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 <machine/pc/bios.h>
35#include "libi386.h"
36#include "btxv86.h"
37
38vm_offset_t	memtop, memtop_copyin, high_heap_base;
39uint32_t	bios_basemem, bios_extmem, high_heap_size;
40
41static struct bios_smap smap;
42
43/*
44 * The minimum amount of memory to reserve in bios_extmem for the heap.
45 */
46#define	HEAP_MIN	(3 * 1024 * 1024)
47
48void
49bios_getmem(void)
50{
51    uint64_t size;
52
53    /* Parse system memory map */
54    v86.ebx = 0;
55    do {
56	v86.ctl = V86_FLAGS;
57	v86.addr = 0x15;		/* int 0x15 function 0xe820*/
58	v86.eax = 0xe820;
59	v86.ecx = sizeof(struct bios_smap);
60	v86.edx = SMAP_SIG;
61	v86.es = VTOPSEG(&smap);
62	v86.edi = VTOPOFF(&smap);
63	v86int();
64	if ((V86_CY(v86.efl)) || (v86.eax != SMAP_SIG))
65	    break;
66	/* look for a low-memory segment that's large enough */
67	if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base == 0) &&
68	    (smap.length >= (512 * 1024)))
69	    bios_basemem = smap.length;
70	/* look for the first segment in 'extended' memory */
71	if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base == 0x100000)) {
72	    bios_extmem = smap.length;
73	}
74
75	/*
76	 * Look for the largest segment in 'extended' memory beyond
77	 * 1MB but below 4GB.
78	 */
79	if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base > 0x100000) &&
80	    (smap.base < 0x100000000ull)) {
81	    size = smap.length;
82
83	    /*
84	     * If this segment crosses the 4GB boundary, truncate it.
85	     */
86	    if (smap.base + size > 0x100000000ull)
87		size = 0x100000000ull - smap.base;
88
89	    if (size > high_heap_size) {
90		high_heap_size = size;
91		high_heap_base = smap.base;
92	    }
93	}
94    } while (v86.ebx != 0);
95
96    /* Fall back to the old compatibility function for base memory */
97    if (bios_basemem == 0) {
98	v86.ctl = 0;
99	v86.addr = 0x12;		/* int 0x12 */
100	v86int();
101
102	bios_basemem = (v86.eax & 0xffff) * 1024;
103    }
104
105    /* Fall back through several compatibility functions for extended memory */
106    if (bios_extmem == 0) {
107	v86.ctl = V86_FLAGS;
108	v86.addr = 0x15;		/* int 0x15 function 0xe801*/
109	v86.eax = 0xe801;
110	v86int();
111	if (!(V86_CY(v86.efl))) {
112	    bios_extmem = ((v86.ecx & 0xffff) + ((v86.edx & 0xffff) * 64)) * 1024;
113	}
114    }
115    if (bios_extmem == 0) {
116	v86.ctl = 0;
117	v86.addr = 0x15;		/* int 0x15 function 0x88*/
118	v86.eax = 0x8800;
119	v86int();
120	bios_extmem = (v86.eax & 0xffff) * 1024;
121    }
122
123    /* Set memtop to actual top of memory */
124    memtop = memtop_copyin = 0x100000 + bios_extmem;
125
126    /*
127     * If we have extended memory and did not find a suitable heap
128     * region in the SMAP, use the last 3MB of 'extended' memory as a
129     * high heap candidate.
130     */
131    if (bios_extmem >= HEAP_MIN && high_heap_size < HEAP_MIN) {
132	high_heap_size = HEAP_MIN;
133	high_heap_base = memtop - HEAP_MIN;
134    }
135}
136