summaryrefslogtreecommitdiff
path: root/src/cpu/x86/32bit/entry32.inc
blob: b016f8eb160a2a4f84ff8476fc2d73da130e14fb (plain)
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
63
64
65
/* For starting coreboot in protected mode */

#include <arch/rom_segs.h>
#include <cpu/x86/post_code.h>

	.code32


	/* This is the GDT for the ROM stage part of coreboot. It
	 * is different from the RAM stage GDT which is defined in
	 * c_start.S
	 */

	.align	4
.globl gdtptr
gdt:
gdtptr:
	.word	gdt_end - gdt -1 /* compute the table limit */
	.long	gdt		 /* we know the offset */
	.word	0

	/* selgdt 0x08, flat code segment */
	.word	0xffff, 0x0000
	.byte	0x00, 0x9b, 0xcf, 0x00 /* G=1 and 0x0f, So we get 4Gbytes for limit */

	/* selgdt 0x10,flat data segment */
	.word	0xffff, 0x0000
	.byte	0x00, 0x93, 0xcf, 0x00

gdt_end:


/*
 *	When we come here we are in protected mode. We expand
 *	the stack and copies the data segment from ROM to the
 *	memory.
 *
 *	After that, we call the chipset bootstrap routine that
 *	does what is left of the chipset initialization.
 *
 *	NOTE aligned to 4 so that we are sure that the prefetch
 *	cache will be reloaded.
 */
	.align	4
.globl protected_start
protected_start:

	lgdt	%cs:gdtptr
	ljmp	$ROM_CODE_SEG, $__protected_start

__protected_start:
	/* Save the BIST value */
	movl	%eax, %ebp

	post_code(POST_ENTER_PROTECTED_MODE)

	movw	$ROM_DATA_SEG, %ax
	movw	%ax, %ds
	movw	%ax, %es
	movw	%ax, %ss
	movw	%ax, %fs
	movw	%ax, %gs

	/* Restore the BIST value to %eax */
	movl	%ebp, %eax