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: src/share/man/man9/vm_page_alloc.9,v 1.6 2005/06/28 20:15:18 hmp Exp $ 28.\" 29.Dd December 19, 2010 30.Dt VM_PAGE_ALLOC 9 31.Os 32.Sh NAME 33.Nm vm_page_alloc 34.Nd "allocate a page for a" 35.Vt vm_object 36.Sh SYNOPSIS 37.In sys/param.h 38.In vm/vm.h 39.In vm/vm_page.h 40.Ft vm_page_t 41.Fn vm_page_alloc "vm_object_t object" "vm_pindex_t pindex" "int page_req" 42.Sh DESCRIPTION 43The 44.Fn vm_page_alloc 45function allocates a page at 46.Fa pindex 47within 48.Fa object . 49It is assumed that a page has not already been allocated at 50.Fa pindex . 51The page returned is inserted into the object, but is not inserted 52into the pmap. The vm_object must be locked on entry. 53.Pp 54.Fn vm_page_alloc 55will 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 into the object at which the page should be inserted. 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_QUICK 69The page should only be allocated from the free queue. 70.It Dv VM_ALLOC_SYSTEM 71The page can be allocated if the cache queue is empty and the free 72page count is above the interrupt reserved water mark. 73If 74.Dv VM_ALLOC_INTERRUPT 75is set, the page can be allocated as long as the free page count is 76greater than zero. 77This flag should be used only when the system really needs the page. 78.It Dv VM_ALLOC_INTERRUPT 79.Fn vm_page_alloc 80is being called during an interrupt and therefore the cache cannot 81be accessed. 82The page will only be returned successfully if the free count is greater 83than zero. 84.It Dv VM_ALLOC_ZERO 85Indicate a preference for a pre-zeroed page. 86There is no guarantee that the page thus returned will be zeroed, but 87it will be marked as such. 88.El 89.El 90.Sh RETURN VALUES 91The 92.Vt vm_page_t 93that was allocated is returned if successful; otherwise, 94.Dv NULL 95is returned. The returned page will be marked PG_BUSY. 96.Sh AUTHORS 97This manual page was written by 98.An Chad David Aq Mt davidc@acns.ab.ca . 99