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 "libi386.h"
35#include "btxv86.h"
36
37vm_offset_t	memtop, memtop_copyin, high_heap_base;
38uint32_t	bios_basemem, bios_extmem, high_heap_size;
39
40/*
41 * The minimum amount of memory to reserve in bios_extmem for the heap.
42 */
43#define	HEAP_MIN	(3 * 1024 * 1024)
44
45void
46bios_getmem(void)
47{
48
49    bios_basemem = ((*(u_char *)PTOV(0xA1501) & 0x07) + 1) * 128 * 1024;
50    bios_extmem = *(u_char *)PTOV(0xA1401) * 128 * 1024 +
51	*(u_int16_t *)PTOV(0xA1594) * 1024 * 1024;
52
53    /* Set memtop to actual top of memory */
54    memtop = memtop_copyin = 0x100000 + bios_extmem;
55
56    /*
57     * If we have extended memory, use the last 3MB of 'extended' memory
58     * as a high heap candidate.
59     */
60    if (bios_extmem >= HEAP_MIN) {
61	high_heap_size = HEAP_MIN;
62	high_heap_base = memtop - HEAP_MIN;
63    }
64}
65