Re: [PATCH v2] samples/bpf: Add more instructions to build dependencies and, configuration in README.rst

[Stanislav Fomichev via Linux-kernel-mentees <linux-kernel-mentees@lists.linuxfoundation.org>]

On 07/07, Anh Tuan Phan wrote:
> 
> 
> On 7/7/23 01:16, Stanislav Fomichev wrote:
> > 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 whole README seems a bit outdated :-)
> >
> 
> Put pahole requirement as your idea is better, thanks for suggestion.
> Will update it and clang version as well. For clang version, I think I
> can update min version as 11.0.0 (reference from
> https://www.kernel.org/doc/html/next/process/changes.html). Do you see
> any other potential outdated things in this document? I follow the above
> steps and it help me compile the sample code successfully.

Maybe we can reference that doc instead here? Otherwise that copy-pasted
11.0.0 will also get old. Just mention here that we need
clang/llvm/pahole to compile the samples and for specific versions
put a link to process/changes.rst
 
> >>  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 ?
> > 
> 
> The config CONFIG_DEBUG_INFO_BTF is disabled for some distros at least
> for mine. I ran "make defconfig" and it's not enabled by default so I
> think it worth to mention it here to help novice get started. I'll
> update it to reference to tools/testing/selftests/bpf/config .
> 
> >>  Kernel headers
> >>  --------------
> >>
> >> -- 
> >> 2.34.1
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