FreeBSD/Linux Kernel Cross Reference
sys/i386/include/vmparam.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1990 The Regents of the University of California.
      * All rights reserved.
      * Copyright (c) 1994 John S. Dyson
      * All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
     * William Jolitz.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      from: @(#)vmparam.h     5.9 (Berkeley) 5/12/91
     * $FreeBSD$
     */
    
    #ifndef _MACHINE_VMPARAM_H_
    #define _MACHINE_VMPARAM_H_ 1
    
    /*
     * Machine dependent constants for 386.
     */
    
    /*
     * Virtual memory related constants, all in bytes
     */
    #define MAXTSIZ         (128UL*1024*1024)       /* max text size */
    #ifndef DFLDSIZ
    #define DFLDSIZ         (128UL*1024*1024)       /* initial data size limit */
    #endif
    #ifndef MAXDSIZ
    #define MAXDSIZ         (512UL*1024*1024)       /* max data size */
    #endif
    #ifndef DFLSSIZ
    #define DFLSSIZ         (8UL*1024*1024)         /* initial stack size limit */
    #endif
    #ifndef MAXSSIZ
    #define MAXSSIZ         (64UL*1024*1024)        /* max stack size */
    #endif
    #ifndef SGROWSIZ
    #define SGROWSIZ        (128UL*1024)            /* amount to grow stack */
    #endif
    
    /*
     * Choose between DENSE and SPARSE based on whether lower execution time or
     * lower kernel address space consumption is desired.  Under PAE, kernel
     * address space is often in short supply.
     */
    #ifdef PAE
    #define VM_PHYSSEG_SPARSE
    #else
    #define VM_PHYSSEG_DENSE
    #endif
    
    /*
     * The number of PHYSSEG entries must be one greater than the number
     * of phys_avail entries because the phys_avail entry that spans the
     * largest physical address that is accessible by ISA DMA is split
     * into two PHYSSEG entries. 
     */
    #define VM_PHYSSEG_MAX          17
    
    /*
     * Create one free page pool.  Since the i386 kernel virtual address
     * space does not include a mapping onto the machine's entire physical
     * memory, VM_FREEPOOL_DIRECT is defined as an alias for the default
     * pool, VM_FREEPOOL_DEFAULT.
     */
    #define VM_NFREEPOOL            1
    #define VM_FREEPOOL_DEFAULT     0
    #define VM_FREEPOOL_DIRECT      0
    
    /*
     * Create up to three free page lists: VM_FREELIST_DMA32 is for physical pages
     * that have physical addresses below 4G but are not accessible by ISA DMA,
     * and VM_FREELIST_ISADMA is for physical pages that are accessible by ISA
    * DMA.
    */
   #define VM_NFREELIST            3
   #define VM_FREELIST_DEFAULT     0
   #define VM_FREELIST_DMA32       1
   #define VM_FREELIST_LOWMEM      2
   
   #define VM_LOWMEM_BOUNDARY      (16 << 20)      /* 16MB ISA DMA limit */
   
   /*
    * Always create DMA32 freelist if there is any memory above 4G.
    * Bounce dma is extremely fragile and simultaneously intensively
    * used.
    */
   #define VM_DMA32_NPAGES_THRESHOLD       1
   
   /*
    * The largest allocation size is 2MB under PAE and 4MB otherwise.
    */
   #define VM_NFREEORDER_PAE               10
   #define VM_NFREEORDER_NOPAE             11
   #define VM_NFREEORDER_MAX               VM_NFREEORDER_NOPAE
   #define VM_NFREEORDER                   i386_pmap_VM_NFREEORDER
   
   /*
    * Enable superpage reservations: 1 level.
    */
   #ifndef VM_NRESERVLEVEL
   #define VM_NRESERVLEVEL         1
   #endif
   
   /*
    * Level 0 reservations consist of 512 pages when PAE pagetables are
    * used, and 1024 pages otherwise.
    */
   #ifndef VM_LEVEL_0_ORDER
   #define VM_LEVEL_0_ORDER_PAE    9
   #define VM_LEVEL_0_ORDER_NOPAE  10
   #define VM_LEVEL_0_ORDER_MAX    VM_LEVEL_0_ORDER_NOPAE
   #define VM_LEVEL_0_ORDER        i386_pmap_VM_LEVEL_0_ORDER
   #else
   #define VM_LEVEL_0_ORDER_MAX    VM_LEVEL_0_ORDER
   #endif
   
   /*
    * Kernel physical load address.
    */
   #ifndef KERNLOAD
   #define KERNLOAD                (8 * 1024 * 1024)
   #endif /* !defined(KERNLOAD) */
   
