1/*- 2 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD$"); 29 30/* 31 * Obtain memory configuration information from the BIOS 32 */ 33#include <stand.h> 34#include <machine/pc/bios.h> 35#include "libi386.h" 36#include "btxv86.h" 37 38vm_offset_t memtop, memtop_copyin, high_heap_base; 39uint32_t bios_basemem, bios_extmem, high_heap_size; 40 41static struct bios_smap smap; 42 43/* 44 * The minimum amount of memory to reserve in bios_extmem for the heap. 45 */ 46#define HEAP_MIN (3 * 1024 * 1024) 47 48void 49bios_getmem(void) 50{ 51 uint64_t size; 52 53 /* Parse system memory map */ 54 v86.ebx = 0; 55 do { 56 v86.ctl = V86_FLAGS; 57 v86.addr = 0x15; /* int 0x15 function 0xe820*/ 58 v86.eax = 0xe820; 59 v86.ecx = sizeof(struct bios_smap); 60 v86.edx = SMAP_SIG; 61 v86.es = VTOPSEG(&smap); 62 v86.edi = VTOPOFF(&smap); 63 v86int(); 64 if ((V86_CY(v86.efl)) || (v86.eax != SMAP_SIG)) 65 break; 66 /* look for a low-memory segment that's large enough */ 67 if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base == 0) && 68 (smap.length >= (512 * 1024))) 69 bios_basemem = smap.length; 70 /* look for the first segment in 'extended' memory */ 71 if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base == 0x100000)) { 72 bios_extmem = smap.length; 73 } 74 75 /* 76 * Look for the largest segment in 'extended' memory beyond 77 * 1MB but below 4GB. 78 */ 79 if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base > 0x100000) && 80 (smap.base < 0x100000000ull)) { 81 size = smap.length; 82 83 /* 84 * If this segment crosses the 4GB boundary, truncate it. 85 */ 86 if (smap.base + size > 0x100000000ull) 87 size = 0x100000000ull - smap.base; 88 89 if (size > high_heap_size) { 90 high_heap_size = size; 91 high_heap_base = smap.base; 92 } 93 } 94 } while (v86.ebx != 0); 95 96 /* Fall back to the old compatibility function for base memory */ 97 if (bios_basemem == 0) { 98 v86.ctl = 0; 99 v86.addr = 0x12; /* int 0x12 */ 100 v86int(); 101 102 bios_basemem = (v86.eax & 0xffff) * 1024; 103 } 104 105 /* Fall back through several compatibility functions for extended memory */ 106 if (bios_extmem == 0) { 107 v86.ctl = V86_FLAGS; 108 v86.addr = 0x15; /* int 0x15 function 0xe801*/ 109 v86.eax = 0xe801; 110 v86int(); 111 if (!(V86_CY(v86.efl))) { 112 bios_extmem = ((v86.ecx & 0xffff) + ((v86.edx & 0xffff) * 64)) * 1024; 113 } 114 } 115 if (bios_extmem == 0) { 116 v86.ctl = 0; 117 v86.addr = 0x15; /* int 0x15 function 0x88*/ 118 v86.eax = 0x8800; 119 v86int(); 120 bios_extmem = (v86.eax & 0xffff) * 1024; 121 } 122 123 /* Set memtop to actual top of memory */ 124 memtop = memtop_copyin = 0x100000 + bios_extmem; 125 126 /* 127 * If we have extended memory and did not find a suitable heap 128 * region in the SMAP, use the last 3MB of 'extended' memory as a 129 * high heap candidate. 130 */ 131 if (bios_extmem >= HEAP_MIN && high_heap_size < HEAP_MIN) { 132 high_heap_size = HEAP_MIN; 133 high_heap_base = memtop - HEAP_MIN; 134 } 135} 136