In 2012 I was porting OpenEmbedded to target AArch64 so I can say that I did first OE builds for that architecture.
But today I did kind of reverse thing:
Build Configuration:
BB_VERSION = "1.21.1"
BUILD_SYS = "aarch64-linux"
NATIVELSBSTRING = "Fedora-21"
TARGET_SYS = "arm-oe-linux-gnueabi"
MACHINE = "genericarmv7a"
DISTRO = "nodistro"
DISTRO_VERSION = "nodistro.0"
TUNE_FEATURES = "armv7a vfp thumb neon callconvention-hard"
TARGET_FPU = "vfp-neon"
Yes — I did build on AArch64 machine targeting ARMv7a system. Had to edit one patch (pseudo-native was set to use very old glibc symbols which are not available on 64-bit ARM) but after that build was running just fine.
I did not tested resulting binaries.