2 * U-boot - i386 Startup Code
4 * Copyright (c) 2002 Omicron Ceti AB, Daniel Engstr�m <denaiel@omicron.se>
6 * See file CREDITS for list of people who contributed to this
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation; either version 2 of
12 * the License, or (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
33 .type _start, @function
34 .globl _i386boot_start
37 * This is the fail safe 32-bit bootstrap entry point. The
38 * following code is not executed from a cold-reset (actually, a
39 * lot of it is, but from real-mode after cold reset. It is
40 * repeated here to put the board into a state as close to cold
46 /* Turn of cache (this might require a 486-class CPU) */
52 /* Tell 32-bit code it is being entered from an in-RAM copy */
55 /* This is the 32-bit cold-reset entry point */
57 movl $0x18, %eax /* Load our segement registes, the
58 * gdt have already been loaded by start16.S */
65 /* Clear the interupt vectors */
69 * Skip low-level board and memory initialization if not starting
70 * from cold-reset. This allows us to do a fail safe boot-strap
71 * into a new build of U-Boot from a known-good boot flash
77 /* We call a few functions in the board support package
78 * since we have no stack yet we'll have to use %ebp
79 * to store the return address */
81 /* Early platform init (setup gpio, etc ) */
83 .globl early_board_init_ret
91 /* fetch memory size (into %eax) */
93 .globl get_mem_size_ret
96 #if CONFIG_SYS_SDRAM_ECC_ENABLE
97 /* Skip ECC initialization if not starting from cold-reset */
99 andl $GD_FLG_COLD_BOOT, %ecx
107 /* Check we have enough memory for stack */
108 movl $CONFIG_SYS_STACK_SIZE, %ecx
112 /* Set stack pointer to upper memory limit*/
122 cmpl $0x55aa55aa, %ecx
127 /* Set the upper memory limit parameter */
128 subl $CONFIG_SYS_STACK_SIZE, %eax
130 call board_init_f /* Enter, U-boot! */
132 /* indicate (lack of) progress */