape drives, hard drives and the like is definitely possible if desired with porting.
It also is possible to port it to something like VAX and the pdp-10.