All built targets need fixdep to be built first, before handling object
dependencies [1]. We're missing one such dependency before the libsubcmd
target.

This resolves .cmd file generation issues such that the following
sequence produces many fewer results:

  $ git clean -xfd tools/
  $ make tools/objtool
  $ grep "cannot find fixdep" $(find tools/objtool -name '*.cmd')

In particular, only a buggy tools/objtool/libsubcmd/.fixdep.o.cmd
remains, due to circular dependencies of fixdep on itself.

Such incomplete .cmd files don't usually cause a direct problem, since
they're designed to fail "open", but they can cause some subtle problems
that would otherwise be handled by proper fixdep'd dependency files.

[1] This problem is better described in commit abb26210a395 ("perf
tools: Force fixdep compilation at the start of the build"). I don't
apply its solution here, because additional recursive make can be a bit
of overkill.

Link: https://lore.kernel.org/all/ZGVi9HbI43R5trN8@bhelgaas/
Link: https://lore.kernel.org/all/Zk-C5Eg84yt6_nml@google.com/
Signed-off-by: Brian Norris <briannorris@chromium.org>
---

(no changes since v1)

 tools/lib/subcmd/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/subcmd/Makefile b/tools/lib/subcmd/Makefile
index b87213263a5e..59b09f280e49 100644
--- a/tools/lib/subcmd/Makefile
+++ b/tools/lib/subcmd/Makefile
@@ -76,7 +76,7 @@ include $(srctree)/tools/build/Makefile.include
 
 all: fixdep $(LIBFILE)
 
-$(SUBCMD_IN): FORCE
+$(SUBCMD_IN): fixdep FORCE
 	@$(MAKE) $(build)=libsubcmd
 
 $(LIBFILE): $(SUBCMD_IN)
-- 
2.45.2.803.g4e1b14247a-goog

On Tue, Jul 02, 2024 at 02:58:37PM -0700, Brian Norris wrote:
> All built targets need fixdep to be built first, before handling object
> dependencies [1]. We're missing one such dependency before the libsubcmd
> target.
> 
> This resolves .cmd file generation issues such that the following
> sequence produces many fewer results:
> 
>   $ git clean -xfd tools/
>   $ make tools/objtool
>   $ grep "cannot find fixdep" $(find tools/objtool -name '*.cmd')
> 
> In particular, only a buggy tools/objtool/libsubcmd/.fixdep.o.cmd
> remains, due to circular dependencies of fixdep on itself.
> 
> Such incomplete .cmd files don't usually cause a direct problem, since
> they're designed to fail "open", but they can cause some subtle problems
> that would otherwise be handled by proper fixdep'd dependency files.
> 
> [1] This problem is better described in commit abb26210a395 ("perf
> tools: Force fixdep compilation at the start of the build"). I don't
> apply its solution here, because additional recursive make can be a bit
> of overkill.
> 
> Link: https://lore.kernel.org/all/ZGVi9HbI43R5trN8@bhelgaas/
> Link: https://lore.kernel.org/all/Zk-C5Eg84yt6_nml@google.com/
> Signed-off-by: Brian Norris <briannorris@chromium.org>

Acked-by: Jiri Olsa <jolsa@kernel.org>

jirka

> ---
> 
> (no changes since v1)
> 
>  tools/lib/subcmd/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/lib/subcmd/Makefile b/tools/lib/subcmd/Makefile
> index b87213263a5e..59b09f280e49 100644
> --- a/tools/lib/subcmd/Makefile
> +++ b/tools/lib/subcmd/Makefile
> @@ -76,7 +76,7 @@ include $(srctree)/tools/build/Makefile.include
>  
>  all: fixdep $(LIBFILE)
>  
> -$(SUBCMD_IN): FORCE
> +$(SUBCMD_IN): fixdep FORCE
>  	@$(MAKE) $(build)=libsubcmd
>  
>  $(LIBFILE): $(SUBCMD_IN)
> -- 
> 2.45.2.803.g4e1b14247a-goog
> 
>