Make: Detect arm-embedded architecture cross compilation target

test/mk/compiler.mk has logic for detecting the target architecture,
taking into account both the host architecture and, if present, the
cross prefix.

Previously, cross-compilation for embedded Arm targets was not
recognized, and the host architecture (e.g. AArch64 or x86_64)
chosen as the target architecture. This would lead to compilation
failures because the makefiles would later set MLK_FORCE_XXX based
on the arch, contradicting the actual target of the (cross)-compilation.

This commit fixes the issue by betecting arm embedded cross
compilation targets.

This commit also modifies the Makefiles to not fall back to the
host architecture as the target architecture if a cross prefix
is set but not recognized.

Signed-off-by: Hanno Becker <[email protected]>

Author: hanno-becker

test/mk/compiler.mk

@@ -13,14 +13,15 @@
 ifndef _COMPILER_MK
 _COMPILER_MK :=
 
-# Normalize architecture names
+
+# Override ARCH for cross-compilation based on CROSS_PREFIX
+ifeq ($(CROSS_PREFIX),)
 ARCH := $(shell uname -m)
+# Normalize architecture names
 ifeq ($(ARCH),arm64)
 ARCH := aarch64
 endif
-
-# Override ARCH for cross-compilation based on CROSS_PREFIX
-ifneq ($(CROSS_PREFIX),)
+else # CROSS_PREFIX
 ifneq ($(findstring x86_64, $(CROSS_PREFIX)),)
 ARCH := x86_64
 else ifneq ($(findstring aarch64_be, $(CROSS_PREFIX)),)
@@ -33,6 +34,10 @@ else ifneq ($(findstring riscv32, $(CROSS_PREFIX)),)
 ARCH := riscv32
 else ifneq ($(findstring powerpc64le, $(CROSS_PREFIX)),)
 ARCH := powerpc64le
+else ifneq ($(findstring arm-none-eabi-, $(CROSS_PREFIX)),)
+ARCH := arm
+else
+ARCH := unknown
 endif
 endif # CROSS_PREFIX