[syslinux] "EDD Load error" on btrfs, how to debug?

[Anatol Pomozov]

Hi

I have a computer with BIOS and Linux Arch installed.

Starting from a recent syslinux update (6.02->6.03pre9) I am not able
to use syslinux anymore. I try to boot my computer and the only thing
I see is "EDD Load error - Boot error" message. When I install 6.02
back the system is completely fine.

Other people use syslinux 6.03 fine. They use ext4 and I use btrfs as
my root partition fs so it might be a problem for syslinux.

I would like to debug and see this problem fixed. How to enable more
verbose output at boot stage? I would like to get more information
about why the EDD error happens. Any other debugging advises?