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Date:   Sat, 6 Aug 2022 14:22:03 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Daniel Bristot de Oliveira <bristot@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Andreas Schwab <schwab@suse.de>,
        jianchunfu <jianchunfu@cmss.chinamobile.com>
Subject: Re: [GIT PULL] rtla: Updates for 5.20/6.0
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On Sat, 6 Aug 2022 08:52:29 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> For extra bonus points, if you can state all missing packages in one
> go (instead of "oops you don't have Xyz" followed by install of Xyz,
> followed by "Oops, now you don't have Abc") that would be nice too.
> 
> But at this point the fundamental problem with incomprehensible error
> messages is long gone, so it's not a big deal and not worth lots of
> effort. More of a "if it's easy enough.."

With the below patch, it will show the warnings for both libtraceevent and
libtracefs if they are not installed:

 $ make
********************************************
** NOTICE: libtraceevent version 1.5 or higher not found
**
** Consider installing the latest libtraceevent from your
** distribution, e.g., 'dnf install libtraceevent-devel' on Fedora,
** or from source:
**
**  https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
**
********************************************
********************************************
** NOTICE: libtracefs version 1.3 or higher not found
**
** Consider installing the latest libtracefs from your
** distribution, e.g., 'dnf install libtracefs-devel' on Fedora,
** or from source:
**
**  https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
**
********************************************
Makefile:106: *** Please add the necessary dependencies.  Stop.

-- Steve

diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
index 1bea2d16d4c1..a8c89b5b8fa5 100644
--- a/tools/tracing/rtla/Makefile
+++ b/tools/tracing/rtla/Makefile
@@ -61,15 +61,19 @@ endif
 LIBTRACEEVENT_MIN_VERSION = 1.5
 LIBTRACEFS_MIN_VERSION = 1.3
 
+.PHONY:	all warnings
+all:	warnings rtla
+
 TEST_LIBTRACEEVENT = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEEVENT_MIN_VERSION) libtraceevent > /dev/null 2>&1 || echo n")
 ifeq ("$(TEST_LIBTRACEEVENT)", "n")
+WARNINGS += warning_traceevent
 .PHONY: warning_traceevent
 warning_traceevent:
 	@echo "********************************************"
 	@echo "** NOTICE: libtraceevent version $(LIBTRACEEVENT_MIN_VERSION) or higher not found"
 	@echo "**"
 	@echo "** Consider installing the latest libtraceevent from your"
-	@echo "** distribution, e.g., 'dnf install libtraceevent' on Fedora,"
+	@echo "** distribution, e.g., 'dnf install libtraceevent-devel' on Fedora,"
 	@echo "** or from source:"
 	@echo "**"
 	@echo "**  https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/ "
@@ -80,12 +84,13 @@ endif
 TEST_LIBTRACEFS = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEFS_MIN_VERSION) libtracefs > /dev/null 2>&1 || echo n")
 ifeq ("$(TEST_LIBTRACEFS)", "n")
 .PHONY: warning_tracefs
+WARNINGS += warning_tracefs
 warning_tracefs:
 	@echo "********************************************"
 	@echo "** NOTICE: libtracefs version $(LIBTRACEFS_MIN_VERSION) or higher not found"
 	@echo "**"
 	@echo "** Consider installing the latest libtracefs from your"
-	@echo "** distribution, e.g., 'dnf install libtracefs' on Fedora,"
+	@echo "** distribution, e.g., 'dnf install libtracefs-devel' on Fedora,"
 	@echo "** or from source:"
 	@echo "**"
 	@echo "**  https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ "
@@ -93,8 +98,12 @@ warning_tracefs:
 	@echo "********************************************"
 endif
 
-.PHONY:	all
-all:	rtla
+ifneq ("$(WARNINGS)", "")
+ERROR_OUT = $(error Please add the necessary dependencies)
+endif
+
+warnings: $(WARNINGS)
+	$(ERROR_OUT)
 
 rtla: $(OBJ)
 	$(CC) -o rtla $(LDFLAGS) $(OBJ) $(LIBS)