Let me clarify.

1) NEW_PIPE was broken on port-mips.
2) the cause of the problem is virtual alias.
3) cache flush was added to pmap.c(rev. 1.142).
4) pmap.c(1.142) did not eliminate virtual alias.
5) sys_pipe.c should not call pmap_enter().
6) pmap_kenter_pv() should not call pmap_enter_pv().
7) NEW_PIPE is still broken on port-mips.
8) to workaround this problem, port-mips with VACs should use
   'options PIPE_SOCKETPAIR'.

If there is any misunderstanding, please correct.

--- Takao Shinohara