As of June 2017 still not possible to boot from XFS. Maybe Syslinux 6.04 Changelog http://www.syslinux.org/wiki/index.php?title=Syslinux_6_Changelog :
"XFS: Support XFS on-disk V5, node directories version 3, xfsprogs 4.x. (Paulo Alcantara)."
As of June 2017 still not possible to boot from XFS. Maybe Syslinux 6.04 Changelog http://www.syslinux.org/wiki/index.php?title=Syslinux_6_Changelog :
"XFS: Support XFS on-disk V5, node directories version 3, xfsprogs 4.x. (Paulo Alcantara)."