the "bad" aliases we're generating now should not cause any problems,
because all mappings of loaned pages are read-only and thus safe to cache
if all the changes made to the page before the page is loaned are flushed
to main memory when the loan is created.  that's why the cache flush in
pmap_protect() fixes the problem.  are you sure NEW_PIPE still has
problems on mips?

-Chuck


On Sun, Mar 24, 2002 at 03:50:21PM +0900, Takao Shinohara wrote:
> 
> 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