Re: [PATCH] samples/bpf/Makefile: Create tools/testing/selftests/bpf dir

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Hui Zhu <teawater@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	john fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	Hui Zhu <teawaterz@linux.alibaba.com>
Subject: Re: [PATCH] samples/bpf/Makefile: Create tools/testing/selftests/bpf dir
Date: Tue, 15 Dec 2020 14:08:34 -0800	[thread overview]
Message-ID: <CAEf4BzaQ9PsMrxwP2WW2eTDZ6LLYZRFUwJUa2xpFAPhBJu01PQ@mail.gmail.com> (raw)
In-Reply-To: <20201214105654.5048-1-teawater@gmail.com>

On Mon, Dec 14, 2020 at 2:57 AM Hui Zhu <teawater@gmail.com> wrote:
>
> From: Hui Zhu <teawaterz@linux.alibaba.com>
>
> Got an error when I built samples/bpf in a separate directory:
> make O=../bk/ defconfig
> make -j64 bzImage
> make headers_install
> make V=1 M=samples/bpf
> ...
> ...
> make -C /home/teawater/kernel/linux/samples/bpf/../..//tools/build
> CFLAGS= LDFLAGS= fixdep
> make -f
> /home/teawater/kernel/linux/samples/bpf/../..//tools/build/Makefile.build
> dir=. obj=fixdep
> make all_cmd
> Warning: Kernel ABI header at 'tools/include/uapi/linux/netlink.h'
> differs from latest version at 'include/uapi/linux/netlink.h'
> Warning: Kernel ABI header at 'tools/include/uapi/linux/if_link.h'
> differs from latest version at 'include/uapi/linux/if_link.h'
>   gcc
> -Wp,-MD,samples/bpf/../../tools/testing/selftests/bpf/.cgroup_helpers.o.d
> -Wall -O2 -Wmissing-prototypes -Wstrict-prototypes -I./usr/include
> -I/home/teawater/kernel/linux/tools/testing/selftests/bpf/
> -I/home/teawater/kernel/linux/tools/lib/
> -I/home/teawater/kernel/linux/tools/include
> -I/home/teawater/kernel/linux/tools/perf -DHAVE_ATTR_TEST=0  -c -o
> samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.o
> /home/teawater/kernel/linux/samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c
> /home/teawater/kernel/linux/samples/bpf/../../tools/testing/selftests/bpf/cgroup_helpers.c:315:1:
> fatal error: opening dependency file
> samples/bpf/../../tools/testing/selftests/bpf/.cgroup_helpers.o.d: No
> such file or directory
>
> ls -al samples/bpf/../../tools/testing/selftests/bpf/
> ls: cannot access 'samples/bpf/../../tools/testing/selftests/bpf/': No
> such file or directory
>
> There is no samples/bpf/../../tools/testing/selftests/bpf/ causing a
> compilation error.
>
> This commit add a "make -p" before build files in
> samples/bpf/../../tools/testing/selftests/bpf/ to handle the issue.
>
> Signed-off-by: Hui Zhu <teawaterz@linux.alibaba.com>
> ---
>  samples/bpf/Makefile | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index aeebf5d12f32..5b940eedf2e8 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -262,6 +262,7 @@ clean:
>
>  $(LIBBPF): FORCE
>  # Fix up variables inherited from Kbuild that tools/ build system won't like
> +       mkdir -p $(obj)/../../tools/testing/selftests/bpf/

This is not a real fix, rather ad-hoc work-around. Let's try to
understand why this path is necessary and do adjustments to either
samples' or libbpf's Makefile to work in such cases.

>         $(MAKE) -C $(dir $@) RM='rm -rf' EXTRA_CFLAGS="$(TPROGS_CFLAGS)" \
>                 LDFLAGS=$(TPROGS_LDFLAGS) srctree=$(BPF_SAMPLES_PATH)/../../ O=
>
> --
> 2.17.1
>