From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Mon, 3 Mar 2025 01:01:42 +0000 (-0800)
Subject: tools build: Fix fixdep dependencies
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a808a2b35f66658e6c49dc98b55a33fa1079fe72;p=thirdparty%2Flinux.git

tools build: Fix fixdep dependencies

The tools version of fixdep has broken dependencies.  It doesn't get
rebuilt if the host compiler or headers change.

Build fixdep with the tools kbuild infrastructure, so fixdep runs on
itself.  Due to the recursive dependency, its dependency file is
incomplete the very first time it gets built.  In that case build it a
second time to achieve fixdep inception.

Reported-by: Arthur Marsh <arthur.marsh@internode.on.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---

diff --git a/tools/build/Build b/tools/build/Build
new file mode 100644
index 0000000000000..1c7e598e9f593
--- /dev/null
+++ b/tools/build/Build
@@ -0,0 +1,2 @@
+hostprogs	:= fixdep
+fixdep-y	:= fixdep.o
diff --git a/tools/build/Makefile b/tools/build/Makefile
index 63ef218787616..a5b3c29b8d70c 100644
--- a/tools/build/Makefile
+++ b/tools/build/Makefile
@@ -37,5 +37,24 @@ ifneq ($(wildcard $(TMP_O)),)
 	$(Q)$(MAKE) -C feature OUTPUT=$(TMP_O) clean >/dev/null
 endif
 
-$(OUTPUT)fixdep: $(srctree)/tools/build/fixdep.c
-	$(QUIET_CC)$(HOSTCC) $(KBUILD_HOSTCFLAGS) $(KBUILD_HOSTLDFLAGS) -o $@ $<
+include $(srctree)/tools/build/Makefile.include
+
+FIXDEP		:= $(OUTPUT)fixdep
+FIXDEP_IN	:= $(OUTPUT)fixdep-in.o
+
+# To track fixdep's dependencies properly, fixdep needs to run on itself.
+# Build it twice the first time.
+$(FIXDEP_IN): FORCE
+	$(Q)if [ ! -f $(FIXDEP) ]; then						\
+		$(MAKE) $(build)=fixdep HOSTCFLAGS="$(KBUILD_HOSTCFLAGS)";	\
+		rm -f $(FIXDEP).o;						\
+	fi
+	$(Q)$(MAKE) $(build)=fixdep HOSTCFLAGS="$(KBUILD_HOSTCFLAGS)"
+
+
+$(FIXDEP): $(FIXDEP_IN)
+	$(QUIET_LINK)$(HOSTCC) $(FIXDEP_IN) $(KBUILD_HOSTLDFLAGS) -o $@
+
+FORCE:
+
+.PHONY: FORCE