diff options
Diffstat (limited to 'arch/i386/boot/bootsect.S')
-rw-r--r-- | arch/i386/boot/bootsect.S | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/arch/i386/boot/bootsect.S b/arch/i386/boot/bootsect.S new file mode 100644 index 000000000000..ba9fe14db6a9 --- /dev/null +++ b/arch/i386/boot/bootsect.S | |||
@@ -0,0 +1,98 @@ | |||
1 | /* | ||
2 | * bootsect.S Copyright (C) 1991, 1992 Linus Torvalds | ||
3 | * | ||
4 | * modified by Drew Eckhardt | ||
5 | * modified by Bruce Evans (bde) | ||
6 | * modified by Chris Noe (May 1999) (as86 -> gas) | ||
7 | * gutted by H. Peter Anvin (Jan 2003) | ||
8 | * | ||
9 | * BIG FAT NOTE: We're in real mode using 64k segments. Therefore segment | ||
10 | * addresses must be multiplied by 16 to obtain their respective linear | ||
11 | * addresses. To avoid confusion, linear addresses are written using leading | ||
12 | * hex while segment addresses are written as segment:offset. | ||
13 | * | ||
14 | */ | ||
15 | |||
16 | #include <asm/boot.h> | ||
17 | |||
18 | SETUPSECTS = 4 /* default nr of setup-sectors */ | ||
19 | BOOTSEG = 0x07C0 /* original address of boot-sector */ | ||
20 | INITSEG = DEF_INITSEG /* we move boot here - out of the way */ | ||
21 | SETUPSEG = DEF_SETUPSEG /* setup starts here */ | ||
22 | SYSSEG = DEF_SYSSEG /* system loaded at 0x10000 (65536) */ | ||
23 | SYSSIZE = DEF_SYSSIZE /* system size: # of 16-byte clicks */ | ||
24 | /* to be loaded */ | ||
25 | ROOT_DEV = 0 /* ROOT_DEV is now written by "build" */ | ||
26 | SWAP_DEV = 0 /* SWAP_DEV is now written by "build" */ | ||
27 | |||
28 | #ifndef SVGA_MODE | ||
29 | #define SVGA_MODE ASK_VGA | ||
30 | #endif | ||
31 | |||
32 | #ifndef RAMDISK | ||
33 | #define RAMDISK 0 | ||
34 | #endif | ||
35 | |||
36 | #ifndef ROOT_RDONLY | ||
37 | #define ROOT_RDONLY 1 | ||
38 | #endif | ||
39 | |||
40 | .code16 | ||
41 | .text | ||
42 | |||
43 | .global _start | ||
44 | _start: | ||
45 | |||
46 | # Normalize the start address | ||
47 | jmpl $BOOTSEG, $start2 | ||
48 | |||
49 | start2: | ||
50 | movw %cs, %ax | ||
51 | movw %ax, %ds | ||
52 | movw %ax, %es | ||
53 | movw %ax, %ss | ||
54 | movw $0x7c00, %sp | ||
55 | sti | ||
56 | cld | ||
57 | |||
58 | movw $bugger_off_msg, %si | ||
59 | |||
60 | msg_loop: | ||
61 | lodsb | ||
62 | andb %al, %al | ||
63 | jz die | ||
64 | movb $0xe, %ah | ||
65 | movw $7, %bx | ||
66 | int $0x10 | ||
67 | jmp msg_loop | ||
68 | |||
69 | die: | ||
70 | # Allow the user to press a key, then reboot | ||
71 | xorw %ax, %ax | ||
72 | int $0x16 | ||
73 | int $0x19 | ||
74 | |||
75 | # int 0x19 should never return. In case it does anyway, | ||
76 | # invoke the BIOS reset code... | ||
77 | ljmp $0xf000,$0xfff0 | ||
78 | |||
79 | |||
80 | bugger_off_msg: | ||
81 | .ascii "Direct booting from floppy is no longer supported.\r\n" | ||
82 | .ascii "Please use a boot loader program instead.\r\n" | ||
83 | .ascii "\n" | ||
84 | .ascii "Remove disk and press any key to reboot . . .\r\n" | ||
85 | .byte 0 | ||
86 | |||
87 | |||
88 | # Kernel attributes; used by setup | ||
89 | |||
90 | .org 497 | ||
91 | setup_sects: .byte SETUPSECTS | ||
92 | root_flags: .word ROOT_RDONLY | ||
93 | syssize: .word SYSSIZE | ||
94 | swap_dev: .word SWAP_DEV | ||
95 | ram_size: .word RAMDISK | ||
96 | vid_mode: .word SVGA_MODE | ||
97 | root_dev: .word ROOT_DEV | ||
98 | boot_flag: .word 0xAA55 | ||