2005-04-16 16:20:36 -06:00
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/*
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* bootsect.S Copyright (C) 1991, 1992 Linus Torvalds
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*
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* modified by Drew Eckhardt
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* modified by Bruce Evans (bde)
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* modified by Chris Noe (May 1999) (as86 -> gas)
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* gutted by H. Peter Anvin (Jan 2003)
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*
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* BIG FAT NOTE: We're in real mode using 64k segments. Therefore segment
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* addresses must be multiplied by 16 to obtain their respective linear
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* addresses. To avoid confusion, linear addresses are written using leading
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* hex while segment addresses are written as segment:offset.
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*
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*/
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#include <asm/boot.h>
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SETUPSECTS = 4 /* default nr of setup-sectors */
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BOOTSEG = 0x07C0 /* original address of boot-sector */
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INITSEG = DEF_INITSEG /* we move boot here - out of the way */
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SETUPSEG = DEF_SETUPSEG /* setup starts here */
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SYSSEG = DEF_SYSSEG /* system loaded at 0x10000 (65536) */
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SYSSIZE = DEF_SYSSIZE /* system size: # of 16-byte clicks */
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/* to be loaded */
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ROOT_DEV = 0 /* ROOT_DEV is now written by "build" */
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SWAP_DEV = 0 /* SWAP_DEV is now written by "build" */
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#ifndef SVGA_MODE
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#define SVGA_MODE ASK_VGA
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#endif
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#ifndef RAMDISK
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#define RAMDISK 0
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#endif
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#ifndef ROOT_RDONLY
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#define ROOT_RDONLY 1
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#endif
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.code16
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.text
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.global _start
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_start:
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# Normalize the start address
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jmpl $BOOTSEG, $start2
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start2:
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movw %cs, %ax
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movw %ax, %ds
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movw %ax, %es
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movw %ax, %ss
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movw $0x7c00, %sp
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sti
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cld
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movw $bugger_off_msg, %si
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msg_loop:
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lodsb
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andb %al, %al
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jz die
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movb $0xe, %ah
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movw $7, %bx
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int $0x10
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jmp msg_loop
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die:
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# Allow the user to press a key, then reboot
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xorw %ax, %ax
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int $0x16
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int $0x19
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# int 0x19 should never return. In case it does anyway,
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# invoke the BIOS reset code...
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ljmp $0xf000,$0xfff0
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bugger_off_msg:
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.ascii "Direct booting from floppy is no longer supported.\r\n"
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.ascii "Please use a boot loader program instead.\r\n"
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.ascii "\n"
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.ascii "Remove disk and press any key to reboot . . .\r\n"
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.byte 0
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2005-05-05 17:16:15 -06:00
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2005-04-16 16:20:36 -06:00
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# Kernel attributes; used by setup
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.org 497
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setup_sects: .byte SETUPSECTS
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root_flags: .word ROOT_RDONLY
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syssize: .word SYSSIZE
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swap_dev: .word SWAP_DEV
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ram_size: .word RAMDISK
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vid_mode: .word SVGA_MODE
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root_dev: .word ROOT_DEV
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boot_flag: .word 0xAA55
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