biosmem.c revision 103870 
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 * $FreeBSD: head/sys/boot/pc98/libpc98/biosmem.c 103870 2002-09-23 18:54:32Z alfred $
27 */
28
29/*
30 * Obtain memory configuration information from the BIOS
31 */
32#include <stand.h>
33#include "libi386.h"
34#include "btxv86.h"
35
36vm_offset_t	memtop;
37u_int32_t	bios_basemem, bios_extmem;
38
39#ifndef PC98
40#define SMAPSIG	0x534D4150
41
42struct smap {
43    u_int64_t	base;
44    u_int64_t	length;
45    u_int32_t	type;
46} __packed;
47
48static struct smap smap;
49#endif
50
51void
52bios_getmem(void)
53{
54
55#ifdef PC98
56    bios_basemem = ((*(u_char *)PTOV(0xA1501) & 0x07) + 1) * 128 * 1024;
57    bios_extmem = *(u_char *)PTOV(0xA1401) * 128 * 1024 +
58	*(u_int16_t *)PTOV(0xA1594) * 1024 * 1024;
59#else
60    /* Parse system memory map */
61    v86.ebx = 0;
62    do {
63	v86.ctl = V86_FLAGS;
64	v86.addr = 0x15;		/* int 0x15 function 0xe820*/
65	v86.eax = 0xe820;
66	v86.ecx = sizeof(struct smap);
67	v86.edx = SMAPSIG;
68	v86.es = VTOPSEG(&smap);
69	v86.edi = VTOPOFF(&smap);
70	v86int();
71	if ((v86.efl & 1) || (v86.eax != SMAPSIG))
72	    break;
73	/* look for a low-memory segment that's large enough */
74	if ((smap.type == 1) && (smap.base == 0) && (smap.length >= (512 * 1024)))
75	    bios_basemem = smap.length;
76	/* look for the first segment in 'extended' memory */
77	if ((smap.type == 1) && (smap.base == 0x100000)) {
78	    bios_extmem = smap.length;
79	}
80    } while (v86.ebx != 0);
81
82    /* Fall back to the old compatibility function for base memory */
83    if (bios_basemem == 0) {
84	v86.ctl = 0;
85	v86.addr = 0x12;		/* int 0x12 */
86	v86int();
87
88	bios_basemem = (v86.eax & 0xffff) * 1024;
89    }
90
91    /* Fall back through several compatibility functions for extended memory */
92    if (bios_extmem == 0) {
93	v86.ctl = V86_FLAGS;
94	v86.addr = 0x15;		/* int 0x15 function 0xe801*/
95	v86.eax = 0xe801;
96	v86int();
97	if (!(v86.efl & 1)) {
98	    bios_extmem = ((v86.ecx & 0xffff) + ((v86.edx & 0xffff) * 64)) * 1024;
99	}
100    }
101    if (bios_extmem == 0) {
102	v86.ctl = 0;
103	v86.addr = 0x15;		/* int 0x15 function 0x88*/
104	v86.eax = 0x8800;
105	v86int();
106	bios_extmem = (v86.eax & 0xffff) * 1024;
107    }
108#endif
109
110    /* Set memtop to actual top of memory */
111    memtop = 0x100000 + bios_extmem;
112
113}
114
115