blob: b1fa050f86d4efb2f5afc6b7ab549a35f14bf511 [file] [log] [blame]
// 16bit code to load disk image and start system boot.
//
// Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2002 MandrakeSoft S.A.
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "util.h" // irq_enable
#include "biosvar.h" // struct bregs
#include "config.h" // CONFIG_*
#include "cmos.h" // inb_cmos
#include "ata.h" // ata_detect
#include "disk.h" // cdrom_boot
// We need a copy of this string, but we are not actually a PnP BIOS,
// so make sure it is *not* aligned, so OSes will not see it if they
// scan.
char pnp_string[] VISIBLE16 __attribute__((aligned (2))) = " $PnP";
//--------------------------------------------------------------------------
// print_boot_device
// displays the boot device
//--------------------------------------------------------------------------
static const char drivetypes[][10]={
"", "Floppy","Hard Disk","CD-Rom", "Network"
};
static void
print_boot_device(u16 type)
{
/* NIC appears as type 0x80 */
if (type == IPL_TYPE_BEV)
type = 0x4;
if (type == 0 || type > 0x4)
BX_PANIC("Bad drive type\n");
printf("Booting from %s...\n", drivetypes[type]);
// XXX - latest cvs has BEV description
}
//--------------------------------------------------------------------------
// print_boot_failure
// displays the reason why boot failed
//--------------------------------------------------------------------------
static void
print_boot_failure(u16 type, u8 reason)
{
if (type == 0 || type > 0x3)
BX_PANIC("Bad drive type\n");
printf("Boot failed");
if (type < 4) {
/* Report the reason too */
if (reason==0)
printf(": not a bootable disk");
else
printf(": could not read the boot disk");
}
printf("\n\n");
}
static void
try_boot(u16 seq_nr)
{
SET_IPL(sequence, seq_nr);
u16 bootseg;
u8 bootdrv = 0;
u16 bootdev, bootip;
if (CONFIG_CDROM_BOOT) {
bootdev = inb_cmos(CMOS_BIOS_BOOTFLAG2);
bootdev |= ((inb_cmos(CMOS_BIOS_BOOTFLAG1) & 0xf0) << 4);
bootdev >>= 4 * seq_nr;
bootdev &= 0xf;
if (bootdev == 0)
BX_PANIC("No bootable device.\n");
/* Translate from CMOS runes to an IPL table offset by subtracting 1 */
bootdev -= 1;
} else {
if (seq_nr ==2)
BX_PANIC("No more boot devices.");
if (!!(inb_cmos(CMOS_BIOS_CONFIG) & 0x20) ^ (seq_nr == 1))
/* Boot from floppy if the bit is set or it's the second boot */
bootdev = 0x00;
else
bootdev = 0x01;
}
if (bootdev >= GET_IPL(count)) {
BX_INFO("Invalid boot device (0x%x)\n", bootdev);
return;
}
u16 type = GET_IPL(table[bootdev].type);
/* Do the loading, and set up vector as a far pointer to the boot
* address, and bootdrv as the boot drive */
print_boot_device(type);
struct bregs cr;
switch(type) {
case IPL_TYPE_FLOPPY: /* FDD */
case IPL_TYPE_HARDDISK: /* HDD */
bootdrv = (type == IPL_TYPE_HARDDISK) ? 0x80 : 0x00;
bootseg = 0x07c0;
// Read sector
memset(&cr, 0, sizeof(cr));
cr.dl = bootdrv;
cr.es = bootseg;
cr.ah = 2;
cr.al = 1;
cr.cl = 1;
call16_int(0x13, &cr);
if (cr.flags & F_CF) {
print_boot_failure(type, 1);
return;
}
/* Always check the signature on a HDD boot sector; on FDD,
* only do the check if the CMOS doesn't tell us to skip it */
if ((type != IPL_TYPE_FLOPPY)
|| !((inb_cmos(CMOS_BIOS_BOOTFLAG1) & 0x01))) {
if (GET_FARVAR(bootseg, *(u16*)0x1fe) != 0xaa55) {
print_boot_failure(type, 0);
return;
}
}
/* Canonicalize bootseg:bootip */
bootip = (bootseg & 0x0fff) << 4;
bootseg &= 0xf000;
break;
case IPL_TYPE_CDROM: {
/* CD-ROM */
if (! CONFIG_CDROM_BOOT)
break;
u16 status = cdrom_boot();
if (status) {
printf("CDROM boot failure code : %04x\n", status);
print_boot_failure(type, 1);
return;
}
bootdrv = GET_EBDA(cdemu.emulated_drive);
bootseg = GET_EBDA(cdemu.load_segment);
/* Canonicalize bootseg:bootip */
bootip = (bootseg & 0x0fff) << 4;
bootseg &= 0xf000;
break;
}
case IPL_TYPE_BEV: {
/* Expansion ROM with a Bootstrap Entry Vector (a far
* pointer) */
u32 vector = GET_IPL(table[bootdev].vector);
bootseg = vector >> 16;
bootip = vector & 0xffff;
break;
}
default:
return;
}
/* Debugging info */
BX_INFO("Booting from %x:%x\n", bootseg, bootip);
memset(&cr, 0, sizeof(cr));
cr.ip = bootip;
cr.cs = bootseg;
// Set the magic number in ax and the boot drive in dl.
cr.dl = bootdrv;
cr.ax = 0xaa55;
call16(&cr);
}
static void
do_boot(u16 seq_nr)
{
try_boot(seq_nr);
// Boot failed: invoke the boot recovery function
struct bregs br;
memset(&br, 0, sizeof(br));
call16_int(0x18, &br);
}
// Boot Failure recovery: try the next device.
void VISIBLE16
handle_18()
{
debug_enter(NULL);
u16 seq = GET_IPL(sequence) + 1;
do_boot(seq);
}
// INT 19h Boot Load Service Entry Point
void VISIBLE16
handle_19()
{
debug_enter(NULL);
do_boot(0);
}
// Called from 32bit code - start boot process
void VISIBLE16
begin_boot()
{
if (CONFIG_ATA)
ata_detect();
irq_enable();
struct bregs br;
memset(&br, 0, sizeof(br));
call16_int(0x19, &br);
}