2 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
26 * $FreeBSD: src/sys/boot/i386/libi386/biosmem.c,v 1.7 2003/08/25 23:28:31 obrien Exp $
29 * Obtain memory configuration information from the BIOS
32 #include <machine/pc/bios.h>
33 #include <machine/psl.h>
37 #define LOADER_HEAP_SIZE (1024 * 1024)
41 u_int32_t bios_basemem, bios_extmem, bios_howmem;
43 static struct bios_smap smap;
50 /* Parse system memory map */
53 #ifdef COMCONSOLE_DEBUG
54 printf("GET SMAP %d: ", v86.ebx);
57 v86.addr = 0x15; /* int 0x15 function 0xe820*/
59 v86.ecx = sizeof(struct bios_smap);
61 v86.es = VTOPSEG(&smap);
62 v86.edi = VTOPOFF(&smap);
64 #ifdef COMCONSOLE_DEBUG
65 printf("RESULT: EFL=%04x EAX=%08x SMAPTYPE %d BASE %08x%08x LEN %08x%08x\n",
66 v86.efl, v86.eax, smap.type,
67 (int)(smap.base >> 32), (int)smap.base,
68 (int)(smap.length >> 32), (int)smap.length);
70 if ((v86.efl & PSL_C) || (v86.eax != SMAP_SIG))
72 /* look for a low-memory segment that's large enough */
73 if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base == 0) &&
74 (smap.length >= (512 * 1024))) {
75 bios_basemem = smap.length;
78 /* look for the first segment in 'extended' memory */
79 if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base == 0x100000)) {
80 bios_extmem = smap.length;
82 } while (v86.ebx != 0);
84 /* Fall back to the old compatibility function for base memory */
85 if (bios_basemem == 0) {
87 v86.addr = 0x12; /* int 0x12 */
90 bios_basemem = (v86.eax & 0xffff) * 1024;
94 /* Fall back through several compatibility functions for extended memory */
95 if (bios_extmem == 0) {
97 v86.addr = 0x15; /* int 0x15 function 0xe801*/
100 if (!(v86.efl & PSL_C)) {
101 v = ((v86.ecx & 0xffff) +
102 ((int64_t)(v86.edx & 0xffff) * 64)) * 1024;
108 if (bios_extmem == 0) {
110 v86.addr = 0x15; /* int 0x15 function 0x88*/
113 bios_extmem = (v86.eax & 0xffff) * 1024;
117 * Set memtop to actual top of memory
119 * This is broken because the boot loader generally needs more than 16MB
120 * now but the extmem usually calculates to ~14-16MB (which is the fully
121 * segmented limit). Disk I/O will use bounce buffers.
125 #if 0 /* XXX ignored */
126 memtop = 0x100000 + bios_extmem;
128 memtop = 64 * 1024 * 1024;
129 heapbase = memtop - LOADER_HEAP_SIZE;