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References: <20240217002638.57373-1-ojeda@kernel.org> <20240217002638.57373-2-ojeda@kernel.org>
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From: Alice Ryhl <aliceryhl@google.com>
Date: Mon, 19 Feb 2024 10:09:09 +0100
Message-ID: <CAH5fLghAC7yJLzH1K4Jv10QggnG5eHacGTJ8mxgO5neH7YR+EA@mail.gmail.com>
Subject: Re: [PATCH 2/2] rust: upgrade to Rust 1.76.0
To: Miguel Ojeda <ojeda@kernel.org>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>, Alex Gaynor <alex.gaynor@gmail.com>, 
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>, 
	=?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, 
	Benno Lossin <benno.lossin@proton.me>, Andreas Hindborg <a.hindborg@samsung.com>, 
	Masahiro Yamada <masahiroy@kernel.org>, linux-kbuild@vger.kernel.org, 
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, 
	patches@lists.linux.dev
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On Sat, Feb 17, 2024 at 1:27=E2=80=AFAM Miguel Ojeda <ojeda@kernel.org> wro=
te:
>
> This is the next upgrade to the Rust toolchain, from 1.75.0 to 1.76.0
> (i.e. the latest) [1].
>
> See the upgrade policy [2] and the comments on the first upgrade in
> commit 3ed03f4da06e ("rust: upgrade to Rust 1.68.2").
>
> # Unstable features
>
> No unstable features that we use were stabilized in Rust 1.76.0.
>
> The only unstable features allowed to be used outside the `kernel` crate
> are still `new_uninit,offset_of`, though other code to be upstreamed
> may increase the list.
>
> Please see [3] for details.
>
> # Required changes
>
> `rustc` (and others) now warns when it cannot connect to the Make
> jobserver, thus mark those invocations as recursive as needed. Please
> see the previous commit for details.
>
> # Other changes
>
> Rust 1.76.0 does not emit the `.debug_pub{names,types}` sections anymore
> for DWARFv4 [4][5]. For instance, in the uncompressed debug info case,
> this debug information took:
>
>     samples/rust/rust_minimal.o   ~64 KiB (~18% of total object size)
>     rust/kernel.o                 ~92 KiB (~15%)
>     rust/core.o                  ~114 KiB ( ~5%)
>
> In the compressed debug info (zlib) case:
>
>     samples/rust/rust_minimal.o   ~11 KiB (~6%)
>     rust/kernel.o                 ~17 KiB (~5%)
>     rust/core.o                   ~21 KiB (~1.5%)
>
> In addition, the `rustc_codegen_gcc` backend now does not emit the
> `.eh_frame` section when compiling under `-Cpanic=3Dabort` [6], thus
> removing the need for the patch in the CI to compile the kernel [7].
> Moreover, it also now emits the `.comment` section too [6].
>
> # `alloc` upgrade and reviewing

[...]

> Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1=
760-2024-02-08 [1]
> Link: https://rust-for-linux.com/rust-version-policy [2]
> Link: https://github.com/Rust-for-Linux/linux/issues/2 [3]
> Link: https://github.com/rust-lang/compiler-team/issues/688 [4]
> Link: https://github.com/rust-lang/rust/pull/117962 [5]
> Link: https://github.com/rust-lang/rust/pull/118068 [6]
> Link: https://github.com/Rust-for-Linux/ci-rustc_codegen_gcc [7]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>