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Date:   Tue, 11 Jul 2023 10:06:00 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Thomas Richter <tmricht@linux.ibm.com>
Cc:     linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
        jolsa@kernel.org, rostedt@goodmis.org, svens@linux.ibm.com,
        gor@linux.ibm.com, sumanthk@linux.ibm.com, hca@linux.ibm.com
Subject: Re: [PATCH] perf/build: fix broken dependency check for libtracefs
Message-ID: <ZK1TuFAK0VL5vfR5@kernel.org>
References: <20230711124019.3167321-1-tmricht@linux.ibm.com>
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Em Tue, Jul 11, 2023 at 02:40:19PM +0200, Thomas Richter escreveu:
> Perf build auto-detects features and packages already installed
> for its build. This is done in directory tools/build/feature. This
> directory contains small sample programs. When they successfully
> compile the necessary prereqs in form of libraries and header
> files are present.
> 
> Such a check is also done for libtracefs. And this check fails:
> 
> Output before:
>  # rm -f test-libtracefs.bin; make test-libtracefs.bin
>  gcc  -MD -Wall -Werror -o test-libtracefs.bin test-libtracefs.c \
> 	 > test-libtracefs.make.output 2>&1 -ltracefs
>  make: *** [Makefile:211: test-libtracefs.bin] Error 1
>  # cat test-libtracefs.make.output
>  In file included from test-libtracefs.c:2:
>  /usr/include/tracefs/tracefs.h:11:10: fatal error: \
> 	 event-parse.h: No such file or directory
>    11 | #include <event-parse.h>
>       |          ^~~~~~~~~~~~~~~
>  compilation terminated.
>  #
> 
> The root cause of this compile error is
> commit 880885d9c22e ("libtracefs: Remove "traceevent/" from referencing libtraceevent headers")
> in the libtracefs project hosted here:
>  https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
> 
> That mentioned patch removes the traceevent/ directory name from
> the include statement, causing the file not to be included even
> when the libtraceevent-devel package is installed. This package contains
> the file referred to in tracefs/tracefs.h:
>  # rpm -ql libtraceevent-devel
>  /usr/include/traceevent
>  /usr/include/traceevent/event-parse.h  <----- here
>  /usr/include/traceevent/event-utils.h
>  /usr/include/traceevent/kbuffer.h
>  /usr/include/traceevent/trace-seq.h
>  /usr/lib64/libtraceevent.so
>  /usr/lib64/pkgconfig/libtraceevent.pc

Ok, but since libtraceevent comes with a pkgconfig file, shouldn't we
use it instead?

Something like:

⬢[acme@toolbox perf-tools]$ pkgconf --cflags libtraceevent
-I/usr/include/traceevent

look for PKG_CONFIG in the perf makefiles, I see things like:

  FLAGS_GTK2=$(CFLAGS) $(LDFLAGS) $(EXTLIBS) $(shell $(PKG_CONFIG) --libs --cflags gtk+-2.0 2>/dev/null)

etc.

- Arnaldo

>  #
> 
> With this patch the compile succeeds.
> 
> Output after:
>  # rm -f test-libtracefs.bin; make test-libtracefs.bin
>  gcc  -MD -Wall -Werror -o test-libtracefs.bin test-libtracefs.c \
> 	 > test-libtracefs.make.output 2>&1 -I/usr/include/traceevent -ltracefs
>  #
> 
> Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
> Cc: jolsa@kernel.org
> Cc: rostedt@goodmis.org
> ---
>  tools/build/feature/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> index 0f0aa9b7d7b5..764b0234161f 100644
> --- a/tools/build/feature/Makefile
> +++ b/tools/build/feature/Makefile
> @@ -208,7 +208,7 @@ $(OUTPUT)test-libtraceevent.bin:
>  	$(BUILD) -ltraceevent
>  
>  $(OUTPUT)test-libtracefs.bin:
> -	$(BUILD) -ltracefs
> +	 $(BUILD) -I/usr/include/traceevent -ltracefs
>  
>  $(OUTPUT)test-libcrypto.bin:
>  	$(BUILD) -lcrypto
> -- 
> 2.41.0
> 

-- 

- Arnaldo