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;
From:   Miguel Ojeda <ojeda@kernel.org>
To:     Masahiro Yamada <masahiroy@kernel.org>,
        Miguel Ojeda <ojeda@kernel.org>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Alex Gaynor <alex.gaynor@gmail.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Alice Ryhl <aliceryhl@google.com>,
        Andreas Hindborg <nmi@metaspace.dk>,
        linux-kbuild@vger.kernel.org, rust-for-linux@vger.kernel.org,
        linux-kernel@vger.kernel.org, patches@lists.linux.dev
Subject: [PATCH v2 03/11] docs: rust: add paragraph about finding a suitable `libclang`
Date:   Fri, 16 Jun 2023 02:16:23 +0200
Message-ID: <20230616001631.463536-4-ojeda@kernel.org>
In-Reply-To: <20230616001631.463536-1-ojeda@kernel.org>
References: <20230616001631.463536-1-ojeda@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Sometimes users need to tweak the finding process of `libclang`
for `bindgen` via the `clang-sys`-provided environment variables.

Thus add a paragraph to the setting up guide, including a reference
to `clang-sys`'s relevant documentation.

Link: https://lore.kernel.org/rust-for-linux/CAKwvOdm5JT4wbdQQYuW+RT07rCi6whGBM2iUAyg8A1CmLXG6Nw@mail.gmail.com/
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 Documentation/rust/quick-start.rst | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Documentation/rust/quick-start.rst b/Documentation/rust/quick-start.rst
index 13b7744b1e27..a635be69e062 100644
--- a/Documentation/rust/quick-start.rst
+++ b/Documentation/rust/quick-start.rst
@@ -100,6 +100,23 @@ Install it via (note that this will download and build the tool from source)::
 
 	cargo install --locked --version $(scripts/min-tool-version.sh bindgen) bindgen
 
+``bindgen`` needs to find a suitable ``libclang`` in order to work. If it is
+not found (or a different ``libclang`` than the one found should be used),
+the process can be tweaked using the environment variables understood by
+``clang-sys`` (the Rust bindings crate that ``bindgen`` uses to access
+``libclang``):
+
+* ``LLVM_CONFIG_PATH`` can be pointed to an ``llvm-config`` executable.
+
+* Or ``LIBCLANG_PATH`` can be pointed to a ``libclang`` shared library
+  or to the directory containing it.
+
+* Or ``CLANG_PATH`` can be pointed to a ``clang`` executable.
+
+For details, please see ``clang-sys``'s documentation at:
+
+	https://github.com/KyleMayes/clang-sys#environment-variables
+
 
 Requirements: Developing
 ------------------------
-- 
2.41.0