2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990 The Regents of the University of California.
6 * Copyright (c) 1994 John S. Dyson
9 * This code is derived from software contributed to Berkeley by
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13 * modification, are permitted provided that the following conditions
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36 * from: @(#)vmparam.h 5.9 (Berkeley) 5/12/91
41 #ifndef _MACHINE_VMPARAM_H_
42 #define _MACHINE_VMPARAM_H_ 1
45 * Machine dependent constants for 386.
49 * Virtual memory related constants, all in bytes
51 #define MAXTSIZ (128UL*1024*1024) /* max text size */
53 #define DFLDSIZ (128UL*1024*1024) /* initial data size limit */
56 #define MAXDSIZ (512UL*1024*1024) /* max data size */
59 #define DFLSSIZ (8UL*1024*1024) /* initial stack size limit */
62 #define MAXSSIZ (64UL*1024*1024) /* max stack size */
65 #define SGROWSIZ (128UL*1024) /* amount to grow stack */
69 * Choose between DENSE and SPARSE based on whether lower execution time or
70 * lower kernel address space consumption is desired. Under PAE, kernel
71 * address space is often in short supply.
74 #define VM_PHYSSEG_SPARSE
76 #define VM_PHYSSEG_DENSE
80 * The number of PHYSSEG entries must be one greater than the number
81 * of phys_avail entries because the phys_avail entry that spans the
82 * largest physical address that is accessible by ISA DMA is split
83 * into two PHYSSEG entries.
85 #define VM_PHYSSEG_MAX 17
88 * Create one free page pool. Since the i386 kernel virtual address
89 * space does not include a mapping onto the machine's entire physical
90 * memory, VM_FREEPOOL_DIRECT is defined as an alias for the default
91 * pool, VM_FREEPOOL_DEFAULT.
93 #define VM_NFREEPOOL 1
94 #define VM_FREEPOOL_DEFAULT 0
95 #define VM_FREEPOOL_DIRECT 0
98 * Create two free page lists: VM_FREELIST_DEFAULT is for physical
99 * pages that are above the largest physical address that is
100 * accessible by ISA DMA and VM_FREELIST_LOWMEM is for physical pages
101 * that are below that address.
103 #define VM_NFREELIST 2
104 #define VM_FREELIST_DEFAULT 0
105 #define VM_FREELIST_LOWMEM 1
107 #define VM_LOWMEM_BOUNDARY (16 << 20) /* 16MB ISA DMA limit */
110 * The largest allocation size is 2MB under PAE and 4MB otherwise.
113 #define VM_NFREEORDER 10
115 #define VM_NFREEORDER 11
119 * Enable superpage reservations: 1 level.
121 #ifndef VM_NRESERVLEVEL
122 #define VM_NRESERVLEVEL 1
126 * Level 0 reservations consist of 512 pages when PAE pagetables are
127 * used, and 1024 pages otherwise.
129 #ifndef VM_LEVEL_0_ORDER
130 #if defined(PAE) || defined(PAE_TABLES)
131 #define VM_LEVEL_0_ORDER 9
133 #define VM_LEVEL_0_ORDER 10
138 * Kernel physical load address.
141 #define KERNLOAD (KERNPTDI << PDRSHIFT)
142 #endif /* !defined(KERNLOAD) */
145 * Virtual addresses of things. Derived from the page directory and
146 * page table indexes from pmap.h for precision.
147 * Because of the page that is both a PD and PT, it looks a little
148 * messy at times, but hey, we'll do anything to save a page :-)
151 #define VM_MAX_KERNEL_ADDRESS VADDR(PTDPTDI, 0)
153 #define VM_MIN_KERNEL_ADDRESS 0
155 #define KERNBASE KERNLOAD
157 #define UPT_MAX_ADDRESS VADDR(PTDPTDI, PTDPTDI)
158 #define UPT_MIN_ADDRESS VADDR(PTDPTDI, 0)
160 #define VM_MAXUSER_ADDRESS VADDR(TRPTDI, 0)
162 #define SHAREDPAGE (VM_MAXUSER_ADDRESS - PAGE_SIZE)
163 #define USRSTACK SHAREDPAGE
165 #define VM_MAX_ADDRESS VADDR(PTDPTDI, 0)
166 #define VM_MIN_ADDRESS ((vm_offset_t)0)
168 #define PMAP_TRM_MIN_ADDRESS VM_MAXUSER_ADDRESS
169 #define PMAP_TRM_MAX_ADDRESS 0xffffffff
171 #define PMAP_MAP_LOW VADDR(LOWPTDI, 0)
174 * KVA layout. The unit of the system allocation is single PDE, which
175 * represents NBPDR bytes, aligned to NBPDR. NBPDR is 4M for non-PAE
176 * page tables, and 2M for PAE. Addresses below are shown for non-PAE.
178 * 0x00000000 - 0x003fffff Transient identity map of low memory (0-4M),
179 * normally disabled to catch NULL derefs.
180 * 0x00400000 - 0x007fffff Fixed mapping of the low memory (4-8M).
181 * 0x00800000 - 0xffbfffff KERNBASE (VA) == KERNLOAD (PA), kernel
182 * text + data and all kernel maps. Managed
184 * 0xffc00000 - 0xffdfffff Recursive kernel page table mapping, pointed
185 * to by PTmap. PTD[] recursively points
187 * 0xffe00000 - 0xffffffff Kernel/User mode shared PDE, contains GDT,
188 * IDT, TSS, LDT, trampoline code and stacks.
189 * Managed by pmap_trm_alloc().
193 * How many physical pages per kmem arena virtual page.
195 #ifndef VM_KMEM_SIZE_SCALE
196 #define VM_KMEM_SIZE_SCALE (3)
200 * Optional floor (in bytes) on the size of the kmem arena.
202 #ifndef VM_KMEM_SIZE_MIN
203 #define VM_KMEM_SIZE_MIN (12 * 1024 * 1024)
207 * Optional ceiling (in bytes) on the size of the kmem arena: 40% of the
208 * kernel map rounded to the nearest multiple of the superpage size.
210 #ifndef VM_KMEM_SIZE_MAX
211 #define VM_KMEM_SIZE_MAX (((((VM_MAX_KERNEL_ADDRESS - \
212 VM_MIN_KERNEL_ADDRESS) >> (PDRSHIFT - 2)) + 5) / 10) << PDRSHIFT)
215 /* initial pagein size of beginning of executable file */
216 #ifndef VM_INITIAL_PAGEIN
217 #define VM_INITIAL_PAGEIN 16
220 #define ZERO_REGION_SIZE (64 * 1024) /* 64KB */
222 #ifndef VM_MAX_AUTOTUNE_MAXUSERS
223 #define VM_MAX_AUTOTUNE_MAXUSERS 384
229 #define SFBUF_PROCESS_PAGE
231 #define PMAP_HAS_DMAP 0
232 #define PHYS_TO_DMAP(x) ({ panic("No direct map exists"); 0; })
233 #define DMAP_TO_PHYS(x) ({ panic("No direct map exists"); 0; })
235 #endif /* _MACHINE_VMPARAM_H_ */