Add OpenMP support for custom external toolchains

index 08a79ee4d9..74e445d625 100644
@@ -421,6 +421,14 @@ config BR2_TOOLCHAIN_EXTERNAL_FORTRAN
 	  support. If you don't know, leave the default value,
 	  Buildroot will tell you if it's correct or not.
 
+config BR2_TOOLCHAIN_EXTERNAL_OPENMP
+	bool "Toolchain has OpenMP support?"
+	select BR2_TOOLCHAIN_HAS_OPENMP
+	help
+	  Select this option if your external toolchain has OpenMP
+	  support. If you don't know, leave the default value,
+	  Buildroot will tell you if it's correct or not.
+
 config BR2_TOOLCHAIN_EXTRA_EXTERNAL_LIBS
 	string "Extra toolchain libraries to be copied to target"
 	help

index e5520c00c3..03355f56dd 100644
@@ -359,6 +359,24 @@ check_fortran = \
 	fi ; \
 	rm -f $${__o}* \
 
+#
+#
+# Check that the external toolchain supports OpenMP
+#
+# $1: cross-gcc path
+#
+check_openmp = \
+	__CROSS_CC=$(strip $1) ; \
+	__o=$(BUILD_DIR)/.br-toolchain-test-openmp.tmp ; \
+	printf '\#include <omp.h>\nint main(void) { return omp_get_thread_num(); }' | \
+	$${__CROSS_CC} -fopenmp -x c -o $${__o} - ; \
+	if test $$? -ne 0 ; then \
+		rm -f $${__o}* ; \
+		echo "OpenMP support is selected but is not available in external toolchain"; \
+		exit 1 ; \
+	fi ; \
+	rm -f $${__o}* \
+
 #
 # Check that the cross-compiler given in the configuration exists
 #

index 747837fdc6..baf719ad1f 100644
@@ -545,6 +545,9 @@ define $(2)_CONFIGURE_CMDS
 	if test "$$(BR2_TOOLCHAIN_HAS_FORTRAN)" = "y" ; then \
 		$$(call check_fortran,$$(TOOLCHAIN_EXTERNAL_FC)) ; \
 	fi ; \
+	if test "$$(BR2_TOOLCHAIN_HAS_OPENMP)" = "y" ; then \
+		$$(call check_openmp,$$(TOOLCHAIN_EXTERNAL_CC)) ; \
+	fi ; \
 	if test "$$(BR2_TOOLCHAIN_EXTERNAL_UCLIBC)" = "y" ; then \
 		$$(call check_uclibc,$$$${SYSROOT_DIR}) ; \
 	elif test "$$(BR2_TOOLCHAIN_EXTERNAL_MUSL)" = "y" ; then \