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 "allocates a page for the object and index" 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 for 45.Fa pindex 46in the VM object 47.Fa object . 48It is assumed that a page has not already been allocated for 49.Fa pindex 50and 51.Fa object . 52.Pp 53The 54.Fn vm_page_alloc 55function will not block. 56.Pp 57Its arguments are: 58.Bl -tag -width ".Fa page_req" 59.It Fa object 60The VM object to allocate the page for. 61.It Fa pindex 62The index of the page that should be allocated. 63.It Fa page_req 64A flag indicating how the page should be allocated. 65.Bl -tag -width ".Dv VM_ALLOC_INTERRUPT" 66.It Dv VM_ALLOC_NORMAL 67The page should be allocated with no special treatment. 68.It Dv VM_ALLOC_SYSTEM 69The page can be allocated even if the buffer cache queue is empty 70and the free count is above the interrupt reserved water mark. 71This should be used only when the system really needs the page. 72.It Dv VM_ALLOC_INTERRUPT 73.Fn vm_page_alloc 74is being called during an interrupt and therefore the cache cannot 75be accessed. 76The page will only be returned successfully if the free count is greater 77than zero. 78.It Dv VM_ALLOC_ZERO 79The same as 80.Dv VM_ALLOC_NORMAL 81except the page returned is zeroed. 82.El 83.El 84.Sh RETURN VALUES 85A 86.Vt vm_page_t 87is returned if successful; otherwise, 88.Dv NULL 89is returned. 90.Sh NOTES 91The pager process is always upgraded to 92.Dv VM_ALLOC_SYSTEM 93unless 94.Dv VM_ALLOC_INTERRUPT 95is set. 96.Sh AUTHORS 97This man page was written by 98.An Chad David Aq davidc@acns.ab.ca . 99