Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220802015052.10452-1-ojeda@kernel.org> <20220802015052.10452-28-ojeda@kernel.org>
In-Reply-To: <20220802015052.10452-28-ojeda@kernel.org>
From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 17 Aug 2022 16:39:57 +0200
Message-ID: <CAK8P3a0jqhGY9E85VC9gNem5q6-dWeq0H6-7bhJopinMnLtOKQ@mail.gmail.com>
Subject: Re: [PATCH v8 27/31] Kbuild: add Rust support
To:     Miguel Ojeda <ojeda@kernel.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sven Van Asbroeck <thesven73@gmail.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Miguel Cano <macanroj@gmail.com>,
        Paul Mackerras <paulus@samba.org>, Gary Guo <gary@garyguo.net>,
        Douglas Su <d0u9.su@outlook.com>,
        Borislav Petkov <bp@alien8.de>,
        linux-riscv@lists.infradead.org, Will Deacon <will@kernel.org>,
        Martin Rodriguez Reboredo <yakoyoku@gmail.com>,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Masahiro Yamada <masahiroy@kernel.org>, x86@kernel.org,
        Russell King <linux@armlinux.org.uk>,
        Ingo Molnar <mingo@redhat.com>,
        Wedson Almeida Filho <wedsonaf@google.com>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Antonio Terceiro <antonio.terceiro@linaro.org>,
        Adam Bratschi-Kaye <ark.email@gmail.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org,
        Boqun Feng <boqun.feng@gmail.com>,
        linux-um@lists.infradead.org,
        =?UTF-8?Q?Bj=C3=83B_6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Daniel Xu <dxu@dxuuu.xyz>, David Gow <davidgow@google.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Dariusz Sosnowski <dsosnowski@dsosnowski.pl>,
        linux-arm-kernel@lists.infradead.org,
        Tiago Lam <tiagolam@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Nick Desaulniers <ndesaulniers@google.com>,
        linux-kernel@vger.kernel.org,
        Boris-Chengbiao Zhou <bobo1239@web.de>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Richard Weinberger <richard@nod.at>,
        Finn Behrens <me@kloenk.de>,
        Johannes Berg <johannes@sipsolutions.net>,
        linuxppc-dev@lists.ozlabs.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Aug 2, 2022 at 3:50 AM Miguel Ojeda <ojeda@kernel.org> wrote:
>
> +# These flags apply to all Rust code in the tree, including the kernel and
> +# host programs.
> +export rust_common_flags := --edition=2021 \
> +                           -Zbinary_dep_depinfo=y \
> +                           -Dunsafe_op_in_unsafe_fn -Drust_2018_idioms \
> +                           -Dunreachable_pub -Dnon_ascii_idents \
> +                           -Wmissing_docs \
> +                           -Drustdoc::missing_crate_level_docs \
> +                           -Dclippy::correctness -Dclippy::style \
> +                           -Dclippy::suspicious -Dclippy::complexity \
> +                           -Dclippy::perf \
> +                           -Dclippy::let_unit_value -Dclippy::mut_mut \
> +                           -Dclippy::needless_bitwise_bool \
> +                           -Dclippy::needless_continue \
> +                           -Wclippy::dbg_macro

Hi Miguel,

I tried enabling rust support in the gcc builds I provide at
https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/arm64/12.1.0/
to make this more accessible, but it appears that the command line
options here are not portable:

 /home/arnd/cross/x86_64/gcc-12.1.0+rust-nolibc/x86_64-linux/bin/x86_64-linux-gccrs
--edition=2021 -Zbinary_dep_depinfo=y -Dunsafe_op_in_unsafe_fn
-Drust_2018_idioms -Dunreachable_pub -Dnon_ascii_idents -Wmissing_docs
-Drustdoc::missing_crate_level_docs -Dclippy::correctness
-Dclippy::style -Dclippy::suspicious -Dclippy::complexity
-Dclippy::perf -Dclippy::let_unit_value -Dclippy::mut_mut
-Dclippy::needless_bitwise_bool -Dclippy::needless_continue
-Wclippy::dbg_macro -O -Cstrip=debuginfo -Zallow-features=
--emit=dep-info,link --out-dir=scripts/
/git/arm-soc/scripts/generate_rust_target.rs; mv
scripts/generate_rust_target.d scripts/.generate_rust_target.d; sed -i
'/^#/d' scripts/.generate_rust_target.d
x86_64-linux-gccrs: error: unrecognized command-line option
'--edition=2021'; did you mean '-frust-edition=2021'?
x86_64-linux-gccrs: error: unrecognized command-line option
'-Zbinary_dep_depinfo=y'
x86_64-linux-gccrs: error: unrecognized command-line option
'-Wmissing_docs'; did you mean '-Wmissing-braces'?
x86_64-linux-gccrs: error: unrecognized command-line option
'-Wclippy::dbg_macro'
x86_64-linux-gccrs: error: unrecognized command-line option '-Cstrip=debuginfo'
x86_64-linux-gccrs: error: unrecognized command-line option '-Zallow-features='
x86_64-linux-gccrs: error: unrecognized command-line option
'--emit=dep-info,link'
x86_64-linux-gccrs: error: unrecognized command-line option '--out-dir=scripts/'
make[3]: *** [/git/arm-soc/scripts/Makefile.host:157:
scripts/generate_rust_target] Error 1

I guess nobody has tried this so far. Would you think that fixing this is only
a matter for fixing the build system to pass the correct flags depending on the
compiler, or is this broken in a more fundamental way?

         Arnd