add cross-compilation support to Makefile

Signed-off-by: Jan Noha <[email protected]>

Author: nohajc

Makefile

@@ -100,10 +100,18 @@ all: $(LIBRARY_RELEASE_$(OS)) libkrun.pc
 
 debug: $(LIBRARY_DEBUG_$(OS)) libkrun.pc
 
+ifeq ($(SYSROOT_LINUX),)
+# Build on Linux host
+CC_LINUX=$(CC)
+else
+# Cross-compile on macOS with the LLVM linker (brew install lld)
+CC_LINUX=clang -target aarch64-linux-gnu -fuse-ld=lld -Wl,-strip-debug --sysroot $(SYSROOT_LINUX) -Wno-c23-extensions
+endif
+
 ifeq ($(BUILD_INIT),1)
 INIT_BINARY = init/init
 $(INIT_BINARY): $(INIT_SRC)
-	$(CC) -O2 -static -Wall $(INIT_DEFS) -o $@ $(INIT_SRC) $(INIT_DEFS)
+	$(CC_LINUX) -O2 -static -Wall $(INIT_DEFS) -o $@ $(INIT_SRC) $(INIT_DEFS)
 endif
 
 $(LIBRARY_RELEASE_$(OS)): $(INIT_BINARY)