1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
/* head.S for bootstub to load protected mode kernel
* Copyright (C) 2008 Alek Du <alek.du@intel.com>
*
* 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:
* ~ ~
* 0x102000 | initrd | initrd will move to highest memory otherwise
*+bzImage size +-----------------------+ bzImage uncompressing will destory it
* | bzImage |
* 0x102000 +-----------------------+
* | boot stub |
* 0x101000 +-----------------------+
* | free space |
* | used as stack |
* 0x100108 +-----------------------+
* | initrd size | MIC need to fill it according to bzImage size
* 0x100104 +-----------------------+
* | bzImage size | MIC need to fill it according to initrd size
* 0x100100 +-----------------------+
* | kernel cmdline | MIC need to fill it
* 0x100000 +-----------------------+
*/
#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
|
