1; ----------------------------------------------------------------------- 2; 3; Copyright 1999-2008 H. Peter Anvin - All Rights Reserved 4; 5; This program is free software; you can redistribute it and/or modify 6; it under the terms of the GNU General Public License as published by 7; the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, 8; Boston MA 02110-1301, USA; either version 2 of the License, or 9; (at your option) any later version; incorporated herein by reference. 10; 11; ----------------------------------------------------------------------- 12 13; 14; localboot.inc 15; 16; Boot from a local disk, or invoke INT 18h. 17; 18 19; 20; Boot a specified local disk. AX specifies the BIOS disk number; or 21; -1 in case we should execute INT 18h ("next device.") 22; 23 section .text16 24 25local_boot: 26 call vgaclearmode 27 RESET_STACK_AND_SEGS dx ; dx <- 0 28 mov fs,dx 29 mov gs,dx 30 mov si,localboot_msg 31 call writestr 32 call cleanup_hardware 33 cmp ax,-1 34 je .int18 35 36 ; Load boot sector from the specified BIOS device and jump to it. 37 mov dl,al 38 xor dh,dh 39 push dx 40 xor ax,ax ; Reset drive 41 int 13h 42 mov ax,0201h ; Read one sector 43 mov cx,0001h ; C/H/S = 0/0/1 (first sector) 44 mov bx,trackbuf 45 mov bp,retry_count 46.again: 47 pusha 48 int 13h 49 popa 50 jnc .ok 51 dec bp 52 jnz .again 53 jmp kaboom ; Failure... 54.ok: 55 pop dx 56 cli ; Abandon hope, ye who enter here 57 mov si,trackbuf 58 mov di,07C00h 59 mov cx,512 ; Probably overkill, but should be safe 60 rep movsd 61 mov ss,cx ; SS <- 0 62 mov sp,7C00h 63 jmp 0:07C00h ; Jump to new boot sector 64 65.int18: 66 int 18h ; Hope this does the right thing... 67 jmp kaboom ; If we returned, oh boy... 68 69 section .data16 70localboot_msg db 'Booting from local disk...', CR, LF, 0 71 72 section .text16 73 74