pmap_extract(9)

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.

IMPLEMENTATION NOTES

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.

RETURN VALUES

The pmap_extract() function will return the physical page

address associated 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 physi

cal 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.

SEE ALSO

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>.

BSD July 21, 2003

BSD