From:   Asahi Lina <lina@asahilina.net>
Date:   Fri, 24 Feb 2023 17:09:47 +0900
Subject: [PATCH] rust: Enable the new_uninit feature for kernel and driver
 crates
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Message-Id: <20230224-rust-new_uninit-v1-1-c951443d9e26@asahilina.net>
To:     Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@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>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>
Cc:     rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kbuild@vger.kernel.org, asahi@lists.linux.dev,
        Asahi Lina <lina@asahilina.net>
Precedence: bulk

The unstable new_uninit feature enables various library APIs to create
uninitialized containers, such as `Box::assume_init()`. This is
necessary to build abstractions that directly initialize memory at the
target location, instead of doing copies through the stack.

Will be used by the DRM scheduler abstraction in the kernel crate, and
by field-wise initialization (e.g. using `place!()` or a future
replacement macro which may itself live in `kernel`) in driver crates.

See [1] [2] [3] for background information.

[1] https://github.com/Rust-for-Linux/linux/issues/879
[2] https://github.com/Rust-for-Linux/linux/issues/2
[3] https://github.com/rust-lang/rust/issues/63291

Signed-off-by: Asahi Lina <lina@asahilina.net>
---
 rust/kernel/lib.rs     | 1 +
 scripts/Makefile.build | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 223564f9f0cc..1118cd3e0b5f 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -17,6 +17,7 @@
 #![feature(core_ffi_c)]
 #![feature(dispatch_from_dyn)]
 #![feature(generic_associated_types)]
+#![feature(new_uninit)]
 #![feature(receiver_trait)]
 #![feature(unsize)]
 
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index a0d5c6cca76d..0f637e1ca8dc 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
 # Compile Rust sources (.rs)
 # ---------------------------------------------------------------------------
 
-rust_allowed_features := core_ffi_c
+rust_allowed_features := core_ffi_c,new_uninit
 
 rust_common_cmd = \
 	RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \

---
base-commit: 83f978b63fa7ad474ca22d7e2772c5988101c9bd
change-id: 20230224-rust-new_uninit-a575d34987c3

Thank you,
~~ Lina