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From: Sedat Dilek <sedat.dilek@gmail.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>
Cc: bpf@vger.kernel.org, linux-kbuild@vger.kernel.org
Subject: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build
Date: Mon, 11 Jan 2021 13:48:50 +0100	[thread overview]
Message-ID: <CA+icZUVuk5PVY4_HoCoY2ymd27UjuDi6kcAmFb_3=dqkvOA_Qw@mail.gmail.com> (raw)

Hi BPF maintainers and Mashiro,

Debian started to use CONFIG_DEBUG_INFO_BTF=y.

My kernel-build fails like this:

+ info BTFIDS vmlinux
+ [  != silent_ ]
+ printf   %-7s %s\n BTFIDS vmlinux
 BTFIDS  vmlinux
+ ./tools/bpf/resolve_btfids/resolve_btfids vmlinux
FAILED: load BTF from vmlinux: Invalid argument

The root cause is my selfmade LLVM toolchain has no BPF support.

$ which llc
/home/dileks/src/llvm-toolchain/install/bin/llc

$ llc --version
LLVM (http://llvm.org/):
 LLVM version 11.0.1
 Optimized build.
 Default target: x86_64-unknown-linux-gnu
 Host CPU: sandybridge

 Registered Targets:
   x86    - 32-bit X86: Pentium-Pro and above
   x86-64 - 64-bit X86: EM64T and AMD64

Debian's llc-11 shows me BPF support is built-in.

I see the breakag approx. 3 hours after the start of my kernel-build -
in the stage "vmlinux".
After 2 faulures in my build (2x 3 hours of build-time) I have still
no finished Linux v5.11-rc3 kernel.
This is a bit frustrating.

What about doing pre-checks - means before doing a single line of
compilation - to check for:
1. Required binaries
2. Required support of whatever feature in compiler, linker, toolchain etc.

Recently, I fell over depmod binary not found in my PATH - in one of
the last steps (modfinal) of the kernel build.

Any ideas to improve the situation?
( ...and please no RTFM, see links below. )

Thanks.

Regards,
- Sedat -


[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh#n144
[1] https://salsa.debian.org/kernel-team/linux/-/commit/929891281c61ce4403ddd869664c949692644a2f
[2] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html?highlight=pahole#llvm
[3] https://www.kernel.org/doc/html/latest/bpf/btf.html?highlight=pahole#btf-generation

             reply	other threads:[~2021-01-11 12:49 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11 12:48 Sedat Dilek [this message]
2021-01-11 16:05 ` Check pahole availibity and BPF support of toolchain before starting a Linux kernel build Yonghong Song
2021-01-11 17:56   ` Sedat Dilek
2021-01-11 21:03     ` Andrii Nakryiko
     [not found]       ` <CA+icZUVrF_LCVhELbNLA7=FzEZK4=jk3QLD9XT2w5bQNo=nnOA@mail.gmail.com>
2021-01-11 22:31         ` Jiri Olsa
2021-01-11 22:34           ` Tom Stellard
2021-01-12 10:46             ` Jiri Olsa
2021-01-12 13:10               ` Jiri Olsa
2021-01-12 16:14                 ` Sedat Dilek
2021-01-12 16:21                   ` Jiri Olsa
2021-01-12 17:18                     ` Sedat Dilek
2021-01-12 20:47                     ` Sedat Dilek
2021-01-12 21:36                       ` Sedat Dilek
2021-01-14 14:13           ` Sedat Dilek
2021-01-14 14:24             ` Jiri Olsa
2021-01-14 14:29               ` Sedat Dilek
     [not found]                 ` <CA+icZUXp5gkxCr+mybQ8uO3xx+rVmmRSnN7Dfx0Xmr+VQWyZAA@mail.gmail.com>
2021-01-14 15:13                   ` Sedat Dilek
2021-01-12  0:57         ` Yonghong Song
2021-01-12  4:09           ` Sedat Dilek

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