biosmem.c revision 55342 
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 55342 2000-01-03 15:43:52Z nyan $
27 */
28
29/*
30 * Obtain memory configuration information from the BIOS
31 */
32#include <stand.h>
33#include "btxv86.h"
34
35vm_offset_t	memtop;
36u_int32_t	bios_basemem, bios_extmem;
37
38#ifndef PC98
39#define SMAPSIG	0x534D4150
40
41struct smap {
42    u_int64_t	base;
43    u_int64_t	length;
44    u_int32_t	type;
45} __attribute__ ((packed));
46
47static struct smap smap;
48#endif
49
50void
51bios_getmem(void)
52{
53
54#ifdef PC98
55    bios_basemem = ((*(u_char *)PTOV(0xA1501) & 0x07) + 1) * 128 * 1024;
56    bios_extmem = *(u_char *)PTOV(0xA1401) * 128 * 1024 +
57	*(u_int16_t *)PTOV(0xA1594) * 1024 * 1024;
58#else
59    /* Parse system memory map */
60    v86.ebx = 0;
61    do {
62	v86.ctl = V86_FLAGS;
63	v86.addr = 0x15;		/* int 0x15 function 0xe820*/
64	v86.eax = 0xe820;
65	v86.ecx = sizeof(struct smap);
66	v86.edx = SMAPSIG;
67	v86.es = VTOPSEG(&smap);
68	v86.edi = VTOPOFF(&smap);
69	v86int();
70	if ((v86.efl & 1) || (v86.eax != SMAPSIG))
71	    break;
72	/* look for a low-memory segment that's large enough */
73	if ((smap.type == 1) && (smap.base == 0) && (smap.length >= (512 * 1024)))
74	    bios_basemem = smap.length;
75	/* look for the first segment in 'extended' memory */
76	if ((smap.type == 1) && (smap.base == 0x100000)) {
77	    bios_extmem = smap.length;
78	}
79    } while (v86.ebx != 0);
80
81    /* Fall back to the old compatibility function for base memory */
82    if (bios_basemem == 0) {
83	v86.ctl = 0;
84	v86.addr = 0x12;		/* int 0x12 */
85	v86int();
86
87	bios_basemem = (v86.eax & 0xffff) * 1024;
88    }
89
90    /* Fall back through several compatibility functions for extended memory */
91    if (bios_extmem == 0) {
92	v86.ctl = V86_FLAGS;
93	v86.addr = 0x15;		/* int 0x15 function 0xe801*/
94	v86.eax = 0xe801;
95	v86int();
96	if (!(v86.efl & 1)) {
97	    bios_extmem = ((v86.ecx & 0xffff) + ((v86.edx & 0xffff) * 64)) * 1024;
98	}
99    }
100    if (bios_extmem == 0) {
101	v86.ctl = 0;
102	v86.addr = 0x15;		/* int 0x15 function 0x88*/
103	v86.eax = 0x8800;
104	v86int();
105	bios_extmem = (v86.eax & 0xffff) * 1024;
106    }
107#endif
108
109    /* Set memtop to actual top of memory */
110    memtop = 0x100000 + bios_extmem;
111
112}
113
114