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From: Sedat Dilek <sedat.dilek@gmail.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Tom Stellard <tstellar@redhat.com>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Jiri Olsa <jolsa@kernel.org>, Yonghong Song <yhs@fb.com>,
	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>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>, bpf <bpf@vger.kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Subject: Re: Check pahole availibity and BPF support of toolchain before starting a Linux kernel build
Date: Tue, 12 Jan 2021 21:47:30 +0100	[thread overview]
Message-ID: <CA+icZUU8MFFJMqFRAN7ekRzupPrS6WS5xGChUaFcjq2hfqW_wg@mail.gmail.com> (raw)
In-Reply-To: <20210112162156.GA1291051@krava>

Is it possible that someone tests with Nick Desaulniers's DWARF v5 patchset?

With b4 tool installed:

link="https://lore.kernel.org/r/CAKwvOdkZEiHK01OD420USb0j=F0LcrnRbauv9Yw26tu-GRbYkg@mail.gmail.com"
b4 -d am $link

...should give you a file which you can directly apply with git tool.

File: v3_20201203_ndesaulniers_kbuild_make_dwarf_version_a_choice.mbx

As my selfmade LLVM toolchain seems to be no good choice I jumped to gcc-10.

I see gazillions of DW_AT_ and DW_TAG_INVALID (0x48) warnings:

die__process_inline_expansion: DW_TAG_INVALID (0x48) @ <0x1c2a25e> not handled!

This might be due to DWARF version 5 patchset.
I did not check DWARF v2 (default) or DWARF v4 choices.

Beyond this, I noticed:

$ git grep LLVM_OBJCOPY scripts/ tools/
scripts/Makefile.modfinal:              LLVM_OBJCOPY=$(OBJCOPY)
$(PAHOLE) -J --btf_base vmlinux $@; \
scripts/link-vmlinux.sh:        LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
tools/testing/selftests/bpf/Makefile:LLVM_OBJCOPY       ?= llvm-objcopy

When only passing gcc-10 as compiler and ld.bfd as linker -
LLVM_OBJCOPY=objcopy is passed.
Means objcopy from GNU/binutils is used.
As far as I understand the code you want here llvm-objcopy
(scripts/Makefile.modfinal)?

I did a next tryout with gcc-10 and LLVM=1 means use all equivalent
LLVM tools to GNU/binutils.
Means use llvm-objcopy, llvm-nm, llvm-ar, llvm-objdump, etc.
Please see the link below under [1].

En plus, I tried pahole with Jirka "Convulted" Olsa (JCO) fix by passing...
   PAHOLE=/opt/pahole/bin/pahole
...to my make line.

Again I see that DW_TAG_INVALID (0x48) warnings.
Can someone enlighten me what that means?

Finally, with all that warnings observed I could "successfully"
generate Linux-kernel Debian packages.
I do NOT install software I do NOT trust - not booted - NoNoNo...

Thanks.

In the dark,
- Sedat -

[1] https://www.kernel.org/doc/html/latest/kbuild/llvm.html#llvm-utilities

  parent reply	other threads:[~2021-01-12 21:43 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11 12:48 Check pahole availibity and BPF support of toolchain before starting a Linux kernel build Sedat Dilek
2021-01-11 16:05 ` 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 [this message]
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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