Latest syslinux build breaks Rawhide images: any help figuring out why?

[Adam Williamson]

Hi, folks. We have a serious issue with Rawhide (F23) images at
present: syslinux is broken. This means all the images fail to boot
when syslinux is used as the bootloader (they do boot when grub is
used, i.e. when booting via UEFI).

https://bugzilla.redhat.com/show_bug.cgi?id=1234653

this started happening when the F23 rebuild of syslinux landed - 6.03
-4.fc23. Prior to that, the attempt to rebuild it for the hardening
change - which would have been 6.03-4.fc23 - failed, so the previous
build was 6.02-2.fc22 , the same build that shipped in F22.

If you build 6.03-4 for F21 and sub that into an image, it boots fine,
so the issue is clearly something in the F23 compilation environment,
but I have not yet been able to see what. The obvious candidate is the
hardening stuff itself, but in fact - so far as I can see - none of the
relevant flags is actually different between F21 and F23, it looks like
the build was already 'hardened'. So it may instead be some change of
behaviour in GCC or similar.

It's worth noting that trying to build 6.03-4 for F22 fails entirely:

http://koji.fedoraproject.org/koji/taskinfo?taskID=10184690

If anyone wants to see the logs from the F21 and F23 builds, my scratch
builds are here:

21 - http://koji.fedoraproject.org/koji/taskinfo?taskID=10183978
23 - http://koji.fedoraproject.org/koji/taskinfo?taskID=10183680

and you can find nightly live images at https://koji.fedoraproject.org/
koji/tasks?owner=masher&state=closed&view=flat&method=createLiveCD&orde
r=-id - any current Rawhide live will fail to boot on x86 BIOS systems
due to this problem.

Any help in figuring out the problem would be appreciated! Thanks.
-- 
Adam Williamson
Fedora QA Community Monkey
IRC: adamw | Twitter: AdamW_Fedora | XMPP: adamw AT happyassassin . net
http://www.happyassassin.net