Re: [PATCH 15/19] Kbuild: add Rust support

From: Wedson Almeida Filho <wedsonaf@google.com>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	linux-kbuild@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	rust-for-linux@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, Alex Gaynor <alex.gaynor@gmail.com>,
	Finn Behrens <me@kloenk.de>,
	Adam Bratschi-Kaye <ark.email@gmail.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Sven Van Asbroeck <thesven73@gmail.com>,
	Gary Guo <gary@garyguo.net>,
	Boris-Chengbiao Zhou <bobo1239@web.de>,
	Boqun Feng <boqun.feng@gmail.com>,
	Douglas Su <d0u9.su@outlook.com>,
	Dariusz Sosnowski <dsosnowski@dsosnowski.pl>,
	Antonio Terceiro <antonio.terceiro@linaro.org>,
	Daniel Xu <dxu@dxuuu.xyz>
Subject: Re: [PATCH 15/19] Kbuild: add Rust support
Date: Tue, 7 Dec 2021 23:25:36 +0000	[thread overview]
Message-ID: <CAMKQLNJKumnucRHttHFN0cMK_g6kCJ7o0ev_3_RJsmPqbjo08g@mail.gmail.com> (raw)
In-Reply-To: <CAKwvOdk9VNenJJN5HnPpGgsHT+OsRsgPGSesQgqMP2aLPWy0NQ@mail.gmail.com>

On Tue, 7 Dec 2021 at 23:21, Nick Desaulniers <ndesaulniers@google.com> wrote:
>
> On Tue, Dec 7, 2021 at 2:45 PM Nick Desaulniers <ndesaulniers@google.com> wrote:
> >
> > On Mon, Dec 6, 2021 at 6:07 AM Miguel Ojeda <ojeda@kernel.org> wrote:
> > >
> >
> > ... snip ...
> >
> > Miguel and team,
> > I'm happy to see progress here! Just some quick notes after a first pass.
> >
> > Testing this series applied on mainline, I see:
> > $ make LLVM=1 -j72 defconfig
> > $ grep RUST .config
> > CONFIG_HAS_RUST=y
> > CONFIG_RUSTC_VERSION=14000
> > # CONFIG_RUST is not set
> > ...
> > $ make LLVM=1 -j72 menuconfig
> > # enable CONFIG_RUST
> > $ make LLVM=1
> > ...
> >   CALL    scripts/checksyscalls.sh
> > error: @path is unstable - use -Z unstable-options to enable its use
> >
> > error: @path is unstable - use -Z unstable-options to enable its use
> > $ rustc --version
> > rustc 1.40.0 (73528e339 2019-12-16)
> >
> > Can we update some Kconfig checks to fix that?
>
> After now reading though the Documentation/ patch:
>
> $ rustup update
> $ rustc --version
> rustc 1.57.0 (f1edd0429 2021-11-29)
> $ make LLVM=1 -j72
> ...
> make[1]: *** No rule to make target
> '/usr/local/google/home/ndesaulniers/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/lib.rs',
> needed by 'rust/core.o'.  Stop.

Can you run `rustup component add rust-src`?

When we change the compiler version, we need to install the source
code for `core` for the new version. (We'll update the documentation
to reflect that.)

> Maybe I'm holding it wrong, let me reread the Documentation/ again.
>
> I still think CONFIG_RUST shouldn't be selectable unless
> CONFIG_RUSTC_VERSION is either a blessed version, or above some
> minimal value (like we do for CONFIG_GCC_VERSION, CONFIG_LD_VERSION,
> CONFIG_CLANG_VERSION, LLD_VERSION, etc).
>
> Also, it looks like I don't have bindgen installed. Anything we can do
> there to help the developer out, as in informing them that it's
> necessary perhaps via a Kconfig check? I don't think I should be able
> to select CONFIG_RUST if I don't have bindgen installed. (Same comment
> about version check probably applies, too).  Installing bindgen
> doesn't change the error I'm observing above though.
> --
> Thanks,
> ~Nick Desaulniers