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/*
* head.S for bootstub to load protected mode kernel
*
* Copyright (C) 2008-2010 Intel Corporation.
* Author: Alek Du <alek.du@intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
/*
*
* Note. When FW hand-off control to bootstub, the CPU is already in protected
* Mode with 1. GDT(8)=4G GDT(10)=4G
* 2. CS=8, DS=ES=FS=GS=10
* 3. Paging mode disabled
* 4. Interrupt ENABLED
*
* When bootstub get control, the memory map in DRAM is like:
* ~ ~
* 0x1102000 | initrd | initrd will move to highest memory otherwise
*+bzImage size +-----------------------+ bzImage uncompressing will destory it
* | bzImage |
* 0x1102000 +-----------------------+
* | boot stub |
* 0x1101000 +-----------------------+
* | free space |
* | used as stack |
* 0x1100110 +-----------------------+
* | SPI0 or SPI1 | MIC need to fill it:
* | | 0x0: SPI0, 0x1: SPI1
* 0x110010c +-----------------------+
* | boot stub spi uart | MIC need to fill it:
* | suppression flag | 0x1 suppression, 0x0 default
* 0x1100108 +-----------------------+
* | initrd size | MIC need to fill it: initrd file size
* 0x1100104 +-----------------------+
* | bzImage size | MIC need to fill it: bzImage file size
* 0x1100100 +-----------------------+
* | kernel cmdline | MIC need to fill it
* 0x1100000 +-----------------------+
*/
#include "bootstub.h"
.text
.section ".text.head","ax",@progbits
.globl _start
_start:
cld
cli
/* setup stack, because we are heading off to "C" */
movl $STACK_OFFSET, %esp
/* after call bootstub, GDT was set (0x10 and 0x18) IDT was clear
* eax will store 32bit entry of bzImage
*/
calll bootstub
/* DS=ES=FS=GS=10 */
movl $__BOOT_DS, %ebx
movl %ebx, %ds
movl %ebx, %es
movl %ebx, %fs
movl %ebx, %gs
movl %ebx, %ss
ljmp $__BOOT_CS,$1f
1:
/* tell kernel where is boot_param */
movl $(BOOT_PARAMS_OFFSET), %esi
xor %ebp, %ebp
xor %edi, %edi
xor %ebx, %ebx
jmpl *%eax # Jump to the 32-bit entrypoint
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