[syslinux] SYSLINUX 1.73-pre1

Michael K Ter Louw mterlouw at gmx.net
Tue Apr 23 23:07:39 PDT 2002


The module I test is Isolinux.  Version 1.73-pre1 works well for me.  I
only use it to boot my comboot program and to load memdisk to boot
floppy images, so I don't know how well it works when booting Linux
kernel images, etc.  There are however a couple issues that are still
around since 1.67:

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1) On systems where Isolinux fails to load properly, there is a small
bug that can cause the system to hang instead of rebooting when the user
hits a key.  This is the getchar bug; the function kaboom calls getchar
even though it's known at this point that getchar wasn't loaded into
memory properly.  It should be an easy fix, IMO.

2) If you try to boot any file that doesn't qualify as a linux kernel
(*.com, *.cbt, *.img, *.bss, *.bs) and that file is not in the ISOLINUX
directory (e.g. "boot: /files/floppy.img") it will fail to boot
properly.  This is because anything not in the ISOLINUX directory causes
Isolinux to "forget" the proper filename, and since it cannot read the
extension it defaults to booting the file as a Linux kernel.  There is a
simple, one instruction fix for this.  On line #3144 (under
searchdir_iso.resume), between the pop and mov instructions, add:

 "mov BYTE [di-1], '/'	; restore the slash in the filename".

*Notes: 
  - The line numbers given here are based on isolinux.asm version 1.72.
  - Examples of these fixes can be found in the archive located at:
http://freshmeat.net/redir/bootscriptor/28695/url_zip/Isolinux%20for%20B
oot%20Scriptor%20(1.72-1.0b).zip

----------------------------------------------------------------------

One change that would be helpful would be on line #2333, after the call
to vgaclearmode, would be to add one instruction:

"mov dl, [DriveNo]	; dl = booted drive number"

This isn't too big of a deal really, but passing the booted drive number
to the next loader in the boot process seems logical to me.  And it
makes one less thing I have to add to isolinux.asm as new releases are
made :)


I realize these changes aren't of a high priority, but they are quick,
tested fixes to known bugs/limitations and shouldn't be too much hassle
to implement.  As always Peter, thanks for all the great work you do :)
Isolinux is a great app, and vital to my program.


Mike








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