Add a special page zero entry point intended to be called via the single

threaded VM pagezero kthread outside of Giant.  For some platforms, this
is really easy since it can just use the direct mapped region.  For others,
IPI sending is involved or there are other issues, so grab Giant when
needed.

We still have preemption issues to deal with, but Alan Cox has an
interesting suggestion on how to minimize the problem on x86.

Use Luigi's hack for preserving the (lack of) priority.

Turn the idle zeroing back on since it can now actually do something useful
outside of Giant in many cases.

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/vm/pmap.h b/sys/vm/pmap.h
index 79a73f6..23e3c43 100644
--- a/sys/vm/pmap.h
+++ b/sys/vm/pmap.h
@@ -126,6 +126,7 @@ void		 pmap_remove(pmap_t, vm_offset_t, vm_offset_t);
 void		 pmap_remove_pages(pmap_t, vm_offset_t, vm_offset_t);
 void		 pmap_zero_page(vm_page_t);
 void		 pmap_zero_page_area(vm_page_t, int off, int size);
+void		 pmap_zero_page_idle(vm_page_t);
 void		 pmap_prefault(pmap_t, vm_offset_t, vm_map_entry_t);
 int		 pmap_mincore(pmap_t pmap, vm_offset_t addr);
 void		 pmap_new_thread(struct thread *td);