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 December 1, 2001 30.Dt VM_PAGE_BITS 9 31.Os 32.Sh NAME 33.Nm vm_page_bits , 34.Nm vm_page_set_validclean , 35.Nm vm_page_clear_dirty , 36.Nm vm_page_set_invalid , 37.Nm vm_page_zero_invalid , 38.Nm vm_page_is_valid , 39.Nm vm_page_test_dirty , 40.Nm vm_page_dirty , 41.Nm vm_page_undirty 42.Nd "manage page clean and dirty bits" 43.Sh SYNOPSIS 44.In sys/param.h 45.In vm/vm.h 46.In vm/vm_page.h 47.Ft int 48.Fn vm_page_bits "int base" "int size" 49.Ft void 50.Fn vm_page_set_validclean "vm_page_t m" "int base" "int size" 51.Ft void 52.Fn vm_page_clear_dirty "vm_page_t m" "int base" "int size" 53.Ft void 54.Fn vm_page_set_invalid "vm_page_t m" "int base" "int size" 55.Ft void 56.Fn vm_page_zero_invalid "vm_page_t m" "boolean_t setvalid" 57.Ft int 58.Fn vm_page_is_valid "vm_page_t m" "int base" "int size" 59.Ft void 60.Fn vm_page_test_dirty "vm_page_t m" 61.Ft void 62.Fn vm_page_dirty "vm_page_t m" 63.Ft void 64.Fn vm_page_undirty "vm_page_t m" 65.Sh DESCRIPTION 66.Fn vm_page_bits 67calculates the bits representing the 68.Dv DEV_BSIZE 69range of bytes between 70.Fa base 71and 72.Fa size . 73The byte range is expected to be within a single page, and if 74.Fa size 75is zero, no bits will be set. 76.Pp 77.Fn vm_page_set_validclean 78flags the byte range between 79.Fa base 80and 81.Fa size 82as valid and clean. 83The range is expected to be 84.Dv DEV_BSIZE 85aligned and no larger than 86.Dv PAGE_SIZE . 87If it is not properly aligned, any unaligned chucks of the 88.Dv DEV_BSIZE 89blocks at the beginning and end of the range will be zeroed. 90.Pp 91If 92.Fa base 93is zero and 94.Fa size 95is one page, the modified bit in the page map is cleared; as well, 96the 97.Dv PG_NOSYNC 98flag is cleared. 99.Pp 100.Fn vm_page_clear_dirty 101clears the dirty bits within a page in the range between 102.Fa base 103and 104.Fa size . 105The bits representing the range are calculated by calling 106.Fn vm_page_bits . 107.Pp 108.Fn vm_page_set_invalid 109clears the bits in both the valid and dirty flags representing 110the 111.Dv DEV_BSIZE 112blocks between 113.Fa base 114and 115.Fa size 116in the page. 117The bits are calculated by calling 118.Fn vm_page_bits . 119As well as clearing the bits within the page, the generation 120number within the object holding the page is incremented. 121.Pp 122.Fn vm_page_zero_invalid 123zeroes all of the blocks within the page that are currently 124flagged as invalid. 125If 126.Fa setvalid 127is 128.Dv TRUE , 129all of the valid bits within the page are set. 130.Pp 131In some cases, such as NFS, the valid bits cannot be set 132in order to maintain cache consistency. 133.Pp 134.Fn vm_page_is_valid 135checks to determine if the all of the 136.Dv DEV_BSIZE 137blocks between 138.Fa base 139and 140.Fa size 141of the page are valid. 142If 143.Fa size 144is zero and the page is entirely invalid 145.Fn vm_page_is_valid 146will return 147.Dv TRUE , 148in all other cases a size of zero will return 149.Dv FALSE . 150.Pp 151.Fn vm_page_test_dirty 152checks if a page has been modified via any of its physical maps, 153and if so, flags the entire page as dirty. 154.Fn vm_page_dirty 155is called to modify the dirty bits. 156.Pp 157.Fn vm_page_dirty 158flags the entire page as dirty. 159It is expected that the page is not currently on the cache queue. 160.Pp 161.Fn vm_page_undirty 162clears all of the dirty bits in a page. 163.Sh NOTES 164None of these functions are allowed to block. 165.Sh AUTHORS 166This manual page was written by 167.An Chad David Aq davidc@acns.ab.ca . 168