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From: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>
To: Jiri Olsa <olsajiri@gmail.com>, Arnaldo Carvalho de Melo
 <acme@redhat.com>, Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: linux-kernel@vger.kernel.org, =?utf-8?B?QmrDtnJuIFTDtnBlbA==?=
 <bjorn@rivosinc.com>, Nathan
 Chancellor <nathan@kernel.org>, Nick Desaulniers
 <ndesaulniers@google.com>, Tom Rix <trix@redhat.com>, bpf@vger.kernel.org,
 Anders Roxell <anders.roxell@linaro.org>, llvm@lists.linux.dev, Jiri Olsa
 <olsajiri@gmail.com>
Subject: Re: [PATCH v2] tools/build: Add clang cross-compilation flags to
 feature detection
In-Reply-To: <ZUOWcXDpCOzxbFW0@krava>
References: <20231102103252.247147-1-bjorn@kernel.org> <ZUOWcXDpCOzxbFW0@krava>
Date: Fri, 26 Apr 2024 12:31:17 +0200
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Jiri Olsa <olsajiri@gmail.com> writes:

> On Thu, Nov 02, 2023 at 11:32:52AM +0100, Bj=C3=B6rn T=C3=B6pel wrote:
>> From: Bj=C3=B6rn T=C3=B6pel <bjorn@rivosinc.com>
>>=20
>> When a tool cross-build has LLVM=3D1 set, the clang cross-compilation
>> flags are not passed to the feature detection build system. This
>> results in the host's features are detected instead of the targets.
>>=20
>> E.g, triggering a cross-build of bpftool:
>>=20
>>   cd tools/bpf/bpftool
>>   make ARCH=3Driscv CROSS_COMPILE=3Driscv64-linux-gnu- LLVM=3D1
>>=20
>> would report the host's, and not the target's features.
>>=20
>> Correct the issue by passing the CLANG_CROSS_FLAGS variable to the
>> feature detection makefile.
>>=20
>> Fixes: cebdb7374577 ("tools: Help cross-building with clang")
>> Signed-off-by: Bj=C3=B6rn T=C3=B6pel <bjorn@rivosinc.com>
>
> Acked-by: Jiri Olsa <jolsa@kernel.org>

Waking up the dead!

Arnaldo, Jean-Philippe: I'm still stung by what this patch fixes. LMK
what you need from me/this patch to pick it up.


Cheers,
Bj=C3=B6rn