boot - Hack workarounds for chromebook 'SeaBIOS' issues
[dragonfly.git] / sys / boot / pc32 / libi386 / biosmem.c
CommitLineData
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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 *
5ee58eed 26 * $FreeBSD: src/sys/boot/i386/libi386/biosmem.c,v 1.7 2003/08/25 23:28:31 obrien Exp $
ccf331f0 27 * $DragonFly: src/sys/boot/pc32/libi386/biosmem.c,v 1.4 2004/06/26 02:26:22 dillon Exp $
984263bc 28 */
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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;
ccf331f0 37u_int32_t bios_basemem, bios_extmem, bios_howmem;
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38
39#define SMAPSIG 0x534D4150
40
41struct smap {
42 u_int64_t base;
43 u_int64_t length;
44 u_int32_t type;
5ee58eed 45} __packed;
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46
47static struct smap smap;
48
49void
50bios_getmem(void)
51{
5fc9dc6d 52 int64_t v;
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53
54 /* Parse system memory map */
55 v86.ebx = 0;
56 do {
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57#ifdef COMCONSOLE_DEBUG
58 printf("GET SMAP %d: ", v86.ebx);
59#endif
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60 v86.ctl = V86_FLAGS;
61 v86.addr = 0x15; /* int 0x15 function 0xe820*/
62 v86.eax = 0xe820;
63 v86.ecx = sizeof(struct smap);
64 v86.edx = SMAPSIG;
65 v86.es = VTOPSEG(&smap);
66 v86.edi = VTOPOFF(&smap);
67 v86int();
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68#ifdef COMCONSOLE_DEBUG
69 printf("RESULT: EFL=%04x EAX=%08x SMAPTYPE %d BASE %08x%08x LEN %08x%08x\n",
70 v86.efl, v86.eax, smap.type,
71 (int)(smap.base >> 32), (int)smap.base,
72 (int)(smap.length >> 32), (int)smap.length);
73#endif
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74 if ((v86.efl & 1) || (v86.eax != SMAPSIG))
75 break;
76 /* look for a low-memory segment that's large enough */
ccf331f0 77 if ((smap.type == 1) && (smap.base == 0) && (smap.length >= (512 * 1024))) {
984263bc 78 bios_basemem = smap.length;
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79 bios_howmem = 1;
80 }
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81 /* look for the first segment in 'extended' memory */
82 if ((smap.type == 1) && (smap.base == 0x100000)) {
83 bios_extmem = smap.length;
84 }
85 } while (v86.ebx != 0);
86
87 /* Fall back to the old compatibility function for base memory */
88 if (bios_basemem == 0) {
89 v86.ctl = 0;
90 v86.addr = 0x12; /* int 0x12 */
91 v86int();
92
93 bios_basemem = (v86.eax & 0xffff) * 1024;
ccf331f0 94 bios_howmem = 2;
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95 }
96
97 /* Fall back through several compatibility functions for extended memory */
98 if (bios_extmem == 0) {
99 v86.ctl = V86_FLAGS;
100 v86.addr = 0x15; /* int 0x15 function 0xe801*/
101 v86.eax = 0xe801;
102 v86int();
103 if (!(v86.efl & 1)) {
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104 v = ((v86.ecx & 0xffff) +
105 ((int64_t)(v86.edx & 0xffff) * 64)) * 1024;
106 if (v > 0x40000000)
107 v = 0x40000000;
108 bios_extmem = v;
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109 }
110 }
111 if (bios_extmem == 0) {
112 v86.ctl = 0;
113 v86.addr = 0x15; /* int 0x15 function 0x88*/
114 v86.eax = 0x8800;
115 v86int();
116 bios_extmem = (v86.eax & 0xffff) * 1024;
117 }
118
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119 /*
120 * Set memtop to actual top of memory
121 *
122 * This is broken because the boot loader generally needs more than 16MB
123 * now but the extmem usually calculates to ~14-16MB (which is the fully
124 * segmented limit). Disk I/O will use bounce buffers.
125 *
126 * Hack it for now.
127 */
128 memtop = 0x100000 + bios_extmem; /* XXX ignored */
129 memtop = 64 * 1024 * 1024;
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130}
131