103 lines
3.1 KiB
Groff
103 lines
3.1 KiB
Groff
.\"
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.\" Copyright (c) 2003 Bruce M Simpson <bms@spc.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 21, 2003
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.Dt PMAP_EXTRACT 9
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.Os
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.Sh NAME
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.Nm pmap_extract ,
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.Nm pmap_extract_and_hold
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.Nd map a virtual address to a physical page
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.Sh SYNOPSIS
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.In sys/param.h
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.In vm/vm.h
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.In vm/pmap.h
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.Ft vm_paddr_t
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.Fn pmap_extract "pmap_t pmap" "vm_offset_t va"
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.Ft vm_paddr_t
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.Fn pmap_extract_and_hold "pmap_t pmap" "vm_offset_t va" "vm_prot_t prot"
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.Sh DESCRIPTION
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The
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.Fn pmap_extract
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function maps a virtual address to a physical page.
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In certain situations, callers may use
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.Fn pmap_extract_and_hold
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instead, to ensure that the returned page is held.
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.Pp
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The
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.Fn pmap_extract_and_hold
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function maps a virtual address to a physical page, and atomically holds
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the returned page for use by the caller, only if the mapping permits
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the given page protection.
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.Sh IMPLEMENTATION NOTES
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Currently, the page protection requested by the caller is not verified.
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.Pp
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In the
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.Fn pmap_extract_and_hold
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function, the
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.Va Giant
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lock is held for the duration of the call to ensure that only a single
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caller is present.
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.Sh RETURN VALUES
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The
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.Fn pmap_extract
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function will return the physical page address associated with the
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virtual address
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.Fa va
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inside the physical map
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.Fa pmap .
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If the mapping does not exist, or if the
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.Fa pmap
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parameter is
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.Dv NULL ,
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then
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.Dv NULL
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will be returned.
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.Pp
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The
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.Fn pmap_extract_and_hold
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function will return the physical page address associated with the
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virtual address
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.Fa va
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inside the physical map
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.Fa pmap .
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If the mapping does not exist, the result is a no-op, and
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.Dv NULL
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will
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be returned.
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.Sh SEE ALSO
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.Xr mutex 9 ,
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.Xr pmap 9
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.Sh AUTHORS
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.An -nosplit
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The
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.Fn pmap_extract_and_hold
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function was implemented by
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.An Alan L. Cox Aq alc@imimic.com .
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This manual page was written by
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.An Bruce M Simpson Aq bms@spc.org .
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