Comment 30 for bug 1341944

Sorry, the command needs to be without "-p /EFI/BOOT" (that only applies if the grub.cfg is there instead of in /boot/grub).
grub-mkimage -o bootia32.efi -O i386-efi ntfs hfs appleldr boot cat efi_gop efi_uga elf fat hfsplus iso9660 linux keylayouts memdisk minicmd part_apple ext2 extcmd xfs xnu part_bsd part_gpt search search_fs_file chain btrfs loadbios loadenv lvm minix minix2 reiserfs memrw mmap msdospart scsi loopback normal configfile gzio all_video efi_gop efi_uga gfxterm gettext echo boot chain eval ls test sleep png gfxmenu