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From:   Daniel Wagner <dwagner@suse.de>
To:     Daniel Bristot de Oliveira <bristot@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>
Cc:     linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Daniel Wagner <dwagner@suse.de>
Subject: [PATCH] tools/rtla: Explicitly list libtraceevent dependency
Date:   Tue, 10 Jan 2023 14:18:05 +0100
Message-Id: <20230110131805.16242-1-dwagner@suse.de>
MIME-Version: 1.0
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Precedence: bulk

The current libtracefs.pkg file lists the dependency on
libtraceevent ("pkg-config --libs libtracefs" -> "-ltracefs
-ltraceevent").

Dan Nicholson's Guide to pkg-config[1] stats that "Libs: The link
flags specific to this package and any required libraries that don't
support pkg-config". Thus the current libtracefs.pkg is not correct.

rtla is depending on libtraceevent but it doesn't express this in
'pkg-config' part to retrieve the correct build flags.

In order to be able to update the "Libs:" section in the libtracefs
project we need to list the dependency explicitly to avoid future linker
failures.

[1] https://people.freedesktop.org/~dbn/pkg-config-guide.html

Signed-off-by: Daniel Wagner <dwagner@suse.de>
---

I've got this fallout with because I am using libtraceevent and libtracefs build
with Meson. Meson generates different pkg files which seems to align with Dan's
Guide.

 tools/tracing/rtla/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
index 22e28b76f800..0664e2db22c1 100644
--- a/tools/tracing/rtla/Makefile
+++ b/tools/tracing/rtla/Makefile
@@ -32,7 +32,7 @@ TRACEFS_HEADERS	:= $$($(PKG_CONFIG) --cflags libtracefs)
 
 CFLAGS	:=	-O -g -DVERSION=\"$(VERSION)\" $(FOPTS) $(MOPTS) $(WOPTS) $(TRACEFS_HEADERS) $(EXTRA_CFLAGS)
 LDFLAGS	:=	-ggdb $(EXTRA_LDFLAGS)
-LIBS	:=	$$($(PKG_CONFIG) --libs libtracefs)
+LIBS	:=	$$($(PKG_CONFIG) --libs libtracefs libtraceevent)
 
 SRC	:=	$(wildcard src/*.c)
 HDR	:=	$(wildcard src/*.h)
-- 
2.39.0