Re: [net-next PATCH 4/4] samples/bpf: allow make to be run from samples/bpf/ directory

From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: netdev@vger.kernel.org, bblanco@plumgrid.com,
	borkmann@iogearbox.net, linux-kbuild@vger.kernel.org
Subject: Re: [net-next PATCH 4/4] samples/bpf: allow make to be run from samples/bpf/ directory
Date: Tue, 26 Apr 2016 07:35:25 -0700	[thread overview]
Message-ID: <20160426143524.GB39797@ast-mbp.thefacebook.com> (raw)
In-Reply-To: <20160426110932.20716.51360.stgit@firesoul>

On Tue, Apr 26, 2016 at 01:09:32PM +0200, Jesper Dangaard Brouer wrote:
> It is not intuitive that 'make' must be run from the top level
> directory with argument "samples/bpf/" to compile these eBPF samples.
> 
> Introduce a kbuild make file trick that allow make to be run from the
> "samples/bpf/" directory itself.  It basically change to the top level
> directory and call "make samples/bpf/" with the "/" slash after the
> directory name.
> 
> Also add a clean target that only cleans this directory, by taking
> advantage of the kbuild external module setting M=$PWD.
> 
> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> ---
>  samples/bpf/Makefile   |    8 ++++++++
>  samples/bpf/README.rst |    3 +++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 7ac66f5bbbf5..7370dfee482f 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -85,6 +85,14 @@ HOSTLOADLIBES_test_overhead += -lelf -lrt
>  #  make samples/bpf/ LLC=~/git/llvm/build/bin/llc
>  LLC ?= llc
>  
> +# Trick to allow make to be run from this directory
> +all:
> +	$(MAKE) -C ../../ $$PWD/
> +
> +clean:
> +	$(MAKE) -C ../../ M=$$PWD clean
> +	@rm -f *~
> +

nice trick!