From: Greg KH <gregkh@linuxfoundation.org>
To: Fangrui Song <maskray@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com, stable@vger.kernel.org,
Jian Cai <jiancai@google.com>, Bill Wendling <morbo@google.com>,
Manoj Gupta <manojgupta@google.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>
Subject: Re: [PATCH v2] Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross compilation
Date: Tue, 21 Jul 2020 12:40:35 +0200 [thread overview]
Message-ID: <20200721104035.GC1676612@kroah.com> (raw)
In-Reply-To: <20200721041940.4029552-1-maskray@google.com>
On Mon, Jul 20, 2020 at 09:19:38PM -0700, Fangrui Song wrote:
> When CROSS_COMPILE is set (e.g. aarch64-linux-gnu-), if
> $(CROSS_COMPILE)elfedit is found at /usr/bin/aarch64-linux-gnu-elfedit,
> GCC_TOOLCHAIN_DIR will be set to /usr/bin/. --prefix= will be set to
> /usr/bin/ and Clang as of 11 will search for both
> $(prefix)aarch64-linux-gnu-$needle and $(prefix)$needle.
>
> GCC searchs for $(prefix)aarch64-linux-gnu/$version/$needle,
> $(prefix)aarch64-linux-gnu/$needle and $(prefix)$needle. In practice,
> $(prefix)aarch64-linux-gnu/$needle rarely contains executables.
>
> To better model how GCC's -B/--prefix takes in effect in practice, newer
> Clang (since
> https://github.com/llvm/llvm-project/commit/3452a0d8c17f7166f479706b293caf6ac76ffd90)
> only searches for $(prefix)$needle. Currently it will find /usr/bin/as
> instead of /usr/bin/aarch64-linux-gnu-as.
>
> Set --prefix= to $(GCC_TOOLCHAIN_DIR)$(CROSS_COMPILE)
> (/usr/bin/aarch64-linux-gnu-) so that newer Clang can find the
> appropriate cross compiling GNU as (when -no-integrated-as is in
> effect).
>
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Signed-off-by: Fangrui Song <maskray@google.com>
> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
> Tested-by: Nathan Chancellor <natechancellor@gmail.com>
> Tested-by: Nick Desaulniers <ndesaulniers@google.com>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1099
> ---
> Changes in v2:
> * Updated description to add tags and the llvm-project commit link.
> * Fixed a typo.
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
next prev parent reply other threads:[~2020-07-21 10:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 4:19 [PATCH v2] Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross compilation Fangrui Song
2020-07-21 10:40 ` Greg KH [this message]
2020-07-21 14:52 ` Sedat Dilek
2020-07-21 17:13 ` Nathan Chancellor
2020-07-21 19:54 ` Sedat Dilek
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