Some cross compilers may not just be prefixed with ARCH, customize them
by architecture may simplify the test a lot, especially, when iterate
with ARCH.

After customizing this for every architecture, the minimal test argument
will be architecture itself, no CROSS_COMPILE required to be passed.

If the prefix of installed cross compiler is not the same as the one
customized, we can also pass CROSS_COMPILE as before or even pass
CROSS_COMPILE_<ARCH>.

Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
---
 tools/testing/selftests/nolibc/Makefile | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
index 3a61fa7e42a0..3f15c7f7ef76 100644
--- a/tools/testing/selftests/nolibc/Makefile
+++ b/tools/testing/selftests/nolibc/Makefile
@@ -45,6 +45,12 @@ IMAGE_loongarch  = arch/loongarch/boot/vmlinuz.efi
 IMAGE            = $(IMAGE_$(XARCH))
 IMAGE_NAME       = $(notdir $(IMAGE))
 
+# CROSS_COMPILE: cross toolchain prefix by architecture
+CROSS_COMPILE           ?= $(CROSS_COMPILE_$(XARCH))
+
+# make sure CC is prefixed with CROSS_COMPILE
+$(call allow-override,CC,$(CROSS_COMPILE)gcc)
+
 # default kernel configurations that appear to be usable
 DEFCONFIG_i386       = defconfig
 DEFCONFIG_x86_64     = defconfig
-- 
2.25.1