biosmemx.S revision 1.13
1 /* $NetBSD: biosmemx.S,v 1.13 2024/08/24 20:23:11 riastradh Exp $ */ 2 3 /* 4 * Copyright (c) 1997, 1999 5 * Matthias Drochner. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29 #include <machine/asm.h> 30 31 .text 32 33 /* 34 * int getextmem2(int buffer[2]) 35 * 36 * return: 0=OK, -1=error 37 * buffer[0]: extmem kBytes below 16M (max 15M/1024) 38 * buffer[1]: extmem above 16M, in 64k units 39 */ 40 ENTRY(getextmem2) 41 pushl %ebp 42 movl %esp,%ebp 43 pushl %ebx 44 pushl %ecx 45 pushl %edx 46 push %esi 47 push %edi 48 49 call _C_LABEL(prot_to_real) 50 .code16 51 52 xorl %ebx,%ebx 53 movl $0xe801,%eax 54 int $0x15 55 pushf 56 57 movw %si,%ax 58 orw %si,%bx 59 jz 1f /* if zero use configured values */ 60 movw %cx,%ax /* k below 16M (max 0x3c00 = 15MB) */ 61 movw %dx,%bx /* 64k above 16M */ 62 1: 63 popf 64 setc %bl 65 66 calll _C_LABEL(real_to_prot) 67 .code32 68 69 movl 8(%ebp),%edi 70 xorl %eax,%eax 71 movw %cx,%ax 72 stosl 73 movw %dx,%ax 74 stosl 75 movb %bl,%al 76 cbw 77 78 pop %edi 79 pop %esi 80 popl %edx 81 popl %ecx 82 popl %ebx 83 popl %ebp 84 ret 85 86 /* 87 * int getmementry(int *iterator, int buffer[6]) 88 * 89 * return: 0=ok, else error 90 * buffer[0]: start of memory chunk 91 * buffer[2]: length (bytes) 92 * buffer[4]: type 93 * buffer[5]: ACPI 3.0 Extended Attributes bitfield (unused) 94 * 95 * Some buggy BIOSes may write to 24 bytes even if only 20 were requested. 96 * Therefore, the buffer is defined for 6 elements to avoid stack buffer 97 * overruns. See PR install/49470. 98 * 99 * More details can be found in the: 100 * 101 * Advanced Configuration and Power Interface (ACPI) 102 * Specification, Release 6.5, 2022-08-29, UEFI Forum, Inc., 103 * Sec. 15.1 `INT 15H E820H - Query System Address Map', 104 * pp. 756-757 105 * https://uefi.org/sites/default/files/resources/ACPI_Spec_6_5_Aug29.pdf#page=824 106 * https://uefi.org/specs/ACPI/6.5/15_System_Address_Map_Interfaces.html#int-15h-e820h-query-system-address-map 107 * 108 * as well as this OSDev.org wiki page: 109 * 110 * https://wiki.osdev.org/Detecting_Memory_(x86)#BIOS_Function:_INT_0x15,_EAX_=_0xE820 111 */ 112 ENTRY(getmementry) 113 pushl %ebp 114 movl %esp,%ebp 115 pushl %ebx 116 pushl %ecx 117 pushl %edx 118 push %esi 119 push %edi 120 121 movl 8(%ebp),%eax 122 movl 0(%eax),%ebx /* index */ 123 movl $20,%ecx /* Buffer size */ 124 movl $0x534d4150,%edx /* "SMAP" */ 125 movl 12(%ebp),%edi /* buffer address */ 126 127 call _C_LABEL(prot_to_real) 128 .code16 129 130 push %di 131 shrl $4,%edi 132 mov %ds,%ax 133 add %di,%ax 134 mov %ax,%es 135 pop %di 136 and $0xf,%di /* buffer address now in ES:DI */ 137 138 movl $0xe820,%eax /* Some BIOS check EAX value */ 139 int $0x15 140 141 setc %cl 142 143 calll _C_LABEL(real_to_prot) 144 .code32 145 146 movl 8(%ebp),%eax 147 movl %ebx,0(%eax) /* updated index */ 148 xorl %eax,%eax 149 movb %cl,%al 150 151 pop %edi 152 pop %esi 153 popl %edx 154 popl %ecx 155 popl %ebx 156 popl %ebp 157 ret 158 159 /* 160 * int biosA20(void) 161 * 162 * return: 0=ok, else error 163 */ 164 ENTRY(biosA20) 165 pushl %ebp 166 movl %esp,%ebp 167 pushl %ebx 168 pushl %ecx 169 pushl %edx 170 push %esi 171 push %edi 172 173 call _C_LABEL(prot_to_real) 174 .code16 175 176 movl $0x2401,%eax 177 int $0x15 178 setc %cl 179 180 calll _C_LABEL(real_to_prot) 181 .code32 182 183 movzbl %cl,%eax 184 185 pop %edi 186 pop %esi 187 popl %edx 188 popl %ecx 189 popl %ebx 190 popl %ebp 191 ret 192
Indexes created Tue Sep 30 11:09:46 GMT 2025