Re: [PATCH v2 1/6] perf build: Conditionally add feature check flags for libtrace{event,fs}

[Namhyung Kim <namhyung@kernel.org>]

Hello,

On Fri, Jun 28, 2024 at 10:34:27PM +0200, Guilherme Amadio wrote:
> This avoids reported warnings when the packages are not installed.
> 
> Fixes: 0f0e1f44569061e3dc590cd0b8cb74d8fd53706b
> Signed-off-by: Guilherme Amadio <amadio@gentoo.org>

Thanks for working on this.

> ---
>  tools/perf/Makefile.config | 28 +++++++++++++++-------------
>  1 file changed, 15 insertions(+), 13 deletions(-)
> 
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 5271a4c1d2b3..5387babb8f04 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -182,13 +182,21 @@ endif
>  FEATURE_CHECK_CFLAGS-libzstd := $(LIBZSTD_CFLAGS)
>  FEATURE_CHECK_LDFLAGS-libzstd := $(LIBZSTD_LDFLAGS)
>  
> -# for linking with debug library, run like:
> -# make DEBUG=1 PKG_CONFIG_PATH=/opt/libtraceevent/(lib|lib64)/pkgconfig
> -FEATURE_CHECK_CFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --cflags libtraceevent)
> -FEATURE_CHECK_LDFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --libs libtraceevent)
> -
> -FEATURE_CHECK_CFLAGS-libtracefs := $(shell $(PKG_CONFIG) --cflags libtracefs)
> -FEATURE_CHECK_LDFLAGS-libtracefs := $(shell $(PKG_CONFIG) --libs libtracefs)
> +ifneq ($(NO_LIBTRACEEVENT),1)
> +  ifeq ($(call get-executable,$(PKG_CONFIG)),)
> +  dummy := $(error Error: $(PKG_CONFIG) needed by libtraceevent is missing on this system, please install it)

I know you just copied the code, but IIRC we wanted to remove this dummy
assignment before.

> +  endif
> +endif
> +ifeq ($(shell $(PKG_CONFIG) --exists libtraceevent 2>&1 1>/dev/null; echo $$?),0)
> +  # for linking with debug library, run like:
> +  # make DEBUG=1 PKG_CONFIG_PATH=/opt/libtraceevent/(lib|lib64)/pkgconfig
> +  FEATURE_CHECK_CFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --cflags libtraceevent)
> +  FEATURE_CHECK_LDFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --libs libtraceevent)
> +endif
> +ifeq ($(shell $(PKG_CONFIG) --exists libtracefs 2>&1 1>/dev/null; echo $$?),0)
> +  FEATURE_CHECK_CFLAGS-libtracefs := $(shell $(PKG_CONFIG) --cflags libtracefs)
> +  FEATURE_CHECK_LDFLAGS-libtracefs := $(shell $(PKG_CONFIG) --libs libtracefs)

I'm curious if we can redirect stderr to /dev/null to surpress the
output when pkg-config is not installed.  Then we don't need to check
the `ifeq`.

Thanks,
Namhyung


> +endif
>  
>  FEATURE_CHECK_CFLAGS-bpf = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(SRCARCH)/include/uapi -I$(srctree)/tools/include/uapi
>  # include ARCH specific config
> @@ -208,12 +216,6 @@ ifeq ($(call get-executable,$(BISON)),)
>    $(error Error: $(BISON) is missing on this system, please install it)
>  endif
>  
> -ifneq ($(NO_LIBTRACEEVENT),1)
> -  ifeq ($(call get-executable,$(PKG_CONFIG)),)
> -  dummy := $(error Error: $(PKG_CONFIG) needed by libtraceevent is missing on this system, please install it)
> -  endif
> -endif
> -
>  ifneq ($(OUTPUT),)
>    ifeq ($(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/\1\2\3/g') \>\= 371), 1)
>      BISON_FILE_PREFIX_MAP := --file-prefix-map=$(OUTPUT)=
> -- 
> 2.45.2
>