   /*
    * Virtual addresses of things.  Derived from the page directory and
    * page table indexes from pmap.h for precision.
    * Because of the page that is both a PD and PT, it looks a little
    * messy at times, but hey, we'll do anything to save a page :-)
    */
   
   #define VM_MAX_KERNEL_ADDRESS   (0xffffffffU - 16 * 1024 * 1024 + 1)
   
   #define VM_MIN_KERNEL_ADDRESS   0
   
   #define KERNBASE                KERNLOAD
   
   #define UPT_MAX_ADDRESS         VADDR(PTDPTDI, PTDPTDI)
   #define UPT_MIN_ADDRESS         VADDR(PTDPTDI, 0)
   
   #define VM_MAXUSER_ADDRESS      (0xffffffff - 4 * 1024 * 1024 + 1)
   
   #define SHAREDPAGE              (VM_MAXUSER_ADDRESS - PAGE_SIZE)
   #define USRSTACK                SHAREDPAGE
   
   #define VM_MAX_ADDRESS          VADDR(PTDPTDI, 0)
   #define VM_MIN_ADDRESS          ((vm_offset_t)0)
   
   #define PMAP_TRM_MIN_ADDRESS    VM_MAXUSER_ADDRESS
   #define PMAP_TRM_MAX_ADDRESS    0xffffffff
   
   #define PMAP_MAP_LOW            (4 * 1024 * 1024)
   
   /*
    * KVA layout.  The unit of the system allocation is single PDE, which
    * represents NBPDR bytes, aligned to NBPDR.  NBPDR is 4M for non-PAE
    * page tables, and 2M for PAE, so PAE mode requires twice as many PTDs
    * to create the same memory map as non-PAE.
    *
    * 0x00000000 - 0x003fffff      Transient identity map of low memory (0-4M),
    *                              normally disabled to catch NULL derefs.
    * 0x00400000 - 0x007fffff      Fixed mapping of the low memory (4-8M).
    * 0x00800000 - 0xffbfffff      KERNBASE (VA) == KERNLOAD (PA), kernel
    *                              text + data and all kernel maps.  Managed
    *                              by MI VM.
    * 0xffc00000 - 0xffdfffff      Recursive kernel page table mapping, pointed
    *                              to by PTmap.  PTD[] recursively points
    *                              into PTmap.
    * 0xffe00000 - 0xffffffff      Kernel/User mode shared PDE, contains GDT,
    *                              IDT, TSS, LDT, trampoline code and stacks.
    *                              Managed by pmap_trm_alloc().
    */
   
   /*
    * How many physical pages per kmem arena virtual page.
    */
   #ifndef VM_KMEM_SIZE_SCALE
   #define VM_KMEM_SIZE_SCALE      (1)
   #endif
   
   /*
    * Optional floor (in bytes) on the size of the kmem arena.
    */
   #ifndef VM_KMEM_SIZE_MIN
   #define VM_KMEM_SIZE_MIN        (12 * 1024 * 1024)
   #endif
   
   /*
    * Optional ceiling (in bytes) on the size of the kmem arena: 40% of the
    * kernel map rounded to the nearest multiple of the superpage size.
    */
   #ifndef VM_KMEM_SIZE_MAX
   #define VM_KMEM_SIZE_MAX        (((((VM_MAX_KERNEL_ADDRESS - \
       VM_MIN_KERNEL_ADDRESS) >> (PDRSHIFT - 2)) + 5) / 10) << PDRSHIFT)
   #endif
   
   /* initial pagein size of beginning of executable file */
   #ifndef VM_INITIAL_PAGEIN
   #define VM_INITIAL_PAGEIN       16
   #endif
   
   #define ZERO_REGION_SIZE        (64 * 1024)     /* 64KB */
   
   #ifndef VM_MAX_AUTOTUNE_MAXUSERS
   #define VM_MAX_AUTOTUNE_MAXUSERS 384
   #endif
   
   #define SFBUF
   #define SFBUF_MAP
   #define SFBUF_CPUSET
   #define SFBUF_PROCESS_PAGE
   
   #define PMAP_HAS_DMAP   0
   #define PHYS_TO_DMAP(x) ({ panic("No direct map exists"); 0; })
   #define DMAP_TO_PHYS(x) ({ panic("No direct map exists"); 0; })
   
   /*
    * No non-transparent large page support in the pmap.
    */
   #define PMAP_HAS_LARGEPAGES     0
   
   /*
    * Need a page dump array for minidump.
    */
   #define MINIDUMP_PAGE_TRACKING  1
   
   #endif /* _MACHINE_VMPARAM_H_ */

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