[syslinux] isolinux problem since 3.74

[Stillwell, Bryan]

I'm working on getting the latest Linux distros working well on one of
our prototype machines, however, some of them are failing to boot into
the installer from the CD/DVD images.  I've narrowed it down to isolinux
hanging just before displaying the graphical menu.  After a little
bisecting between the last version that worked (3.73) and the first
version which was broken (3.74), I found this piece of code that is
responsible for the problem:

======================================================================
--- syslinux-3.73/core/com32.inc        2009-10-12 16:51:06.294747337
-0600
+++ syslinux-3.74/core/com32.inc        2009-10-12 16:51:09.750744468
-0600
@@ -172,13 +172,14 @@

                ; Now everything is set up for interrupts...

+               push dword [HighMemSize]        ; Memory managed by
Syslinux
                push dword com32_cfarcall       ; Cfarcall entry point
                push dword com32_farcall        ; Farcall entry point
                push dword (1 << 16)            ; 64K bounce buffer
                push dword (comboot_seg << 4)   ; Bounce buffer address
                push dword com32_intcall        ; Intcall entry point
                push dword command_line         ; Command line pointer
-               push dword 6                    ; Argument count
+               push dword 7                    ; Argument count
                sti                             ; Interrupts OK now
                call pm_entry                   ; Run the program...
                ; ... on return, fall through to com32_exit ...
======================================================================

Removing these changes in the 3.83 release allows the prototype machines
to boot the installer, but I'm not sure why these changes are needed
since it works on other (released) machines I have access to.  I'm
writing the list because I would like to determine if this is a firmware
bug that we can fix before we release, or a bug in isolinux that this
machine aggrevates?

Thanks,
Bryan