kbuild: use more subdir- for visiting subdirectories while cleaning

Documentation/kbuild/makefiles.rst suggests to use "archclean" for
cleaning arch/$(SRCARCH)/boot/, but it is not a hard requirement.

Since commit d92cc4d ("kbuild: require all architectures to have
arch/$(SRCARCH)/Kbuild"), we can use the "subdir- += boot" trick for
all architectures. This can take advantage of the parallel option (-j)
for "make clean".

I also cleaned up the comments in arch/$(SRCARCH)/Makefile. The "archdep"
target no longer exists.

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
Acked-by: Michael Ellerman <[email protected]> (powerpc)

Author: masahir0y

Documentation/kbuild/makefiles.rst

@@ -1050,22 +1050,9 @@ is not sufficient this sometimes needs to be explicit.
 The above assignment instructs kbuild to descend down in the
 directory compressed/ when "make clean" is executed.
 
-To support the clean infrastructure in the Makefiles that build the
-final bootimage there is an optional target named archclean:
-
-	Example::
-
-		#arch/x86/Makefile
-		archclean:
-			$(Q)$(MAKE) $(clean)=arch/x86/boot
-
-When "make clean" is executed, make will descend down in arch/x86/boot,
-and clean as usual. The Makefile located in arch/x86/boot/ may use
-the subdir- trick to descend further down.
-
 Note 1: arch/$(SRCARCH)/Makefile cannot use "subdir-", because that file is
-included in the top level makefile, and the kbuild infrastructure
-is not operational at that point.
+included in the top level makefile. Instead, arch/$(SRCARCH)/Kbuild can use
+"subdir-".
 
 Note 2: All directories listed in core-y, libs-y, drivers-y and net-y will
 be visited during "make clean".

arch/alpha/Kbuild

@@ -1,3 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-y			+= kernel/ mm/
 obj-$(CONFIG_MATHEMU)	+= math-emu/
+
+# for cleaning
+subdir- += boot

arch/alpha/Makefile

@@ -55,9 +55,6 @@ $(boot)/vmlinux.gz: vmlinux
 bootimage bootpfile bootpzfile: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
 
-archclean:
-	$(Q)$(MAKE) $(clean)=$(boot)
-
 archheaders:
 	$(Q)$(MAKE) $(build)=arch/alpha/kernel/syscalls all
 

arch/arc/Kbuild

@@ -1,3 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-y += kernel/
 obj-y += mm/
+
+# for cleaning
+subdir- += boot

arch/arc/Makefile

@@ -112,6 +112,3 @@ uImage: $(uimage-default-y)
 	@$(kecho) '  Image $(boot)/uImage is ready'
 
 CLEAN_FILES += $(boot)/uImage
-
-archclean:
-	$(Q)$(MAKE) $(clean)=$(boot)

arch/arm/Kbuild

@@ -9,3 +9,6 @@ obj-y				+= kernel/ mm/ common/
 obj-y				+= probes/
 obj-y				+= net/
 obj-y				+= crypto/
+
+# for cleaning
+subdir- += boot

arch/arm/Makefile

@@ -317,10 +317,6 @@ ifeq ($(CONFIG_VDSO),y)
 	$(Q)$(MAKE) $(build)=arch/arm/vdso $@
 endif
 
-# We use MRPROPER_FILES and CLEAN_FILES now
-archclean:
-	$(Q)$(MAKE) $(clean)=$(boot)
-
 # My testing targets (bypasses dependencies)
 bp:;	$(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/bootpImage
 

arch/arm64/Kbuild

@@ -4,3 +4,6 @@ obj-$(CONFIG_KVM)	+= kvm/
 obj-$(CONFIG_XEN)	+= xen/
 obj-$(subst m,y,$(CONFIG_HYPERV))	+= hyperv/
 obj-$(CONFIG_CRYPTO)	+= crypto/
+
+# for cleaning
+subdir- += boot

arch/arm64/Makefile

@@ -182,13 +182,6 @@ ifeq ($(CONFIG_ARM64_USE_LSE_ATOMICS),y)
   endif
 endif
 
-
-# We use MRPROPER_FILES and CLEAN_FILES now
-archclean:
-	$(Q)$(MAKE) $(clean)=$(boot)
-	$(Q)$(MAKE) $(clean)=arch/arm64/kernel/vdso
-	$(Q)$(MAKE) $(clean)=arch/arm64/kernel/vdso32
-
 ifeq ($(KBUILD_EXTMOD),)
 # We need to generate vdso-offsets.h before compiling certain files in kernel/.
 # In order to do that, we should use the archprepare target, but we can't since

arch/arm64/kernel/Makefile

@@ -81,3 +81,6 @@ extra-y					+= $(head-y) vmlinux.lds
 ifeq ($(CONFIG_DEBUG_EFI),y)
 AFLAGS_head.o += -DVMLINUX_PATH="\"$(realpath $(objtree)/vmlinux)\""
 endif
+
+# for cleaning
+subdir- += vdso vdso32