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Date:   Fri, 23 Jun 2023 08:06:05 -0700
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Subject: Re: [PATCH] bpf: Replace deprecated -target with --target= for Clang
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To:     Fangrui Song <maskray@google.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        John Fastabend <john.fastabend@gmail.com>,
        Quentin Monnet <quentin@isovalent.com>, bpf@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, llvm@lists.linux.dev
References: <20230623020908.1410959-1-maskray@google.com>
From:   Yonghong Song <yhs@meta.com>
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On 6/22/23 7:09 PM, Fangrui Song wrote:
> -target has been deprecated since Clang 3.4 in 2013. Use the preferred
> --target=bpf form instead. This matches how we use --target= in
> scripts/Makefile.clang.
> 
> Signed-off-by: Fangrui Song <maskray@google.com>

LGTM with a few nits below. As Daniel mentioned earlier. It would be
to separate tools/perf changes to a separate patch to perf subsystem.
Please also cc
    bpf@vger.kernel.org

Acked-by: Yonghong Song <yhs@fb.com>


> ---
>   Documentation/bpf/bpf_devel_QA.rst              | 10 +++++-----
>   Documentation/bpf/btf.rst                       |  4 ++--
>   Documentation/bpf/llvm_reloc.rst                |  6 +++---
>   drivers/hid/bpf/entrypoints/Makefile            |  2 +-
>   kernel/bpf/preload/iterators/Makefile           |  2 +-
>   samples/bpf/Makefile                            |  6 +++---
>   samples/bpf/gnu/stubs.h                         |  3 ++-
>   samples/bpf/test_lwt_bpf.sh                     |  2 +-
>   samples/hid/Makefile                            |  6 +++---
>   tools/bpf/bpftool/Documentation/bpftool-gen.rst |  4 ++--
>   tools/bpf/bpftool/Makefile                      |  2 +-
>   tools/bpf/runqslower/Makefile                   |  2 +-
>   tools/build/feature/Makefile                    |  2 +-
>   tools/perf/Documentation/perf-config.txt        |  2 +-
>   tools/perf/Makefile.perf                        |  4 ++--
>   tools/perf/util/llvm-utils.c                    |  4 ++--
>   tools/testing/selftests/bpf/Makefile            |  6 +++---
>   tools/testing/selftests/bpf/gnu/stubs.h         |  3 ++-
>   tools/testing/selftests/hid/Makefile            |  6 +++---
>   tools/testing/selftests/net/Makefile            |  4 ++--
>   tools/testing/selftests/tc-testing/Makefile     |  2 +-
>   21 files changed, 42 insertions(+), 40 deletions(-)
> 
[...]
> diff --git a/samples/bpf/gnu/stubs.h b/samples/bpf/gnu/stubs.h
> index 719225b16626..cc37155fbfa5 100644
> --- a/samples/bpf/gnu/stubs.h
> +++ b/samples/bpf/gnu/stubs.h
> @@ -1 +1,2 @@
> -/* dummy .h to trick /usr/include/features.h to work with 'clang -target bpf' */
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* dummy .h to trick /usr/include/features.h to work with 'clang --target=bpf' */

Quentin and Daniel already mentioned this one. The SPDX license
change can be removed. This is irrelavent to the theme of this patch.


[...]
> diff --git a/tools/testing/selftests/bpf/gnu/stubs.h b/tools/testing/selftests/bpf/gnu/stubs.h
> index 719225b16626..cc37155fbfa5 100644
> --- a/tools/testing/selftests/bpf/gnu/stubs.h
> +++ b/tools/testing/selftests/bpf/gnu/stubs.h
> @@ -1 +1,2 @@
> -/* dummy .h to trick /usr/include/features.h to work with 'clang -target bpf' */
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* dummy .h to trick /usr/include/features.h to work with 'clang --target=bpf' */

Here is another place that the SPDX license is not needed.

> diff --git a/tools/testing/selftests/hid/Makefile b/tools/testing/selftests/hid/Makefile
> index 01c0491d64da..2e986cbf1a46 100644
> --- a/tools/testing/selftests/hid/Makefile
> +++ b/tools/testing/selftests/hid/Makefile
> @@ -167,7 +167,7 @@ $(RESOLVE_BTFIDS): $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/resolve_btfids	\
>   		OUTPUT=$(HOST_BUILD_DIR)/resolve_btfids/ BPFOBJ=$(HOST_BPFOBJ)
>   
>   # Get Clang's default includes on this system, as opposed to those seen by
> -# '-target bpf'. This fixes "missing" files on some architectures/distros,
> +# '--target=bpf'. This fixes "missing" files on some architectures/distros,
[...]