pmap_extract_and_hold (9)

Leading comments

Copyright (c) 2003 Bruce M Simpson <bms@spc.org>
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(The comments found at the beginning of the groff file "man9/pmap_extract_and_hold.9freebsd".)

NAME

pmap_extract pmap_extract_and_hold - map a virtual address to a physical page

SYNOPSIS

In sys/param.h In vm/vm.h In vm/pmap.h Ft vm_paddr_t Fn pmap_extract pmap_t pmap vm_offset_t va Ft vm_paddr_t Fn pmap_extract_and_hold pmap_t pmap vm_offset_t va vm_prot_t prot

DESCRIPTION

The Fn pmap_extract function maps a virtual address to a physical page. In certain situations, callers may use Fn pmap_extract_and_hold instead, to ensure that the returned page is held.

The Fn 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.

RETURN VALUES

The Fn pmap_extract function will return the physical page address associated with the virtual address Fa va inside the physical map Fa pmap . If the mapping does not exist, or if the Fa pmap parameter is NULL then NULL will be returned.

The Fn pmap_extract_and_hold function will return the physical page address associated with the virtual address Fa va inside the physical map Fa 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

An -nosplit The Fn pmap_extract_and_hold function was implemented by An Alan L. Cox Aq alc@imimic.com . This manual page was written by An Bruce M Simpson Aq bms@spc.org .