biosmem.c revision 173118
1227825Stheraven/*- 2227825Stheraven * Copyright (c) 1998 Michael Smith <msmith@freebsd.org> 3227825Stheraven * All rights reserved. 4227825Stheraven * 5227825Stheraven * Redistribution and use in source and binary forms, with or without 6227825Stheraven * modification, are permitted provided that the following conditions 7227825Stheraven * are met: 8227825Stheraven * 1. Redistributions of source code must retain the above copyright 9227825Stheraven * notice, this list of conditions and the following disclaimer. 10227825Stheraven * 2. Redistributions in binary form must reproduce the above copyright 11227825Stheraven * notice, this list of conditions and the following disclaimer in the 12227825Stheraven * documentation and/or other materials provided with the distribution. 13227825Stheraven * 14227825Stheraven * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15227825Stheraven * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16227825Stheraven * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17227825Stheraven * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18227825Stheraven * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19227825Stheraven * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20227825Stheraven * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21227825Stheraven * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22227825Stheraven * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23227825Stheraven * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24227825Stheraven * SUCH DAMAGE. 25227825Stheraven */ 26227825Stheraven 27227825Stheraven#include <sys/cdefs.h> 28227825Stheraven__FBSDID("$FreeBSD: head/sys/boot/i386/libi386/biosmem.c 173118 2007-10-28 21:23:49Z jhb $"); 29227825Stheraven 30227825Stheraven/* 31227825Stheraven * Obtain memory configuration information from the BIOS 32227825Stheraven */ 33227825Stheraven#include <stand.h> 34227825Stheraven#include <machine/pc/bios.h> 35227825Stheraven#include "libi386.h" 36227825Stheraven#include "btxv86.h" 37227825Stheraven 38227825Stheravenvm_offset_t memtop, memtop_copyin; 39227825Stheravenu_int32_t bios_basemem, bios_extmem; 40227825Stheraven 41227825Stheravenstatic struct bios_smap smap; 42227825Stheraven 43227825Stheravenvoid 44227825Stheravenbios_getmem(void) 45227825Stheraven{ 46227825Stheraven 47227825Stheraven /* Parse system memory map */ 48227825Stheraven v86.ebx = 0; 49227825Stheraven do { 50227825Stheraven v86.ctl = V86_FLAGS; 51227825Stheraven v86.addr = 0x15; /* int 0x15 function 0xe820*/ 52227825Stheraven v86.eax = 0xe820; 53227825Stheraven v86.ecx = sizeof(struct bios_smap); 54227825Stheraven v86.edx = SMAP_SIG; 55227825Stheraven v86.es = VTOPSEG(&smap); 56227825Stheraven v86.edi = VTOPOFF(&smap); 57227825Stheraven v86int(); 58227825Stheraven if ((v86.efl & 1) || (v86.eax != SMAP_SIG)) 59227825Stheraven break; 60227825Stheraven /* look for a low-memory segment that's large enough */ 61227825Stheraven if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base == 0) && 62227825Stheraven (smap.length >= (512 * 1024))) 63227825Stheraven bios_basemem = smap.length; 64227825Stheraven /* look for the first segment in 'extended' memory */ 65227825Stheraven if ((smap.type == SMAP_TYPE_MEMORY) && (smap.base == 0x100000)) { 66227825Stheraven bios_extmem = smap.length; 67227825Stheraven } 68227825Stheraven } while (v86.ebx != 0); 69227825Stheraven 70227825Stheraven /* Fall back to the old compatibility function for base memory */ 71227825Stheraven if (bios_basemem == 0) { 72227825Stheraven v86.ctl = 0; 73227825Stheraven v86.addr = 0x12; /* int 0x12 */ 74227825Stheraven v86int(); 75227825Stheraven 76227825Stheraven bios_basemem = (v86.eax & 0xffff) * 1024; 77227825Stheraven } 78227825Stheraven 79227825Stheraven /* Fall back through several compatibility functions for extended memory */ 80227825Stheraven if (bios_extmem == 0) { 81227825Stheraven v86.ctl = V86_FLAGS; 82227825Stheraven v86.addr = 0x15; /* int 0x15 function 0xe801*/ 83227825Stheraven v86.eax = 0xe801; 84227825Stheraven v86int(); 85227825Stheraven if (!(v86.efl & 1)) { 86227825Stheraven bios_extmem = ((v86.ecx & 0xffff) + ((v86.edx & 0xffff) * 64)) * 1024; 87227825Stheraven } 88227825Stheraven } 89227825Stheraven if (bios_extmem == 0) { 90227825Stheraven v86.ctl = 0; 91227825Stheraven v86.addr = 0x15; /* int 0x15 function 0x88*/ 92227825Stheraven v86.eax = 0x8800; 93227825Stheraven v86int(); 94227825Stheraven bios_extmem = (v86.eax & 0xffff) * 1024; 95227825Stheraven } 96227825Stheraven 97227825Stheraven /* Set memtop to actual top of memory */ 98227825Stheraven memtop = memtop_copyin = 0x100000 + bios_extmem; 99227825Stheraven 100227825Stheraven} 101227825Stheraven 102227825Stheraven