[PATCH] rust: Suppress searching builtin sysroot

From: Matthew Maurer <mmaurer@google.com>
To: Jamie.Cunliffe@arm.com, Miguel Ojeda <ojeda@kernel.org>,
	 Alex Gaynor <alex.gaynor@gmail.com>,
	Wedson Almeida Filho <wedsonaf@gmail.com>,
	 Masahiro Yamada <masahiroy@kernel.org>
Cc: will@kernel.org, "Matthew Maurer" <mmaurer@google.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Benno Lossin" <benno.lossin@proton.me>,
	"Andreas Hindborg" <a.hindborg@samsung.com>,
	"Alice Ryhl" <aliceryhl@google.com>,
	"Nathan Chancellor" <nathan@kernel.org>,
	"Nick Desaulniers" <ndesaulniers@google.com>,
	"Nicolas Schier" <nicolas@fjasle.eu>,
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-kbuild@vger.kernel.org
Subject: [PATCH] rust: Suppress searching builtin sysroot
Date: Tue, 31 Oct 2023 20:10:14 +0000	[thread overview]
Message-ID: <20231031201752.1189213-1-mmaurer@google.com> (raw)

By default, if Rust is passed `--target=foo` rather than a target.json
file, it will infer a default sysroot if that component is installed. As
the proposed aarch64 support uses `aarch64-unknown-none` rather than a
target.json file, this is needed to prevent rustc from being confused
between the custom kernel sysroot and the pre-installed one.

Signed-off-by: Matthew Maurer <mmaurer@google.com>
---

This patch is prompted by the issue I encountered at
https://lore.kernel.org/all/CAGSQo01pOixiPXkW867h4vPUaAjtKtHGKhkV-rpifJvKxAf4Ww@mail.gmail.com/
but should be generically more hermetic even if we don't end up landing
that patch.

 rust/Makefile          | 1 +
 scripts/Makefile.build | 1 +
 2 files changed, 2 insertions(+)

diff --git a/rust/Makefile b/rust/Makefile
index a27f35f924ec..0403e88e19fd 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -400,6 +400,7 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
 		--emit=metadata=$(dir $@)$(patsubst %.o,lib%.rmeta,$(notdir $@)) \
 		--crate-type rlib -L$(objtree)/$(obj) \
 		--crate-name $(patsubst %.o,%,$(notdir $@)) $< \
+		--sysroot=/dev/null \
 	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@)
 
 rust-analyzer:
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 82e3fb19fdaf..6e4ee513cc3c 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -275,6 +275,7 @@ rust_common_cmd = \
 	--extern alloc --extern kernel \
 	--crate-type rlib -L $(objtree)/rust/ \
 	--crate-name $(basename $(notdir $@)) \
+	--sysroot=/dev/null \
 	--out-dir $(dir $@) --emit=dep-info=$(depfile)
 
 # `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit
-- 
2.42.0.820.g83a721a137-goog

