Re: selftests: bpf: test_libbpf.sh failed at file test_l4lb.o

From: Dan Rue <dan.rue@linaro.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Naresh Kamboju <naresh.kamboju@linaro.org>,
	"open list:KERNEL SELFTEST FRAMEWORK" 
	<linux-kselftest@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Netdev <netdev@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	Xdp <xdp-newbies@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Alexei Starovoitov <ast@kernel.org>, Martin Lau <kafai@fb.com>,
	Yonghong Song <yhs@fb.com>,
	john fastabend <john.fastabend@gmail.com>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	Shuah Khan <shuah@kernel.org>
Subject: Re: selftests: bpf: test_libbpf.sh failed at file test_l4lb.o
Date: Tue, 25 Jun 2019 10:31:59 -0500	[thread overview]
Message-ID: <20190625153159.5utnn36dgku5545n@xps.therub.org> (raw)
In-Reply-To: <CAADnVQKZycXgSw6C0qa7g0y=W3xRhM_4Rqcj7ZzL=rGh_n4mgA@mail.gmail.com>

On Mon, Jun 24, 2019 at 12:58:15PM -0700, Alexei Starovoitov wrote:
> On Mon, Jun 24, 2019 at 12:53 PM Dan Rue <dan.rue@linaro.org> wrote:
> >
> > I would say if it's not possible to check at runtime, and it requires
> > clang 9.0, that this test should not be enabled by default.
> 
> The latest clang is the requirement.
> If environment has old clang or no clang at all these tests will be failing.

Hi Alexei!

I'm not certain if I'm interpreting you as you intended, but it sounds
like you're telling me that if the test build environment does not use
'latest clang' (i guess latest as of today?), that these tests will
fail, and that is how it is going to be. If I have that wrong, please
correct me and disregard the rest of my message.

Please understand where we are coming from. We (and many others) run
thousands of tests from a lot of test frameworks, and so our environment
often has mutually exclusive requirements when it comes to things like
toolchain selection.

We believe, strongly, that a test should not emit a "fail" for a missing
requirement. Fail is a serious thing, and should be reserved for an
actual issue that needs to be investigated, reported, and fixed.

This is how we treat test failures - we investigate, report, and fix
them when possible. When they're not real failures, we waste our time
(and yours, in this case).

By adding the tests to TEST_GEN_PROGS, you're adding them to the general
test set that those of us running test farms try to run continuously
across a wide range of hardware environments and kernel branches.

My suggestion is that if you do not want us running them, don't add them
to TEST_GEN_PROGS. I thought the suggestion of testing for adequate
clang support and adding them conditionally at build-time was an idea
worth consideration.

Thanks,
Dan

-- 
Linaro - Kernel Validation