Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice(s), this list of conditions and the following disclaimer as
the first lines of this file unmodified other than the possible
addition of one or more copyright notices.
2. Redistributions in binary form must reproduce the above copyright
notice(s), this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
DAMAGE.

$FreeBSD$

.Dd August 31, 2011 .Dt VM_PAGE_AFLAG 9 .Os .Sh NAME .Nm vm_page_aflag_clear , vm_page_aflag_set , vm_page_reference .Nd "change page atomic flags" .Sh SYNOPSIS n sys/param.h n vm/vm.h n vm/vm_page.h .Ft void .Fn vm_page_aflag_clear "vm_page_t m" "uint8_t bits" .Ft void .Fn vm_page_aflag_set "vm_page_t m" "uint8_t bits" .Ft void .Fn vm_page_reference "vm_page_t m" .Sh DESCRIPTION The .Fn vm_page_aflag_clear atomically clears the specified bits on the page's .Va aflags .

p The .Fn vm_page_aflag_set atomically sets the specified bits on the page's .Va aflags .

p The .Fn vm_page_reference m call is the same as d -literal -offset indent vm_page_aflag_set(m, PGA_REFERENCED); .Ed .Lp and is the recommended way to mark the page as referenced from third-party kernel modules.

p These functions neither block nor require any locks to be held around the calls for correctness.

p The functions arguments are: l -tag -width ".Fa bits" t Fa m The page whose .Va aflags are updated. t Fa bits The bits that are set or cleared on the page's flags. .El

p The following .Va aflags can be set or cleared: l -tag -width ".Fa PGA_REFERENCED" t Fa PGA_REFERENCED The bit may be set to indicate that the page has been recently accessed. For instance, .Xr pmap 9 sets this bit to reflect the accessed attribute of the page mapping typically updated by processor's memory management unit on the page access. t Fa PGA_WRITEABLE A writeable mapping for the page may exist. .El

p Both .Dv PGA_REFERENCED and .Dv PGA_WRITEABLE bits are only valid for the managed pages. .Sh AUTHORS This manual page was written by .An Chad David Aq davidc@acns.ab.ca .