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1.1 root 1: /*
2: * Linux Boot Option ROM
3: *
4: * This program is free software; you can redistribute it and/or modify
5: * it under the terms of the GNU General Public License as published by
6: * the Free Software Foundation; either version 2 of the License, or
7: * (at your option) any later version.
8: *
9: * This program is distributed in the hope that it will be useful,
10: * but WITHOUT ANY WARRANTY; without even the implied warranty of
11: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12: * GNU General Public License for more details.
13: *
14: * You should have received a copy of the GNU General Public License
15: * along with this program; if not, see <http://www.gnu.org/licenses/>.
16: *
17: * Copyright Novell Inc, 2009
18: * Authors: Alexander Graf <[email protected]>
19: *
20: * Based on code in hw/pc.c.
21: */
22:
23: #include "optionrom.h"
24:
1.1.1.4 ! root 25: #define BOOT_ROM_PRODUCT "Linux loader"
! 26:
1.1 root 27: BOOT_ROM_START
28:
29: run_linuxboot:
30:
31: cli
32: cld
33:
34: jmp copy_kernel
35: boot_kernel:
36:
37: read_fw FW_CFG_SETUP_ADDR
38:
39: mov %eax, %ebx
40: shr $4, %ebx
41:
42: /* All segments contain real_addr */
43: mov %bx, %ds
44: mov %bx, %es
45: mov %bx, %fs
46: mov %bx, %gs
47: mov %bx, %ss
48:
49: /* CX = CS we want to jump to */
50: add $0x20, %bx
51: mov %bx, %cx
52:
53: /* SP = cmdline_addr-real_addr-16 */
54: read_fw FW_CFG_CMDLINE_ADDR
55: mov %eax, %ebx
56: read_fw FW_CFG_SETUP_ADDR
57: sub %eax, %ebx
58: sub $16, %ebx
59: mov %ebx, %esp
60:
61: /* Build indirect lret descriptor */
62: pushw %cx /* CS */
63: xor %ax, %ax
64: pushw %ax /* IP = 0 */
65:
66: /* Clear registers */
67: xor %eax, %eax
68: xor %ebx, %ebx
69: xor %ecx, %ecx
70: xor %edx, %edx
71: xor %edi, %edi
72: xor %ebp, %ebp
73:
74: /* Jump to Linux */
75: lret
76:
77:
78: copy_kernel:
79:
80: /* We need to load the kernel into memory we can't access in 16 bit
81: mode, so let's get into 32 bit mode, write the kernel and jump
82: back again. */
83:
84: /* Reserve space on the stack for our GDT descriptor. */
85: mov %esp, %ebp
86: sub $16, %esp
87:
88: /* Now create the GDT descriptor */
89: movw $((3 * 8) - 1), -16(%bp)
90: mov %cs, %eax
1.1.1.2 root 91: movzwl %ax, %eax
1.1 root 92: shl $4, %eax
1.1.1.2 root 93: addl $gdt, %eax
94: movl %eax, -14(%bp)
1.1 root 95:
96: /* And load the GDT */
97: data32 lgdt -16(%bp)
98: mov %ebp, %esp
99:
100: /* Get us to protected mode now */
101: mov $1, %eax
102: mov %eax, %cr0
103:
104: /* So we can set ES to a 32-bit segment */
105: mov $0x10, %eax
106: mov %eax, %es
107:
108: /* We're now running in 16-bit CS, but 32-bit ES! */
109:
110: /* Load kernel and initrd */
1.1.1.3 root 111: read_fw_blob_addr32(FW_CFG_KERNEL)
112: read_fw_blob_addr32(FW_CFG_INITRD)
113: read_fw_blob_addr32(FW_CFG_CMDLINE)
114: read_fw_blob_addr32(FW_CFG_SETUP)
1.1 root 115:
116: /* And now jump into Linux! */
117: mov $0, %eax
118: mov %eax, %cr0
119:
120: /* ES = CS */
121: mov %cs, %ax
122: mov %ax, %es
123:
124: jmp boot_kernel
125:
126: /* Variables */
127:
128: .align 4, 0
129: gdt:
130: /* 0x00 */
131: .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
132:
133: /* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */
134: .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00
135:
136: /* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */
137: .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00
138:
139: BOOT_ROM_END
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