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From:   Ian Rogers <irogers@google.com>
Date:   Wed, 3 May 2023 22:51:15 -0700
Message-ID: <CAP-5=fUNmiguiW+sv19EpGVVsrBD7dnVm4uMLOuutOo7_LUR=A@mail.gmail.com>
Subject: Re: [GIT PULL] perf tools changes for v6.4
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Clark Williams <williams@redhat.com>,
        Kate Carcia <kcarcia@redhat.com>, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org,
        Adrian Hunter <adrian.hunter@intel.com>,
        Changbin Du <changbin.du@huawei.com>,
        Hao Luo <haoluo@google.com>, James Clark <james.clark@arm.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Roman Lozko <lozko.roma@gmail.com>,
        Stephane Eranian <eranian@google.com>,
        Thomas Richter <tmricht@linux.ibm.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
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On Wed, May 3, 2023 at 8:12=E2=80=AFPM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Wed, May 3, 2023 at 8:00=E2=80=AFPM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > I did consider it, but the end result doesn't even build, so I unpulled=
 again..
> >
> > I get some libbpf error, and I'm just not interested in trying to
> > debug it. This has clearly not been tested well enough to be merged.
>
> Side note: its' not even about testing.
>
> The error message makes it clear that this is garbage and should never
> be merged even if it were to compile.
>
> There is not a way in hell that it is correct that a 'perf' tool build
> should ever even look at the vmlinux binary to build.
>
> The fact that it does shows that something is seriously wrong in
> perf-tool land, and I will not be touching any pulls until that
> fundamental mistake is entirely gone.
>
> The vmlinux image that is present in my tree (ie
> /home/torvalds/v2.6/linux/vmlinux) is a test build with an insane
> config. And the fact that the perf tool even looks at it is seriously
> broken.
>
> Whatever you are doing - stop it right now.
>
>                Linus

I think the error you gave makes it pretty clear what is going on and
Arnaldo's e-mail explains the motivation. Perhaps we can check a
vmlinux.h into the perf tree so that we don't default to generating
it. This would avoid the binary dependency but we may need different
flavors for different architectures because of structs like pt_regs.

Thanks,
Ian