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// 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 LGPLv3 license.
#include "util.h" // irq_enable
#include "biosvar.h" // GET_EBDA
#include "config.h" // CONFIG_*
#include "disk.h" // cdrom_boot
#include "bregs.h" // struct bregs
#include "boot.h" // struct ipl_s
struct ipl_s IPL;
//--------------------------------------------------------------------------
// print_boot_device
// displays the boot device
//--------------------------------------------------------------------------
static const char drivetypes[][10]={
"", "Floppy", "Hard Disk", "CD-Rom", "Network"
};
void
printf_bootdev(u16 bootdev)
{
u16 type = IPL.table[bootdev].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("%s", drivetypes[type]);
/* print product string if BEV */
char *description_fl = IPL.table[bootdev].description;
if (type == 4 && description_fl != 0) {
char description[33];
/* first 32 bytes are significant */
memcpy(description, description_fl, 32);
/* terminate string */
description[32] = 0;
printf(" [%.s]", description);
}
}
static void
print_boot_device(u16 bootdev)
{
printf("Booting from ");
printf_bootdev(bootdev);
printf("...\n");
}
//--------------------------------------------------------------------------
// 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)
{
if (! CONFIG_BOOT)
BX_PANIC("Boot support not compiled in.\n");
u32 bootdev = IPL.bootorder;
bootdev >>= 4 * seq_nr;
bootdev &= 0xf;
if (bootdev == 0)
BX_PANIC("No bootable device.\n");
/* Translate bootdev to an IPL table offset by subtracting 1 */
bootdev -= 1;
if (bootdev >= IPL.count) {
dprintf(1, "Invalid boot device (0x%x)\n", bootdev);
return;
}
/* Do the loading, and set up vector as a far pointer to the boot
* address, and bootdrv as the boot drive */
print_boot_device(bootdev);
u16 type = IPL.table[bootdev].type;
u16 bootseg, bootip;
u8 bootdrv = 0;
struct bregs cr;
switch(type) {
case IPL_TYPE_FLOPPY:
case IPL_TYPE_HARDDISK:
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 configured for it */
if (type != IPL_TYPE_FLOPPY || IPL.checkfloppysig) {
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)
return;
int status = cdrom_boot();
if (status) {
printf("CDROM boot failure code : %04x\n", status);
print_boot_failure(type, 1);
return;
}
u16 ebda_seg = get_ebda_seg();
bootdrv = GET_EBDA2(ebda_seg, cdemu.emulated_drive);
bootseg = GET_EBDA2(ebda_seg, 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 = IPL.table[bootdev].vector;
bootseg = vector >> 16;
bootip = vector & 0xffff;
break;
}
default:
return;
}
/* Debugging info */
dprintf(1, "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 VISIBLE32
handle_18()
{
debug_serial_setup();
debug_enter(NULL, DEBUG_HDL_18);
u16 ebda_seg = get_ebda_seg();
u16 seq = GET_EBDA2(ebda_seg, boot_sequence) + 1;
SET_EBDA2(ebda_seg, boot_sequence, seq);
do_boot(seq);
}
// INT 19h Boot Load Service Entry Point
void VISIBLE32
handle_19()
{
debug_serial_setup();
debug_enter(NULL, DEBUG_HDL_19);
SET_EBDA(boot_sequence, 0);
do_boot(0);
}
// Ughh - some older gcc compilers have a bug which causes VISIBLE32
// functions to not be exported as global variables.
asm(".global handle_18, handle_19");
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