1.\" 2.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as 9.\" the first lines of this file unmodified other than the possible 10.\" addition of one or more copyright notices. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice(s), this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 16.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 19.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 20.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 22.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 25.\" DAMAGE. 26.\" 27.Dd August 31, 2011 28.Dt VM_PAGE_AFLAG 9 29.Os 30.Sh NAME 31.Nm vm_page_aflag_clear , vm_page_aflag_set , vm_page_reference 32.Nd "change page atomic flags" 33.Sh SYNOPSIS 34.In sys/param.h 35.In vm/vm.h 36.In vm/vm_page.h 37.Ft void 38.Fn vm_page_aflag_clear "vm_page_t m" "uint8_t bits" 39.Ft void 40.Fn vm_page_aflag_set "vm_page_t m" "uint8_t bits" 41.Ft void 42.Fn vm_page_reference "vm_page_t m" 43.Sh DESCRIPTION 44The 45.Fn vm_page_aflag_clear 46atomically clears the specified bits on the page's 47.Va aflags . 48.Pp 49The 50.Fn vm_page_aflag_set 51atomically sets the specified bits on the page's 52.Va aflags . 53.Pp 54The 55.Fn vm_page_reference m 56call is the same as 57.Bd -literal -offset indent 58vm_page_aflag_set(m, PGA_REFERENCED); 59.Ed 60.Lp 61and is the recommended way to mark the page as referenced from 62third-party kernel modules. 63.Pp 64These functions neither block nor require any locks to be held 65around the calls for correctness. 66.Pp 67The functions arguments are: 68.Bl -tag -width ".Fa bits" 69.It Fa m 70The page whose 71.Va aflags 72are updated. 73.It Fa bits 74The bits that are set or cleared on the page's flags. 75.El 76.Pp 77The following 78.Va aflags 79can be set or cleared: 80.Bl -tag -width ".Fa PGA_REFERENCED" 81.It Fa PGA_REFERENCED 82The bit may be set to indicate that the page has been recently accessed. 83For instance, 84.Xr pmap 9 85sets this bit to reflect the accessed attribute of the page mapping 86typically updated by processor's memory management unit on the page access. 87.It Fa PGA_WRITEABLE 88A writeable mapping for the page may exist. 89.El 90.Pp 91Both 92.Dv PGA_REFERENCED 93and 94.Dv PGA_WRITEABLE 95bits are only valid for the managed pages. 96.Sh AUTHORS 97This manual page was written by 98.An Chad David Aq Mt davidc@acns.ab.ca . 99