Re: [PATCH] tools: perf: Fix liblk not built when using perf_install target

From: Namhyung Kim <namhyung@kernel.org>
To: Robert Richter <rric@kernel.org>
Cc: Sedat Dilek <sedat.dilek@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] tools: perf: Fix liblk not built when using perf_install target
Date: Tue, 03 Sep 2013 17:48:38 +0900	[thread overview]
Message-ID: <874na2uw7t.fsf@sejong.aot.lge.com> (raw)
In-Reply-To: <20130830164905.GA31061@rric.localhost> (Robert Richter's message of "Fri, 30 Aug 2013 18:49:05 +0200")

Hi,

On Fri, 30 Aug 2013 18:49:05 +0200, Robert Richter wrote:
> On 30.08.13 17:18:36, Sedat Dilek wrote:
>> So, I tried to build perf the "official" way:
>> 
>>    $ make -C tools/ perf_install
>> 
>> Unfortunately, my build breaks like this:
>> ...
>> make[2]: Entering directory
>> `~/src/linux-kernel/linux/tools/lib/traceevent'
>> make[2]: Leaving directory
>> `~/src/linux-kernel/linux/tools/lib/traceevent'
>>     LINK perf
>> gcc: error: ~/src/linux-kernel/linux/tools/lib/lk/liblk.a: No such file or directory
>> make[1]: *** [perf] Error 1
>> make[1]: Leaving directory `~/src/linux-kernel/linux/tools/perf'
>> make: *** [perf_install] Error 2
>> 
>> After some discussion on IRC with peterz and acme and a closer look at
>> the targets in "tools/Makefile", I have noticed that the perf_install
>> target misses liblk to be built beforehand.
>
> There are no build prerequisites on purpose for install targets.
> Install targets are intended to be run with root permissions. We don't
> want to create/overwrite files in the build directory as root while
> running install rules. Thus, you always need to run:
>
>  $ make -C tools/ perf
>
> or similar first.

But AFAIK install target usually depends on build targets on many
projects.  And perf too already does the same:

  [ tools/perf/Makefile ]
  install-bin: all
	...

  install: install-bin

So if you really concern the permission problem, install target should
not build perf itself, right?  But in this case, it tried to build perf
but failed to do it on liblk.

>
>> On the contrary the perf_clean target invokes to clean liblk when perf
>> is cleaned.
>> 
>> [ tools/Makefile ]
>> ...
>> perf_clean: liblk_clean
>> 	$(call descend,$(@:_clean=),clean)
>> ...
>> 
>> Fix this by adding liblk target to perf_install target.
>
> So no, this is not the proper fix.
>
> Before installing you *need* to build. You might want to fix the
> documenation...

Hmm.. I don't know.  What I'm curious about is why it didn't build liblk
during building perf.

Thanks,
Namhyung