xref: /freebsd/share/man/man9/pmap_extract.9 (revision 1772ac3f492e9cefc36c05794c38b54c7069f22b)
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26.\" $FreeBSD$
27.\"
28.Dd July 21, 2003
29.Dt PMAP_EXTRACT 9
30.Sh NAME
31.Nm pmap_extract ,
32.Nm pmap_extract_and_hold
33.Nd map a virtual address to a physical page
34.Sh SYNOPSIS
35.In sys/param.h
36.In vm/vm.h
37.In vm/pmap.h
38.Ft vm_paddr_t
39.Fn pmap_extract "pmap_t pmap" "vm_offset_t va"
40.Ft vm_paddr_t
41.Fn pmap_extract_and_hold "pmap_t pmap" "vm_offset_t va" "vm_prot_t prot"
42.Sh DESCRIPTION
43The
44.Fn pmap_extract
45function maps a virtual address to a physical page.
46In certain situations, callers may use
47.Fn pmap_extract_and_hold
48instead, to ensure that the returned page is held.
49.Pp
50The
51.Fn pmap_extract_and_hold
52function maps a virtual address to a physical page, and atomically holds
53the returned page for use by the caller, only if the mapping permits
54the given page protection.
55.Sh IMPLEMENTATION NOTES
56Currently, the page protection requested by the caller is not verified.
57.Pp
58In the
59.Fn pmap_extract_and_hold
60function, the
61.Va Giant
62lock is held for the duration of the call to ensure that only a single
63caller is present.
64.Sh RETURN VALUES
65The
66.Fn pmap_extract
67function will return the physical page address associated with the
68virtual address
69.Fa va
70inside the physical map
71.Fa pmap .
72If the mapping does not exist, or if the
73.Fa pmap
74parameter is
75.Dv NULL ,
76then
77.Dv NULL
78will be returned.
79.Pp
80The
81.Fn pmap_extract_and_hold
82function will return the physical page address associated with the
83virtual address
84.Fa va
85inside the physical map
86.Fa pmap .
87If the mapping does not exist, the result is a no-op, and
88.Dv NULL
89will
90be returned.
91.Sh SEE ALSO
92.Xr mutex 9 ,
93.Xr pmap 9
94.Sh AUTHORS
95.An -nosplit
96The
97.Fn pmap_extract_and_hold
98function was implemented by
99.An Alan L. Cox Aq alc@imimic.com .
100This manual page was written by
101.An Bruce M Simpson Aq bms@spc.org .
102