meta-arm/meta-arm-toolchain/recipes-devtools/gcc/gcc-arm-common.inc

# gcc-target.inc in OE-Core has these 2 lines in do_install():
#
# | # Add unwind.h, it comes from libgcc which we don't want to build again
# | install ${STAGING_LIBDIR_NATIVE}/${TARGET_SYS}/gcc/${TARGET_SYS}/${BINV}/include/unwind.h ${D}${libdir}/gcc/${TARGET_SYS}/${BINV}/include/
#
# When TCMODE="external-arm" libgcc is provided by external-arm-toolchain.bb
# And while it stages the necessary unwind.h file, it ends up in slightly
# different location. While this is a kludge, be very conservative - only
# copy the file for target build in recipe-specific sysroot, in external-arm
# toolchain mode and if the required file does not exist already.

do_install:prepend:class-target () {
	if [ "${TCMODE}" = "external-arm" -a ! -f ${STAGING_LIBDIR_NATIVE}/${TARGET_SYS}/gcc/${TARGET_SYS}/${BINV}/include/unwind.h ]; then
		install -d ${STAGING_LIBDIR_NATIVE}/${TARGET_SYS}/gcc/${TARGET_SYS}/${BINV}/include/
		install ${EXTERNAL_TOOLCHAIN}/lib/gcc/${EAT_TARGET_SYS}/${EAT_VER_GCC}/include/unwind.h ${STAGING_LIBDIR_NATIVE}/${TARGET_SYS}/gcc/${TARGET_SYS}/${BINV}/include/
	fi
}

# When TCMODE="external-arm" and TARGET_SYS is different from EAT_TARGET_SYS,
# gcc installs additional aliases as ${TARGET_SYS}-${EAT_TARGET_SYS}-gcc, etc.
# Since those are not packaged and not too useful, let's remove them to avoid
# QA issues
do_install:append () {
	for f in g++ gcc gcc-ar gcc-ranlib gcc-nm; do
		rm -f ${D}${bindir}/${TARGET_SYS}-${EAT_TARGET_SYS}-$f
	done
}