Copyright (c) 2003 Bruce M Simpson <bms@spc.org>
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$FreeBSD$

.Dd July 21, 2003 .Dt PMAP_EXTRACT 9 .Os .Sh NAME .Nm pmap_extract , .Nm pmap_extract_and_hold .Nd map a virtual address to a physical page .Sh SYNOPSIS n sys/param.h n vm/vm.h n 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" .Sh 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.

p 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. .Sh IMPLEMENTATION NOTES Currently, the page protection requested by the caller is not verified. .Sh 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 .Dv NULL , then .Dv NULL will be returned.

p 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 .Dv NULL will be returned. .Sh SEE ALSO .Xr mutex 9 , .Xr pmap 9 .Sh 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 .