Re: linux-next: build failure after merge of the perf tree

From: Ian Rogers <irogers@google.com>
To: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Next Mailing List <linux-next@vger.kernel.org>,
	namhyung@kernel.org
Subject: Re: linux-next: build failure after merge of the perf tree
Date: Wed, 22 Mar 2023 11:37:31 -0700	[thread overview]
Message-ID: <CAP-5=fUHqrQWPjk7QJB=r2Gzj7z5X3nL4bRuBAKzy2HvdSAr-A@mail.gmail.com> (raw)
In-Reply-To: <20230322083956.5c051777@canb.auug.org.au>

On Tue, Mar 21, 2023 at 2:40 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> Hi all,
>
> On Fri, 17 Mar 2023 09:50:25 +1100 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> >
> > After merging the perf tree, today's linux-next build (native perf)
> > failed like this:
> >
> > Auto-detecting system features:
> > ...                         clang-bpf-co-re: [  [32mon [m  ]
> > ...                                    llvm: [  [31mOFF [m ]
> > ...                                  libcap: [  [32mon [m  ]
> > ...                                  libbfd: [  [32mon [m  ]
> >
> > make[1]: *** Deleting file '/home/sfr/next/perf/util/bpf_skel/vmlinux.h'
> > libbpf: failed to find '.BTF' ELF section in /boot/vmlinux-6.0.0-5-powerpc64le
> > Error: failed to load BTF from /boot/vmlinux-6.0.0-5-powerpc64le: No data available
> > make[1]: *** [Makefile.perf:1075: /home/sfr/next/perf/util/bpf_skel/vmlinux.h] Error 195
> > make[1]: *** Waiting for unfinished jobs....
> > make: *** [Makefile.perf:236: sub-make] Error 2
> > Command exited with non-zero status 2
> >
> > To be clear this is a native build of perf on a PPC64le host using this
> > command line:
> >
> > make -C tools/perf -f Makefile.perf -s -O -j60 O=../perf EXTRA_CFLAGS=-Wno-psabi
> >
> > (I could probably remove the EXTRA_CLFAGS now that I am building with
> > gcc 12.2)
> >
> > I don't know which commit caused this.
> >
> > I have used the perf tree from next-20230316 for today.
>
> I am still getting this build failure.

Hi Stephen,

The build failure is intentional as not having BPF skeleton support in
the perf tool will remove features. I've just sent:
https://lore.kernel.org/lkml/20230322183108.1380882-1-irogers@google.com/
Which will recommend adding NO_BPF_SKEL=1 to your build options when
this failure occurs. I didn't think a features test was appropriate
for this as the feature test would basically replicate the vmlinux.h
generation and I didn't want to move that support through the build
system.

Thanks,
Ian

> --
> Cheers,
> Stephen Rothwell