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 July 13, 2001 30.Dt VM_PAGE_ALLOC 9 31.Os 32.Sh NAME 33.Nm vm_page_alloc 34.Nd "allocate a page for a vm_object" 35.Sh SYNOPSIS 36.In sys/param.h 37.In vm/vm.h 38.In vm/vm_page.h 39.Ft vm_page_t 40.Fn vm_page_alloc "vm_object_t object" "vm_pindex_t pindex" "int page_req" 41.Sh DESCRIPTION 42The 43.Fn vm_page_alloc 44function allocates a page at 45.Fa pindex 46within 47.Fa object . 48It is assumed that a page has not already been allocated at 49.Fa pindex . 50The page returned is inserted into the object, but is not inserted 51into the pmap. 52.Pp 53.Fn vm_page_alloc 54will not block. 55.Pp 56Its arguments are: 57.Bl -tag -width ".Fa page_req" 58.It Fa object 59The VM object to allocate the page for. 60.It Fa pindex 61The index into the object at which the page should be inserted. 62.It Fa page_req 63A flag indicating how the page should be allocated. 64.Bl -tag -width ".Dv VM_ALLOC_INTERRUPT" 65.It Dv VM_ALLOC_NORMAL 66The page should be allocated with no special treatment. 67.It Dv VM_ALLOC_SYSTEM 68The page can be allocated if the cache queue is empty and the free 69page count is above the interrupt reserved water mark. 70If 71.Dv VM_ALLOC_INTERRUPT 72is set the page can be allocated as long as the free page count is 73greater than zero. 74This flag should be used only when the system really needs the page. 75.It Dv VM_ALLOC_INTERRUPT 76.Fn vm_page_alloc 77is being called during an interrupt and therefore the cache cannot 78be accessed. 79The page will only be returned successfully if the free count is greater 80than zero. 81.It Dv VM_ALLOC_ZERO 82The same as 83.Dv VM_ALLOC_NORMAL 84except the page returned is zeroed. 85.El 86.El 87.Sh RETURN VALUES 88The 89.Vt vm_page_t 90that was allocated is returned if successful; otherwise, 91.Dv NULL 92is returned. 93.Sh NOTES 94The pager process is always upgraded to 95.Dv VM_ALLOC_SYSTEM 96unless 97.Dv VM_ALLOC_INTERRUPT 98is set. 99.Sh AUTHORS 100This man page was written by 101.An Chad David Aq davidc@acns.ab.ca . 102