1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
; -----------------------------------------------------------------------
;
; Copyright 1999-2008 H. Peter Anvin - All Rights Reserved
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
; Boston MA 02110-1301, USA; either version 2 of the License, or
; (at your option) any later version; incorporated herein by reference.
;
; -----------------------------------------------------------------------
;
; localboot.inc
;
; Boot from a local disk, or invoke INT 18h.
;
%if HAS_LOCALBOOT
;
; Boot a specified local disk. AX specifies the BIOS disk number; or
; -1 in case we should execute INT 18h ("next device.")
;
section .text
local_boot:
call vgaclearmode
RESET_STACK_AND_SEGS dx ; dx <- 0
mov fs,dx
mov gs,dx
mov si,localboot_msg
call writestr
cmp ax,-1
je .int18
; Load boot sector from the specified BIOS device and jump to it.
mov dl,al
xor dh,dh
push dx
xor ax,ax ; Reset drive
int 13h
mov ax,0201h ; Read one sector
mov cx,0001h ; C/H/S = 0/0/1 (first sector)
mov bx,trackbuf
mov bp,retry_count
.again:
pusha
int 13h
popa
jnc .ok
dec bp
jnz .again
jmp kaboom ; Failure...
.ok:
pop dx
cli ; Abandon hope, ye who enter here
mov si,trackbuf
mov di,07C00h
mov cx,512 ; Probably overkill, but should be safe
rep movsd
mov ss,cx ; SS <- 0
mov sp,7C00h
jmp 0:07C00h ; Jump to new boot sector
.int18:
int 18h ; Hope this does the right thing...
jmp kaboom ; If we returned, oh boy...
section .data
localboot_msg db 'Booting from local disk...', CR, LF, 0
section .text
%endif ; HAS_LOCALBOOT
|
