biosmem.c revision 119880 
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: head/sys/boot/pc98/libpc98/biosmem.c 119880 2003-09-08 09:11:32Z obrien $");
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;
38u_int32_t	bios_basemem, bios_extmem;
39
40#ifndef PC98
41#define SMAPSIG	0x534D4150
42
43struct smap {
44    u_int64_t	base;
45    u_int64_t	length;
46    u_int32_t	type;
47} __packed;
48
49static struct smap smap;
50#endif
51
52void
53bios_getmem(void)
54{
55
56#ifdef PC98
57    bios_basemem = ((*(u_char *)PTOV(0xA1501) & 0x07) + 1) * 128 * 1024;
58    bios_extmem = *(u_char *)PTOV(0xA1401) * 128 * 1024 +
59	*(u_int16_t *)PTOV(0xA1594) * 1024 * 1024;
60#else
61    /* Parse system memory map */
62    v86.ebx = 0;
63    do {
64	v86.ctl = V86_FLAGS;
65	v86.addr = 0x15;		/* int 0x15 function 0xe820*/
66	v86.eax = 0xe820;
67	v86.ecx = sizeof(struct smap);
68	v86.edx = SMAPSIG;
69	v86.es = VTOPSEG(&smap);
70	v86.edi = VTOPOFF(&smap);
71	v86int();
72	if ((v86.efl & 1) || (v86.eax != SMAPSIG))
73	    break;
74	/* look for a low-memory segment that's large enough */
75	if ((smap.type == 1) && (smap.base == 0) && (smap.length >= (512 * 1024)))
76	    bios_basemem = smap.length;
77	/* look for the first segment in 'extended' memory */
78	if ((smap.type == 1) && (smap.base == 0x100000)) {
79	    bios_extmem = smap.length;
80	}
81    } while (v86.ebx != 0);
82
83    /* Fall back to the old compatibility function for base memory */
84    if (bios_basemem == 0) {
85	v86.ctl = 0;
86	v86.addr = 0x12;		/* int 0x12 */
87	v86int();
88
89	bios_basemem = (v86.eax & 0xffff) * 1024;
90    }
91
92    /* Fall back through several compatibility functions for extended memory */
93    if (bios_extmem == 0) {
94	v86.ctl = V86_FLAGS;
95	v86.addr = 0x15;		/* int 0x15 function 0xe801*/
96	v86.eax = 0xe801;
97	v86int();
98	if (!(v86.efl & 1)) {
99	    bios_extmem = ((v86.ecx & 0xffff) + ((v86.edx & 0xffff) * 64)) * 1024;
100	}
101    }
102    if (bios_extmem == 0) {
103	v86.ctl = 0;
104	v86.addr = 0x15;		/* int 0x15 function 0x88*/
105	v86.eax = 0x8800;
106	v86int();
107	bios_extmem = (v86.eax & 0xffff) * 1024;
108    }
109#endif
110
111    /* Set memtop to actual top of memory */
112    memtop = 0x100000 + bios_extmem;
113
114}
115
116