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.\" $FreeBSD$ 28.\" 29.Dd August 31, 2011 30.Dt VM_PAGE_AFLAG 9 31.Os 32.Sh NAME 33.Nm vm_page_aflag_clear , vm_page_aflag_set , vm_page_reference 34.Nd "change page atomic flags" 35.Sh SYNOPSIS 36.In sys/param.h 37.In vm/vm.h 38.In vm/vm_page.h 39.Ft void 40.Fn vm_page_aflag_clear "vm_page_t m" "uint8_t bits" 41.Ft void 42.Fn vm_page_aflag_set "vm_page_t m" "uint8_t bits" 43.Ft void 44.Fn vm_page_reference "vm_page_t m" 45.Sh DESCRIPTION 46The 47.Fn vm_page_aflag_clear 48atomically clears the specified bits on the page's 49.Va aflags . 50.Pp 51The 52.Fn vm_page_aflag_set 53atomically sets the specified bits on the page's 54.Va aflags . 55.Pp 56The 57.Fn vm_page_reference m 58call is the same as 59.Bd -literal -offset indent 60vm_page_aflag_set(m, PGA_REFERENCED); 61.Ed 62.Lp 63and is the recommended way to mark the page as referenced from 64third-party kernel modules. 65.Pp 66These functions neither block nor require any locks to be held 67around the calls for correctness. 68.Pp 69The functions arguments are: 70.Bl -tag -width ".Fa bits" 71.It Fa m 72The page whose 73.Va aflags 74are updated. 75.It Fa bits 76The bits that are set or cleared on the page's flags. 77.El 78.Pp 79The following 80.Va aflags 81can be set or cleared: 82.Bl -tag -width ".Fa PGA_REFERENCED" 83.It Fa PGA_REFERENCED 84The bit may be set to indicate that the page has been recently accessed. 85For instance, 86.Xr pmap 9 87sets this bit to reflect the accessed attribute of the page mapping 88typically updated by processor's memory management unit on the page access. 89.It Fa PGA_WRITEABLE 90A writeable mapping for the page may exist. 91.El 92.Pp 93Both 94.Dv PGA_REFERENCED 95and 96.Dv PGA_WRITEABLE 97bits are only valid for the managed pages. 98.Sh AUTHORS 99This manual page was written by 100.An Chad David Aq davidc@acns.ab.ca . 101