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" 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. 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_SYSTEM 69The page can be allocated if the cache queue is empty and the free 70page count is above the interrupt reserved water mark. 71If 72.Dv VM_ALLOC_INTERRUPT 73is set, the page can be allocated as long as the free page count is 74greater than zero. 75This flag should be used only when the system really needs the page. 76.It Dv VM_ALLOC_INTERRUPT 77.Fn vm_page_alloc 78is being called during an interrupt and therefore the cache cannot 79be accessed. 80The page will only be returned successfully if the free count is greater 81than zero. 82.It Dv VM_ALLOC_ZERO 83Indicate a preference for a pre-zeroed page. 84There is no guarantee that the page thus returned will be zeroed, but 85it will be marked as such. 86.It Dv VM_ALLOC_NOOBJ 87The page is associated with an unmanaged memory region, that is, there 88is no backing VM object. 89This is typically used to allocate pages within the kernel virtual 90address space. 91.El 92.El 93.Sh RETURN VALUES 94The 95.Vt vm_page_t 96that was allocated is returned if successful; otherwise, 97.Dv NULL 98is returned. 99.Sh NOTES 100The pager process is always upgraded to 101.Dv VM_ALLOC_SYSTEM 102unless 103.Dv VM_ALLOC_INTERRUPT 104is set. 105.Sh AUTHORS 106This manual page was written by 107.An Chad David Aq davidc@acns.ab.ca . 108