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|
; -*- fundamental -*- (asm-mode sucks)
; ****************************************************************************
;
; ldlinux.asm
;
; A program to boot Linux kernels off an MS-DOS formatted floppy disk. This
; functionality is good to have for installation floppies, where it may
; be hard to find a functional Linux system to run LILO off.
;
; This program allows manipulation of the disk to take place entirely
; from MS-LOSS, and can be especially useful in conjunction with the
; umsdos filesystem.
;
; Copyright 1994-2009 H. Peter Anvin - All Rights Reserved
; Copyright 2009 Intel Corporation; author: H. Peter Anvin
;
; 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., 53 Temple Place Ste 330,
; Boston MA 02111-1307, USA; either version 2 of the License, or
; (at your option) any later version; incorporated herein by reference.
;
; ****************************************************************************
%ifndef IS_MDSLINUX
%define IS_SYSLINUX 1
%endif
%include "head.inc"
;
; Some semi-configurable constants... change on your own risk.
;
my_id equ syslinux_id
FILENAME_MAX_LG2 equ 6 ; log2(Max filename size Including final null)
FILENAME_MAX equ (1<<FILENAME_MAX_LG2) ; Max mangled filename size
NULLFILE equ 0 ; First char space == null filename
NULLOFFSET equ 0 ; Position in which to look
retry_count equ 16 ; How patient are we with the disk?
%assign HIGHMEM_SLOP 0 ; Avoid this much memory near the top
LDLINUX_MAGIC equ 0x3eb202fe ; A random number to identify ourselves with
MAX_OPEN_LG2 equ 6 ; log2(Max number of open files)
MAX_OPEN equ (1 << MAX_OPEN_LG2)
SECTOR_SHIFT equ 9
SECTOR_SIZE equ (1 << SECTOR_SHIFT)
;
; The following structure is used for "virtual kernels"; i.e. LILO-style
; option labels. The options we permit here are `kernel' and `append
; Since there is no room in the bottom 64K for all of these, we
; stick them in high memory and copy them down before we need them.
;
struc vkernel
vk_vname: resb FILENAME_MAX ; Virtual name **MUST BE FIRST!**
vk_rname: resb FILENAME_MAX ; Real name
vk_appendlen: resw 1
vk_type: resb 1 ; Type of file
alignb 4
vk_append: resb max_cmd_len+1 ; Command line
alignb 4
vk_end: equ $ ; Should be <= vk_size
endstruc
; ---------------------------------------------------------------------------
; BEGIN CODE
; ---------------------------------------------------------------------------
;
; Memory below this point is reserved for the BIOS and the MBR
;
section .earlybss
trackbufsize equ 8192
trackbuf resb trackbufsize ; Track buffer goes here
; ends at 2800h
section .bss16
alignb 16
global Files
Files resb MAX_OPEN*16 ; 16 == open_file_t_size
;
; Common bootstrap code for disk-based derivatives
;
%include "diskstart.inc"
;
; Now, everything is "up and running"... patch kaboom for more
; verbosity and using the full screen system
;
; E9 = JMP NEAR
mov di,kaboom.patch
mov al,0e9h
stosb
mov ax,kaboom2-2
sub ax,di
stosw
;
; Now we're all set to start with our *real* business. First load the
; configuration file (if any) and parse it.
;
; In previous versions I avoided using 32-bit registers because of a
; rumour some BIOSes clobbered the upper half of 32-bit registers at
; random. I figure, though, that if there are any of those still left
; they probably won't be trying to install Linux on them...
;
; The code is still ripe with 16-bitisms, though. Not worth the hassle
; to take'm out. In fact, we may want to put them back if we're going
; to boot ELKS at some point.
;
;
; Load configuration file
;
pm_call load_config
jz no_config_file
;
; Now we have the config file open. Parse the config file and
; run the user interface.
;
%include "ui.inc"
;
; close_dir:
; Deallocates a directory structure (pointer in SI)
; Assumes CS == DS.
;
close_dir:
and si,si
jz .closed
mov dword [si],0 ; First dword == file_sector
xor si,si
.closed: ret
;
;
; kaboom2: once everything is loaded, replace the part of kaboom
; starting with "kaboom.patch" with this part
kaboom2:
mov si,err_bootfailed
call writestr
cmp byte [kaboom.again+1],18h ; INT 18h version?
je .int18
call getchar
call vgaclearmode
int 19h ; And try once more to boot...
.norge: jmp short .norge ; If int 19h returned; this is the end
.int18:
call vgaclearmode
int 18h
.noreg: jmp short .noreg ; Nynorsk
;
; unmangle_name: Does the opposite of mangle_name; converts a DOS-mangled
; filename to the conventional representation. This is needed
; for the BOOT_IMAGE= parameter for the kernel.
; NOTE: A 13-byte buffer is mandatory, even if the string is
; known to be shorter.
;
; DS:SI -> input mangled file name
; ES:DI -> output buffer
;
; On return, DI points to the first byte after the output name,
; which is set to a null byte.
;
unmangle_name: call strcpy
dec di ; Point to final null byte
ret
; -----------------------------------------------------------------------------
; Common modules
; -----------------------------------------------------------------------------
%include "common.inc" ; Universal modules
%include "plaincon.inc" ; writechr
%include "writestr.inc" ; String output
%include "writehex.inc" ; Hexadecimal output
%include "localboot.inc" ; Disk-based local boot
; -----------------------------------------------------------------------------
; Begin data section
; -----------------------------------------------------------------------------
section .data16
copyright_str db ' Copyright (C) 1994-'
asciidec YEAR
db ' H. Peter Anvin et al', CR, LF, 0
err_bootfailed db CR, LF, 'Boot failed: please change disks and press '
db 'a key to continue.', CR, LF, 0
;
; Config file keyword table
;
%include "keywords.inc"
;
; Extensions to search for (in *forward* order).
;
exten_table: db '.cbt' ; COMBOOT (specific)
db '.bss' ; Boot Sector (add superblock)
db '.bs', 0 ; Boot Sector
db '.com' ; COMBOOT (same as DOS)
db '.c32' ; COM32
exten_table_end:
dd 0, 0 ; Need 8 null bytes here
;
; Misc initialized (data) variables
;
%ifdef debug ; This code for debugging only
debug_magic dw 0D00Dh ; Debug code sentinel
%endif
alignz 4
BufSafe dw trackbufsize/SECTOR_SIZE ; Clusters we can load into trackbuf
BufSafeBytes dw trackbufsize ; = how many bytes?
%ifndef DEPEND
%if ( trackbufsize % SECTOR_SIZE ) != 0
%error trackbufsize must be a multiple of SECTOR_SIZE
%endif
%endif
|
