Re: [PATCH 3/5] tools lib subcmd: Add dependency test to install_headers

From: Nicolas Schier <nicolas@fjasle.eu>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Tom Rix <trix@redhat.com>, Masahiro Yamada <masahiroy@kernel.org>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	bpf@vger.kernel.org, llvm@lists.linux.dev,
	Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH 3/5] tools lib subcmd: Add dependency test to install_headers
Date: Mon, 12 Dec 2022 21:57:38 +0100	[thread overview]
Message-ID: <Y5eVwlId2A2/pN40@fjasle.eu> (raw)
In-Reply-To: <20221202045743.2639466-4-irogers@google.com>

On Thu, Dec 01, 2022 at 08:57:41PM -0800 Ian Rogers wrote:
> Compute the headers to be installed from their source headers and make
> each have its own build target to install it. Using dependencies
> avoids headers being reinstalled and getting a new timestamp which
> then causes files that depend on the header to be rebuilt.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/lib/subcmd/Makefile | 23 +++++++++++++----------
>  1 file changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/lib/subcmd/Makefile b/tools/lib/subcmd/Makefile
> index 9a316d8b89df..b87213263a5e 100644
> --- a/tools/lib/subcmd/Makefile
> +++ b/tools/lib/subcmd/Makefile
> @@ -89,10 +89,10 @@ define do_install_mkdir
>  endef
>  
>  define do_install
> -	if [ ! -d '$(DESTDIR_SQ)$2' ]; then             \
> -		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$2'; \
> +	if [ ! -d '$2' ]; then             \
> +		$(INSTALL) -d -m 755 '$2'; \
>  	fi;                                             \
> -	$(INSTALL) $1 $(if $3,-m $3,) '$(DESTDIR_SQ)$2'
> +	$(INSTALL) $1 $(if $3,-m $3,) '$2'

What about using '$(INSTALL) -D ...' instead of the if-mkdir-block above?
(E.g. as in tools/debugging/Makefile.)

Kind regards,
Nicolas

>  endef
>  
>  install_lib: $(LIBFILE)
> @@ -100,13 +100,16 @@ install_lib: $(LIBFILE)
>  		$(call do_install_mkdir,$(libdir_SQ)); \
>  		cp -fpR $(LIBFILE) $(DESTDIR)$(libdir_SQ)
>  
> -install_headers:
> -	$(call QUIET_INSTALL, libsubcmd_headers) \
> -		$(call do_install,exec-cmd.h,$(prefix)/include/subcmd,644); \
> -		$(call do_install,help.h,$(prefix)/include/subcmd,644); \
> -		$(call do_install,pager.h,$(prefix)/include/subcmd,644); \
> -		$(call do_install,parse-options.h,$(prefix)/include/subcmd,644); \
> -		$(call do_install,run-command.h,$(prefix)/include/subcmd,644);
> +HDRS := exec-cmd.h help.h pager.h parse-options.h run-command.h
> +INSTALL_HDRS_PFX := $(DESTDIR)$(prefix)/include/subcmd
> +INSTALL_HDRS := $(addprefix $(INSTALL_HDRS_PFX)/, $(HDRS))
> +
> +$(INSTALL_HDRS): $(INSTALL_HDRS_PFX)/%.h: %.h
> +	$(call QUIET_INSTALL, $@) \
> +		$(call do_install,$<,$(INSTALL_HDRS_PFX)/,644)
> +
> +install_headers: $(INSTALL_HDRS)
> +	$(call QUIET_INSTALL, libsubcmd_headers)
>  
>  install: install_lib install_headers
>  
> -- 
> 2.39.0.rc0.267.gcb52ba06e7-goog

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