[syslinux] corner cases in 308-pre5, pxelinux.cfg/default, esp w simple menus

[H. Peter Anvin]

Jim Cromie wrote:
> 
> the following config-file triggers a couple of odd corner-cases in 
> 3.08-pre5 ;
> 
> SERIAL    0 19200
> CONSOLE 0
> 
> APPEND     console=ttyS0,19200n81 root=/dev/hda1
> IMPLICIT 0
> 
> #DEFAULT        sk1
> #DEFAULT        menu.c32

A syslinux comment is # followed by whitespace.  #DEFAULT is not a valid 
comment; # DEFAULT is, however; see your a.1 note.

The complaint, of course, is that it can't figure out what you meant 
with the unknown directive #DEFAULT.

>    a.  I get a complaint about an illegal command in the file -
>          if remove the commented line(s), that complaint goes away.
> 
> CLIENT MAC ADDR: 00 00 24 C2 46 C8
> CLIENT IP: 192.168.42.100  MASK: 255.255.255.0  DHCP IP: 192.168.42.1
> 6-c8-00-24-c2-4
> PXELINUX 3.08 0x41effbca  Copyright (C) 1994-2005 H. Peter Anvin
> Unknown keyword in config file.
> Unknown keyword in config file.
> Could not find kernel image: menu.c32

The problem is that you have IMPLICIT 0, but menu.c32 is, actually, an 
implicit invocation.

The workaround is to instead do this:

IMPLICIT 0
DEFAULT menu
LABEL menu
	KERNEL menu.c32
	MENU HIDE

It's ugly, I agree.  I'll have to think about that.

	-hpa