[syslinux] Boot iPXE from syslinux/isolinux

[H. Peter Anvin]

On 10/24/2013 01:09 AM, Christian Hesse wrote:
>>> 
>>> version 6.02-pre5 works, 6.02-pre6 does not.
>> 
>> Struggled with git bisect, but finally succeeded:
>> 
>> 8f470e7bfe75f6401f6c5432988c620b863ad274 is the first bad commit 
>> commit 8f470e7bfe75f6401f6c5432988c620b863ad274 Author: Matt
>> Fleming <matt.fleming at intel.com> Date:   Tue Jul 16 15:15:54 2013
>> +0100
>> 
>> movebits: Add syslinux_memmap_find()
>> 
>> Refactor the code for finding a suitable location for kernel 
>> protected-mode and real-mode data. It's complicated enough that
>> it deserves to be separated into its own function.
>> 
>> Signed-off-by: Matt Fleming <matt.fleming at intel.com>
>> 
>> :040000 040000 a7f3dc3f6ac34bd09336eff39e2f3d2d1bd8c9b6 
>> 3e4cbdfc3cb9928c5c809fc4400623eefbc398f4 M      com32
> 
> If anybody tries to reproduce: I have uploaded an iPXE zImage that
> isolinux fails to boot: http://www.eworm.de/tmp/ipxe.lkrn
> 
> Let be know if you need any more info.
> 

So this looks to be a zImage file (as opposed to a bzImage file), but
it does have a substantial payload (0x59f50 bytes.)

I am guessing that that is the source of the problems, but I'm still
at a loss from staring at the code.  If you could try turning on
debugging output by having debug.c32 installed on the system and running:

debug bios_boot_linux calc_cmdline_offset

... from the command line before trying to load ipxe.lkrn?

I should try it out myself if I can find the time...

	-hpa