xref: /freebsd/share/man/man9/pmap_extract.9 (revision 74bf4e164ba5851606a27d4feff27717452583e5)
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26.\" $FreeBSD$
27.\"
28.Dd July 21, 2003
29.Dt PMAP_EXTRACT 9
30.Os
31.Sh NAME
32.Nm pmap_extract ,
33.Nm pmap_extract_and_hold
34.Nd map a virtual address to a physical page
35.Sh SYNOPSIS
36.In sys/param.h
37.In vm/vm.h
38.In vm/pmap.h
39.Ft vm_paddr_t
40.Fn pmap_extract "pmap_t pmap" "vm_offset_t va"
41.Ft vm_paddr_t
42.Fn pmap_extract_and_hold "pmap_t pmap" "vm_offset_t va" "vm_prot_t prot"
43.Sh DESCRIPTION
44The
45.Fn pmap_extract
46function maps a virtual address to a physical page.
47In certain situations, callers may use
48.Fn pmap_extract_and_hold
49instead, to ensure that the returned page is held.
50.Pp
51The
52.Fn pmap_extract_and_hold
53function maps a virtual address to a physical page, and atomically holds
54the returned page for use by the caller, only if the mapping permits
55the given page protection.
56.Sh IMPLEMENTATION NOTES
57Currently, the page protection requested by the caller is not verified.
58.Pp
59In the
60.Fn pmap_extract_and_hold
61function, the
62.Va Giant
63lock is held for the duration of the call to ensure that only a single
64caller is present.
65.Sh RETURN VALUES
66The
67.Fn pmap_extract
68function will return the physical page address associated with the
69virtual address
70.Fa va
71inside the physical map
72.Fa pmap .
73If the mapping does not exist, or if the
74.Fa pmap
75parameter is
76.Dv NULL ,
77then
78.Dv NULL
79will be returned.
80.Pp
81The
82.Fn pmap_extract_and_hold
83function will return the physical page address associated with the
84virtual address
85.Fa va
86inside the physical map
87.Fa pmap .
88If the mapping does not exist, the result is a no-op, and
89.Dv NULL
90will
91be returned.
92.Sh SEE ALSO
93.Xr mutex 9 ,
94.Xr pmap 9
95.Sh AUTHORS
96.An -nosplit
97The
98.Fn pmap_extract_and_hold
99function was implemented by
100.An Alan L. Cox Aq alc@imimic.com .
101This manual page was written by
102.An Bruce M Simpson Aq bms@spc.org .
103