Provided by:
freebsd-manpages_6.2-1_all 
NAME
pmap_extract, pmap_extract_and_hold - map a virtual address to a physical
page
SYNOPSIS
#include <sys/param.h>
#include <vm/vm.h>
#include <vm/pmap.h>
vm_paddr_t
pmap_extract(pmap_t pmap, vm_offset_t va);
vm_paddr_t
pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot);
DESCRIPTION
The pmap_extract() function maps a virtual address to a physical page.
In certain situations, callers may use pmap_extract_and_hold() instead,
to ensure that the returned page is held.
The pmap_extract_and_hold() function maps a virtual address to a physical
page, and atomically holds the returned page for use by the caller, only
if the mapping permits the given page protection.
Currently, the page protection requested by the caller is not verified.
In the pmap_extract_and_hold() function, the Giant lock is held for the
duration of the call to ensure that only a single caller is present.
The pmap_extract() function will return the physical page address associ‐
ated with the virtual address va inside the physical map pmap. If the
mapping does not exist, or if the pmap parameter is NULL, then NULL will
be returned.
The pmap_extract_and_hold() function will return the physical page
address associated with the virtual address va inside the physical map
pmap. If the mapping does not exist, the result is a no-op, and NULL
will be returned.
mutex(9), pmap(9)
AUTHORS
The pmap_extract_and_hold() function was implemented by Alan L. Cox
〈alc@imimic.com〉. This manual page was written by Bruce M Simpson
〈bms@spc.org〉.