Re: [PATCH v2] samples/bpf: Add more instructions to build dependencies and, configuration in README.rst - Stanislav Fomichev via Linux-kernel-mentees

From: Stanislav Fomichev via Linux-kernel-mentees <linux-kernel-mentees@lists.linuxfoundation.org>
To: Anh Tuan Phan <tuananhlfc@gmail.com>
Cc: daniel@iogearbox.net, martin.lau@linux.dev, ast@kernel.org,
	andrii@kernel.org, bpf@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH v2] samples/bpf: Add more instructions to build dependencies and, configuration in README.rst
Date: Thu, 6 Jul 2023 11:16:27 -0700	[thread overview]
Message-ID: <ZKcE+wMWGdVFSBX2@google.com> (raw)
In-Reply-To: <bd1477f2-a51e-a795-4f25-a32d6ab46530@gmail.com>

On 07/06, Anh Tuan Phan wrote:
> Update the Documentation to mention that some samples require pahole
> v1.16 and kernel built with CONFIG_DEBUG_INFO_BTF=y
> 
> Signed-off-by: Anh Tuan Phan <tuananhlfc@gmail.com>
> ---
>  samples/bpf/README.rst | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/samples/bpf/README.rst b/samples/bpf/README.rst
> index 57f93edd1957..631592b83d60 100644
> --- a/samples/bpf/README.rst
> +++ b/samples/bpf/README.rst
> @@ -14,6 +14,9 @@ Compiling requires having installed:
>  Note that LLVM's tool 'llc' must support target 'bpf', list version
>  and supported targets with command: ``llc --version``
> 
> +Some samples require pahole version 1.16 as a dependency. See
> +https://docs.kernel.org/bpf/bpf_devel_QA.html for reference.
> +

Any reason no to add pahole 1.16 to this section above?

Compiling requires having installed:
 * clang >= version 3.4.0
 * llvm >= version 3.7.1
 * pahole >= version 1.16

Although clang 3.4 probably won't get you anywhere these days. The
whole README seems a bit outdated :-)

>  Clean and configuration
>  -----------------------
> 
> @@ -28,6 +31,10 @@ Configure kernel, defconfig for instance::
> 
>   make defconfig
> 
> +Some samples require support for BPF Type Format (BTF). To enable it,
> open the
> +generated config file, or use menuconfig (by "make menuconfig") to
> enable the
> +following configs: CONFIG_BPF_SYSCALL and CONFIG_DEBUG_INFO_BTF.
> +

This is usually enabled by default, so why special case it here?
Maybe, if you want some hints about the config, we should add
a reference to tools/testing/selftests/bpf/config ?

>  Kernel headers
>  --------------
> 
> -- 
> 2.34.1
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