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 d92cc4d51643 ("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 <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

1 files changed, 2 insertions, 15 deletions

diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst
index db3af0b45baf..b008b90b92c9 100644
--- a/Documentation/kbuild/makefiles.rst
+++ b/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".