beb3c3a9c5
but I see no benefit from it today. VM_PROT_READ_IS_EXEC was only intended for use on processors that do not distinguish between read and execute permission. On an mmap(2) or mprotect(2), it automatically added execute permission if the caller specified permissions included read permission. The hope was that this would reduce the number of vm map entries needed to implement an address space because there would be fewer neighboring vm map entries that differed only in the presence or absence of VM_PROT_EXECUTE. (See vm/vm_mmap.c revision 1.56.) Today, I don't see any real applications that benefit from VM_PROT_READ_IS_EXEC. In any case, vm map entries are now organized as a self-adjusting binary search tree instead of an ordered list. So, the need for coalescing vm map entries is not as great as it once was.
206 lines
5.9 KiB
C
206 lines
5.9 KiB
C
/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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* Copyright (c) 1994 John S. Dyson
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* William Jolitz.
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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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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)vmparam.h 5.9 (Berkeley) 5/12/91
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* $FreeBSD$
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*/
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#ifndef _MACHINE_VMPARAM_H_
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#define _MACHINE_VMPARAM_H_ 1
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/*
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* Machine dependent constants for 386.
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*/
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/*
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* Virtual memory related constants, all in bytes
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*/
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#define MAXTSIZ (128UL*1024*1024) /* max text size */
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#ifndef DFLDSIZ
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#define DFLDSIZ (128UL*1024*1024) /* initial data size limit */
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#endif
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#ifndef MAXDSIZ
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#define MAXDSIZ (512UL*1024*1024) /* max data size */
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#endif
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#ifndef DFLSSIZ
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#define DFLSSIZ (8UL*1024*1024) /* initial stack size limit */
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#endif
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#ifndef MAXSSIZ
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#define MAXSSIZ (64UL*1024*1024) /* max stack size */
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#endif
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#ifndef SGROWSIZ
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#define SGROWSIZ (128UL*1024) /* amount to grow stack */
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#endif
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/*
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* The time for a process to be blocked before being very swappable.
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* This is a number of seconds which the system takes as being a non-trivial
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* amount of real time. You probably shouldn't change this;
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* it is used in subtle ways (fractions and multiples of it are, that is, like
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* half of a ``long time'', almost a long time, etc.)
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* It is related to human patience and other factors which don't really
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* change over time.
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*/
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#define MAXSLP 20
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/*
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* The physical address space is densely populated.
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*/
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#define VM_PHYSSEG_DENSE
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/*
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* The number of PHYSSEG entries must be one greater than the number
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* of phys_avail entries because the phys_avail entry that spans the
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* largest physical address that is accessible by ISA DMA is split
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* into two PHYSSEG entries.
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*/
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#define VM_PHYSSEG_MAX 17
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/*
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* Create two free page pools. Since the i386 kernel virtual address
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* space does not include a mapping onto the machine's entire physical
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* memory, VM_FREEPOOL_DIRECT is defined as an alias for the default
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* pool, VM_FREEPOOL_DEFAULT.
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*/
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#define VM_NFREEPOOL 2
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#define VM_FREEPOOL_CACHE 1
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#define VM_FREEPOOL_DEFAULT 0
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#define VM_FREEPOOL_DIRECT 0
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/*
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* Create two free page lists: VM_FREELIST_DEFAULT is for physical
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* pages that are above the largest physical address that is
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* accessible by ISA DMA and VM_FREELIST_ISADMA is for physical pages
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* that are below that address.
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*/
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#define VM_NFREELIST 2
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#define VM_FREELIST_DEFAULT 0
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#define VM_FREELIST_ISADMA 1
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/*
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* The largest allocation size is 2MB under PAE and 4MB otherwise.
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*/
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#ifdef PAE
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#define VM_NFREEORDER 10
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#else
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#define VM_NFREEORDER 11
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#endif
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/*
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* Enable superpage reservations: 1 level.
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*/
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#ifndef VM_NRESERVLEVEL
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#define VM_NRESERVLEVEL 1
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#endif
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/*
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* Level 0 reservations consist of 512 pages under PAE and 1024 pages
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* otherwise.
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*/
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#ifndef VM_LEVEL_0_ORDER
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#ifdef PAE
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#define VM_LEVEL_0_ORDER 9
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#else
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#define VM_LEVEL_0_ORDER 10
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#endif
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#endif
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/*
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* Kernel physical load address.
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*/
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#ifndef KERNLOAD
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#if defined(XEN) && !defined(XEN_PRIVILEGED_GUEST)
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#define KERNLOAD 0
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#else
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#define KERNLOAD (1 << PDRSHIFT)
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#endif
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#endif /* !defined(KERNLOAD) */
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/*
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* Virtual addresses of things. Derived from the page directory and
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* page table indexes from pmap.h for precision.
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* Because of the page that is both a PD and PT, it looks a little
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* messy at times, but hey, we'll do anything to save a page :-)
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*/
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#ifdef XEN
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#define VM_MAX_KERNEL_ADDRESS HYPERVISOR_VIRT_START
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#else
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#define VM_MAX_KERNEL_ADDRESS VADDR(KPTDI+NKPDE-1, NPTEPG-1)
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#endif
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#define VM_MIN_KERNEL_ADDRESS VADDR(PTDPTDI, PTDPTDI)
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#define KERNBASE VADDR(KPTDI, 0)
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#define UPT_MAX_ADDRESS VADDR(PTDPTDI, PTDPTDI)
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#define UPT_MIN_ADDRESS VADDR(PTDPTDI, 0)
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#define VM_MAXUSER_ADDRESS VADDR(PTDPTDI, 0)
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#define USRSTACK VM_MAXUSER_ADDRESS
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#define VM_MAX_ADDRESS VADDR(PTDPTDI, PTDPTDI)
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#define VM_MIN_ADDRESS ((vm_offset_t)0)
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/* virtual sizes (bytes) for various kernel submaps */
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#ifndef VM_KMEM_SIZE
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#define VM_KMEM_SIZE (12 * 1024 * 1024)
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#endif
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/*
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* How many physical pages per KVA page allocated.
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* min(max(max(VM_KMEM_SIZE, Physical memory/VM_KMEM_SIZE_SCALE),
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* VM_KMEM_SIZE_MIN), VM_KMEM_SIZE_MAX)
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* is the total KVA space allocated for kmem_map.
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*/
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#ifndef VM_KMEM_SIZE_SCALE
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#define VM_KMEM_SIZE_SCALE (3)
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#endif
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/*
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* Ceiling on amount of kmem_map kva space.
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*/
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#ifndef VM_KMEM_SIZE_MAX
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#define VM_KMEM_SIZE_MAX (320 * 1024 * 1024)
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#endif
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/* initial pagein size of beginning of executable file */
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#ifndef VM_INITIAL_PAGEIN
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#define VM_INITIAL_PAGEIN 16
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#endif
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#endif /* _MACHINE_VMPARAM_H_ */
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