Re: [RFT] Testing 1.22

[Arnaldo <arnaldo.melo@gmail.com>]

On May 27, 2021 6:08:33 PM GMT-03:00, Jiri Olsa <jolsa@redhat.com> wrote:
>On Thu, May 27, 2021 at 01:41:13PM -0700, Andrii Nakryiko wrote:
>> On Thu, May 27, 2021 at 12:57 PM Arnaldo <arnaldo.melo@gmail.com>
>wrote:
>> >
>> >
>> >
>> > On May 27, 2021 4:14:17 PM GMT-03:00, Andrii Nakryiko
><andrii.nakryiko@gmail.com> wrote:
>> > >On Thu, May 27, 2021 at 12:06 PM Arnaldo <arnaldo.melo@gmail.com>
>> > >wrote:
>> > >>
>> > >>
>> > >>
>> > >> On May 27, 2021 1:54:40 PM GMT-03:00, Andrii Nakryiko
>> > ><andrii.nakryiko@gmail.com> wrote:
>> > >> >On Thu, May 27, 2021 at 8:20 AM Arnaldo Carvalho de Melo
>> > >> ><acme@kernel.org> wrote:
>> > >> >>
>> > >> >> Hi guys,
>> > >> >>
>> > >> >>         Its important to have 1.22 out of the door ASAP, so
>please
>> > >> >clone
>> > >> >> what is in tmp.master and report your results.
>> > >> >>
>> > >> >
>> > >> >Hey Arnaldo,
>> > >> >
>> > >> >If we are going to make pahole 1.22 a new mandatory minimal
>version
>> > >of
>> > >> >pahole, I think we should take a little bit of time and fix
>another
>> > >> >problematic issue and clean up Kbuild significantly.
>> > >> >
>> > >> >We discussed this before, it would be great to have an ability
>to
>> > >dump
>> > >> >generated BTF into a separate file instead of modifying vmlinux
>> > >image
>> > >> >in place. I'd say let's try to push for [0] to land as a
>temporary
>> > >> >work around to buy us a bit of time to implement this feature.
>Then,
>> > >> >when pahole 1.22 is released and packaged into major distros,
>we can
>> > >> >follow up in kernel with Kbuild clean ups and making pahole
>1.22
>> > >> >mandatory.
>> > >> >
>> > >> >What do you think? If anyone agrees, please consider chiming in
>on
>> > >the
>> > >> >above thread ([0]).
>> > >>
>> > >> There's multiple fixes that affects lots of stakeholders, so I'm
>more
>> > >inclined to release 1.22 sooner rather than later.
>> > >>
>> > >> If anyone has cycles right now to work on that detached BTF
>feature,
>> > >releasing 1.23 as soon as that feature is complete and tested
>shouldn't
>> > >be a problem.
>> > >>
>> > >> Then 1.23 the mandatory minimal version.
>> > >>
>> > >> Wdyt?
>> > >
>> > >If we make 1.22 mandatory there will be no good reason to make
>1.23
>> > >mandatory again. So I will have absolutely no inclination to work
>on
>> > >this, for example. So we are just wasting a chance to clean up the
>> > >Kbuild story w.r.t. pahole. And we are talking about just a few
>days
>> > >at most, while we do have a reasonable work around on the kernel
>side.
>> >
>> > So there were patches for stop using objcopy, which we thought
>could uncover some can of worms, were there patches for the detached
>BTF  file?
>> 
>> No, there weren't, if I remember correctly. What's the concern,
>> though? That detached BTF file isn't even an ELF, so it's
>> btf__get_raw_data() and write it to the file. Done.
>
>heya,
>I probably overlooked this, but are there more details about that
>detached BTF file feature somewhere? 


Look in the dwarves mailing list archives at lore, but it's just a new option to ask for the BTF data to be written to a file instead of to an ELF section, that will simplify the series of steps in the kernel building process.

I'll cook a patch early tomorrow.

- Arnaldo

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