Re: [PATCH v2 05/13] kbuild: detect objtool update without using .SECONDEXPANSION

On Tue, Aug 31, 2021 at 04:39:56PM +0900, Masahiro Yamada wrote:

Redo commit 8852c5524029 ("kbuild: Fix objtool dependency for
'OBJECT_FILES_NON_STANDARD_<obj> := n'") to add the objtool
dependency in a cleaner way.

Using .SECONDEXPANSION ends up with unreadable code due to escaped
dollars. Also, it is not efficient because the second half of
Makefile.build is parsed twice every time.

Append the objtool dependency to the *.cmd files at the build time.

This is what fixdep and gen_ksymdeps.sh already do. So, following the
same pattern seems a natural solution.

This allows us to drop $$(objtool_deps) entirely.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Okay, so IIUC, this means objtool (and args) now ends up in the .cmd
file instead of in the Makefile dep rules? That seems reasonable.

Reviewed-by: Kees Cook <redacted>

-- 
Kees Cook