[ipxe-devel] tftp booting a 32bit rhel 5 kernel/initrd (pxeboot images) and iPXE will just "reboot/crash"...

[Michael Brown]

On 29/07/15 09:53, Torgeir.Wulfsberg at kongsberg.com wrote:
> I recently noticed that iPXE as of the latest commit to this day (built
> on my rhel 6/7 client and Ubuntu 15), cannot boot a 32bit rhel 5 pxeboot
> kernel/initrd image (I have tested 5u3, 5u8, 5u11 images).
>
> iPXE will just "crash/reboot". Funnily enough my 32bit rhel 6 images
> works fine.
>
> Going back in time to the last good known state (I had downloaded in
> June 2014), then going back and forth (some months/commits) A LOT, I
> managed to locate where it would stop working, so I could reproduce this
> behavior.
>
> This is the commit it would crash/reboot (Makefile.housekeeping - "AR
> sort BLIB_OBJS"):
>
> https://git.ipxe.org/ipxe.git/commitdiff/335a7ddcd4e2d0faaee6d5b1edf0307dfba3d0e5

Thanks for the detailed bug report!  I have identified the root cause of 
the problem.  That vmlinuz image has both bzImage and ELFBoot headers, 
and so its detection by iPXE as bzImage or ELFBoot will depend on which 
order the objects happen to be linked in.

We can work around the problem by ensuring that bzImage detection gets 
tried first, which is just a case of changing the use of the various 
PROBE_XXX constants defined in include/ipxe/image.h.  Before I change 
that, I'd like to experiment a little further to find out why that image 
is failing to boot correctly when treated as ELFBoot.

Michael