Can't boot efi image (iso or vmdk) in virtualbox

Hello,

I can't boot oe-core's efi image in virtualbox (with UEFI set), the image works well on real EFI hardware, but there is nothing output in virtual box after grub loaded, after set debug=all in grub command, it hangs at:
[a lot of such lines]
mmap/efi/mmap.c:66: EFI memory region 0xfoo-foo: n
[a lot of such lines]

My local.conf: (krogoth branch)
MACHINE = "qemux86-64"
IMAGE_FSTYPES += "iso hddimg vmdk qcow2"
MACHINE_FEATURES_remove = "pcbios"
MACHINE_FEATURES_append = " efi"

I tried virtual box(with EFI set) + Fedora23, it works well.

virtualbox version:
5.0.14 (ubuntu 15.04's version)
And
5.0.18

Does anyone has met the similar issue, please ? Any suggestion is appreciated.

Thanks

Robert