Well, with this simple patch I'm able to load initrd from a different
disk. It's not finished, it's just to ask you if I'm going in the
right
direction...
I have also some suggestion/question:
- many boot sector I saw use [bp+xx] addressing to gain some bytes. Why
don't you use such method?
- had syslinux been tested with usb floppy? You test dl however using
usb floppy dl == 0x80
- in debugentrypt you use sometimes [Z+...] and sometimes not (see
[Z+DataArea] and [DataArea]) ..
- old bios specification state that you should reset disk and retry 3
times but you don't perhaps for size problems however you should do so
to load others parts (kernel and others big stuff)
- you load entire FAT but on large disks (FAT16) you load 128K instead
of some sectors (I don't think kernel/initrd get so defragged). It's not
better to use a simple cache?
What's the best method to make patch for syslinux? Just use usually
patch and send them to you?
freddy77
Patch:
--- syslinux-2.08.orig/ldlinux.asm 2003-12-04 04:47:57.000000000
+0100
+++ syslinux-2.08/ldlinux.asm 2003-12-18 23:21:48.000000000 +0100
@@ -694,25 +694,33 @@
; on.
;
jmp 0:.next
.next:
;
; Tell the user we got this far
;
mov si,syslinux_banner
call writestr
+; begin - freddy77
+ call load_fat
+ jmp load_fat_next
+; end - freddy77
;
; Remember, the boot sector loaded only the first cluster of
LDLINUX.SYS. ; We can really only rely on a single sector having been
loaded. Hence ; we should load the FAT into RAM and start chasing
pointers... ;
+; begin - freddy77
+
+load_fat:
+; end - freddy77
xor ax,ax
cwd
inc dx ; DX:AX <- 64K
div word [bxBytesPerSec] ; sectors/64K
mov si,ax
push es
mov bx,fat_seg ; Load into fat_seg:0000
mov es,bx
@@ -730,20 +738,25 @@
call getlinsecsr
sub cx,bp
jz fat_load_done ; Last moby?
add eax,ebp ; Advance sector count
mov bx,es ; Next 64K moby
add bx,1000h
mov es,bx
jmp short fat_load_loop
fat_load_done:
pop es
+; begin - freddy77
+ ret
+
+load_fat_next:
+; end - freddy77
;
; Fine, now we have the FAT in memory. How big is a cluster, really?
; Also figure out how many clusters will fit in an 8K buffer, and how
; many sectors and bytes that is ;
mov edi,[bxBytesPerSec] ; Used a lot below
mov eax,[SecPerClust]
mov si,ax ; Also used a lot
mul di
mov [ClustSize],eax ; Bytes/cluster
@@ -1436,20 +1449,27 @@
%ifdef debug ; This code for debugging only
debug_magic dw 0D00Dh ; Debug code sentinel
%endif
AppendLen dw 0 ; Bytes in append= command
OntimeoutLen dw 0 ; Bytes in ontimeout command
OnerrorLen dw 0 ; Bytes in onerror command
KbdTimeOut dw 0 ; Keyboard timeout (if any)
CmdLinePtr dw cmd_line_here ; Command line advancing pointer
initrd_flag equ $
initrd_ptr dw 0 ; Initial ramdisk pointer/flag
+; begin - freddy77
+
+change_disk_msg db 'Insert disk #'
+initrd_span db 0
+ db ' and press a key', CR, LF, 0
+
+; end - freddy77
VKernelCtr dw 0 ; Number of registered vkernels
ForcePrompt dw 0 ; Force prompt
AllowImplicit dw 1 ; Allow implicit kernels
SerialPort dw 0 ; Serial port base (or 0 for no
serial port)
VGAFontSize dw 16 ; Defaults to 16 byte font
UserFont db 0 ; Using a user-specified font
ScrollAttribute db 07h ; White on black (for
text mode)
;
; Stuff for the command line; we do some trickery here with equ to
avoid ; tons of zeros appended to our file and wasting space
--- syslinux-2.08.orig/runkernel.inc 2003-08-22 05:39:37.000000000
+0200
+++ syslinux-2.08/runkernel.inc 2003-12-18 23:16:18.000000000 +0100
@@ -156,20 +156,32 @@
.notkeep:
%endif
push es ; Save ES ->
real_mode_seg
push cs
pop es ; Set ES <- normal DS
mov di,initrd_cmd
mov cx,initrd_cmd_len
repe cmpsb
jne not_initrd
+; begin - freddy77
+ ; detect change needed
+ lodsw
+ cmp ah, ':'
+ je set_initrd_span
+ xor ax,ax
+ dec si
+ dec si
+set_initrd_span:
+ mov [es:initrd_span], al
+; end - freddy77
+
mov di,InitRD
push si ; mangle_dir mangles si
call mangle_name ; Mangle ramdisk name
pop si
cmp byte [es:InitRD],NULLFILE ; Null filename?
seta byte [es:initrd_flag] ; Set flag if not
not_initrd: pop es ; Restore ES ->
real_mode_seg
skip_this_opt: lodsb ; Load from command
line
cmp al,' '
ja skip_this_opt
@@ -287,20 +299,28 @@
call cwritestr
;
; Now see if we have an initial RAMdisk; if so, do requisite
computation ; We know we have a new kernel; the old_kernel code already
will have objected ; if we tried to load initrd using an old kernel ;
load_initrd:
test byte [initrd_flag],1
jz nk_noinitrd
+; begin - freddy77
+ ; detect change needed
+ cmp byte [initrd_span], 0
+ je no_change_disk
+retry_disk:
+ call change_disk
+no_change_disk:
+; end - freddy77
push es ; ES->real_mode_seg
push ds
pop es ; We need ES==DS
mov si,InitRD
mov di,InitRDCName
call unmangle_name ; Create human-readable
name
sub di,InitRDCName
mov [InitRDCNameLen],di
mov di,InitRD
call searchdir ; Look for it in
directory
@@ -322,25 +342,39 @@
mov [es:su_ramdiskat],edx ; Load address
call loadinitrd ; Load initial ramdisk
jmp short initrd_end
initrd_notthere:
mov si,err_noinitrd
call cwritestr
mov si,InitRDCName
call cwritestr
mov si,crlf_msg
+; begin - freddy77
+ cmp byte [initrd_span], 0
+ jne retry_disk
+; end - freddy77
jmp abort_load
no_high_mem: mov si,err_nohighmem ; Error routine
jmp abort_load
+; begin - freddy77
+change_disk:
+ mov si, change_disk_msg
+ call cwritestr
+ xor ax, ax
+ int 16h
+ call load_fat
+ ret
+; end - freddy77
+
initrd_end:
nk_noinitrd:
;
; Abandon hope, ye that enter here! We do no longer permit aborts. ;
call abort_check ; Last chance!!
mov si,ready_msg
call cwritestr
