[syslinux] possible ext4 handling bug in syslinux 6.03

[R Stachowiak]

Hi,

I've spent few long hours on weekend trying to get syslinux as boot
loader for my alpine linux.

Long story short: Failing to load ldlinux.c32 on ext4, but after
changing file system from ext4 to ext3, everything worked (all other
things being the same).

Details below, my setup is fairly complicated so this is might be a
partial reason, ALTHOUGH final and the only change which makes thing
work was reformatting ext4 to ext3.

* error message: Failed to load ldlinux.c32, so MBR works, so I guess
ldlinux.sys is probably loaded and then error happens
* platform, intel skylake, x64
* one disk (SSD M.2)
* five partitions over GPT on this disk
* hybrid/protective (fake) MBR with 4 partitions defined
* linux on last partition (fifth in GPT, fourth in protective MBR),
formated either ext4( not working), or ext3 (working)
* no separate boot partiton (everything including syslinux in one
partition (the last one on the disk))
* proper MBR with mbr.bin from syslinux 6.03
* syslinux installed with extlinux --install /boot  (while booted from
livecd and chrooted into final linux)
* upon installation, partition is correctly being recognized as
/dev/sda5, so syslinux is using GPT here, and boot record of this
partition is properly changed
* linux starts from under virtualbox - yeah I know it is complicated
story :) - in BIOS mode (not EFI), hence using MBR information
* I'm using newest alpine linux on intel x64 as a guest to be booted.

I'm willing to help to debug this problem further.

rdslw