Previously, pvzone's initialization was split between pmap_init() and
pmap_init2(). This split initialization was the underlying cause of
some UMA panics during initialization. Specifically, if the UMA boot
pages was exhausted before the pvzone was fully initialized, then UMA,
through no fault of its own, would use an inappropriate back-end
allocator leading to a panic. (Previously, as a workaround, we have
increased the UMA boot pages.) Fortunately, there is no longer any
reason that pvzone's initialization cannot be completed in
pmap_init().
Eliminate a check for whether pv_entry_high_water has been initialized
or not from get_pv_entry(). Since pvzone's initialization is
completed in pmap_init(), this check is no longer needed.
Use cnt.v_page_count, the actual count of available physical pages,
instead of vm_page_array_size to compute the maximum number of pv
entries.
Introduce the vm.pmap.pv_entries tunable on alpha and ia64.
Eliminate some unnecessary white space.
Discussed with: tegge (item #1)
Tested by: marcel (ia64)
e9cb1037da