112 lines
3.8 KiB
C
112 lines
3.8 KiB
C
/* $NetBSD: uvm_anon.h,v 1.13 2000/12/27 09:17:04 chs Exp $ */
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/*
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*
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* Copyright (c) 1997 Charles D. Cranor and Washington University.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Charles D. Cranor and
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* Washington University.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _UVM_UVM_ANON_H_
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#define _UVM_UVM_ANON_H_
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/*
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* uvm_anon.h
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*/
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/*
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* anonymous memory management
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*
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* anonymous virtual memory is short term virtual memory that goes away
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* when the processes referencing it go away. an anonymous page of
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* virtual memory is described by the following data structure:
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*/
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struct vm_anon {
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int an_ref; /* reference count [an_lock] */
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simple_lock_data_t an_lock; /* lock for an_ref */
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union {
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struct vm_anon *an_nxt; /* if on free list [afreelock] */
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struct vm_page *an_page;/* if in RAM [an_lock] */
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} u;
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int an_swslot; /* drum swap slot # (if != 0)
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[an_lock. also, it is ok to read
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an_swslot if we hold an_page PG_BUSY] */
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};
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/*
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* a pool of vm_anon data structures is allocated and put on a global
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* free list at boot time. vm_anon's on the free list use "an_nxt" as
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* a pointer to the next item on the free list. for active vm_anon's
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* the data can be in one of the following state: [1] in a vm_page
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* with no backing store allocated yet, [2] in a vm_page with backing
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* store allocated, or [3] paged out to backing store (no vm_page).
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*
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* for pageout in case [2]: if the page has been modified then we must
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* flush it out to backing store, otherwise we can just dump the
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* vm_page.
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*/
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/*
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* anons are grouped together in anonymous memory maps, or amaps.
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* amaps are defined in uvm_amap.h.
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*/
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/*
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* processes reference anonymous virtual memory maps with an anonymous
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* reference structure:
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*/
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struct vm_aref {
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int ar_pageoff; /* page offset into amap we start */
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struct vm_amap *ar_amap; /* pointer to amap */
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};
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/*
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* the offset field indicates which part of the amap we are referencing.
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* locked by vm_map lock.
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*/
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#ifdef _KERNEL
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/*
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* prototypes
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*/
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struct vm_anon *uvm_analloc __P((void));
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void uvm_anfree __P((struct vm_anon *));
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void uvm_anon_init __P((void));
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int uvm_anon_add __P((int));
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void uvm_anon_remove __P((int));
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struct vm_page *uvm_anon_lockloanpg __P((struct vm_anon *));
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void uvm_anon_dropswap __P((struct vm_anon *));
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boolean_t anon_swap_off __P((int, int));
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#endif /* _KERNEL */
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#endif /* _UVM_UVM_ANON_H_ */
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