2262cfeef9
Add support for i386 architecture and AMD SC520 board * Patch by Pierre Aubert, 12 Nov 2002: Add support for DOS filesystem and booting from DOS floppy disk
113 lines
3.1 KiB
ArmAsm
113 lines
3.1 KiB
ArmAsm
/*
|
|
* U-boot - i386 Startup Code
|
|
*
|
|
* Copyright (c) 2002 Omicron Ceti AB, Daniel Engström <denaiel@omicron.se>
|
|
*
|
|
* See file CREDITS for list of people who contributed to this
|
|
* project.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation; either version 2 of
|
|
* the License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
|
|
* MA 02111-1307 USA
|
|
*/
|
|
|
|
|
|
#define BOOT_SEG 0xffff0000 /* linear segment of boot code */
|
|
#define a32 .byte 0x67;
|
|
#define o32 .byte 0x66;
|
|
|
|
.section .start16, "ax"
|
|
.code16
|
|
.globl start16
|
|
start16:
|
|
/* First we let the BSP do some early initialization
|
|
* this code have to map the flash to its final position
|
|
*/
|
|
mov $board_init16_ret, %bp
|
|
jmp board_init16
|
|
board_init16_ret:
|
|
|
|
/* Turn of cache (this might require a 486-class CPU) */
|
|
movl %cr0, %eax
|
|
orl $060000000,%eax
|
|
movl %eax, %cr0
|
|
wbinvd
|
|
|
|
/* load the descriptor tables */
|
|
o32 cs lidt idt_ptr
|
|
o32 cs lgdt gdt_ptr
|
|
|
|
|
|
/* Now, we enter protected mode */
|
|
movl %cr0, %eax
|
|
orl $1,%eax
|
|
movl %eax, %cr0
|
|
|
|
/* Flush the prefetch queue */
|
|
jmp ff
|
|
ff:
|
|
|
|
/* Finally jump to the 32bit initialization code */
|
|
movw $code32start, %ax
|
|
movw %ax,%bp
|
|
o32 cs ljmp *(%bp)
|
|
|
|
/* 48-bit far pointer */
|
|
code32start:
|
|
.long _start /* offset */
|
|
.word 0x10 /* segment */
|
|
|
|
idt_ptr:
|
|
.word 0 /* limit */
|
|
.long 0 /* base */
|
|
|
|
gdt_ptr:
|
|
.word 0x30 /* limit (48 bytes = 6 GDT entries) */
|
|
.long BOOT_SEG + gdt /* base */
|
|
|
|
/* The GDT table ...
|
|
*
|
|
* Selector Type
|
|
* 0x00 NULL
|
|
* 0x08 Unused
|
|
* 0x10 32bit code
|
|
* 0x18 32bit data/stack
|
|
* 0x20 16bit code
|
|
* 0x28 16bit data/stack
|
|
*/
|
|
|
|
gdt:
|
|
.word 0, 0, 0, 0 /* NULL */
|
|
.word 0, 0, 0, 0 /* unused */
|
|
|
|
.word 0xFFFF /* 4Gb - (0x100000*0x1000 = 4Gb) */
|
|
.word 0 /* base address = 0 */
|
|
.word 0x9B00 /* code read/exec */
|
|
.word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */
|
|
|
|
.word 0xFFFF /* 4Gb - (0x100000*0x1000 = 4Gb) */
|
|
.word 0x0 /* base address = 0 */
|
|
.word 0x9300 /* data read/write */
|
|
.word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */
|
|
|
|
.word 0xFFFF /* 64kb */
|
|
.word 0 /* base address = 0 */
|
|
.word 0x9b00 /* data read/write */
|
|
.word 0x0010 /* granularity = 1 (+5th nibble of limit) */
|
|
|
|
.word 0xFFFF /* 64kb */
|
|
.word 0 /* base address = 0 */
|
|
.word 0x9300 /* data read/write */
|
|
.word 0x0010 /* granularity = 1 (+5th nibble of limit) */
|