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