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Thu, 26 Mar 2026 03:10:11 -0700 (PDT) Date: Thu, 26 Mar 2026 10:10:10 +0000 In-Reply-To: Mime-Version: 1.0 References: <20260322192159.88138-1-ojeda@kernel.org> <20260323000327.111235-1-ojeda@kernel.org> Message-ID: Subject: Re: Re: [PATCH v2 0/3] Inline helpers into Rust without full LTO From: Alice Ryhl To: "Russell King (Oracle)" Cc: Miguel Ojeda , a.hindborg@kernel.org, acourbot@nvidia.com, akpm@linux-foundation.org, anton.ivanov@cambridgegreys.com, bjorn3_gh@protonmail.com, boqun.feng@gmail.com, dakr@kernel.org, david@davidgow.net, gary@garyguo.net, johannes@sipsolutions.net, justinstitt@google.com, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-um@lists.infradead.org, llvm@lists.linux.dev, lossin@kernel.org, mark.rutland@arm.com, mmaurer@google.com, morbo@google.com, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, nicolas.schier@linux.dev, nsc@kernel.org, peterz@infradead.org, richard@nod.at, rust-for-linux@vger.kernel.org, tmgross@umich.edu, urezki@gmail.com, will@kernel.org Content-Type: text/plain; charset="utf-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260326_031014_783620_6455C228 X-CRM114-Status: GOOD ( 22.00 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Mar 23, 2026 at 10:03:26AM +0000, Russell King (Oracle) wrote: > On Mon, Mar 23, 2026 at 01:03:27AM +0100, Miguel Ojeda wrote: > > On Sun, 22 Mar 2026 20:21:59 +0100 Miguel Ojeda wrote: > > > > > > On the other hand, regardless of whether we fix this (and another > > > issue in a separate email found thanks to the UML build), we could > > > instead add `depends on` listing explicitly the architectures where > > > this is going to be actually tested. That way maintainers can decide > > > whether they want to support it when they are ready. Thoughts? > > > > Another one for arm 32-bit: > > > > LD .tmp_vmlinux1 > > ld.lld: error: undefined symbol: __aeabi_read_tp > > >>> referenced by uaccess.rs:349 (rust/kernel/uaccess.rs:349) > > >>> samples/rust/rust_misc_device.o:(::ioctl) in archive vmlinux.a > > >>> referenced by uaccess.rs:543 (rust/kernel/uaccess.rs:543) > > >>> samples/rust/rust_misc_device.o:(::ioctl) in archive vmlinux.a > > >>> referenced by uaccess.rs:543 (rust/kernel/uaccess.rs:543) > > >>> drivers/android/binder/rust_binder_main.o:(rust_binder_main::rust_binder_ioctl) in archive vmlinux.a > > >>> referenced 36 more times > > Why is Rust generating code for userspace thread accessors for kernel > space, where userspace threads are meaningless. This is totally wrong. > The kernel must not reference __aeabi_read_tp(). > > Note: I know nothing about Rust, but I know enough to say the above is > pointing to a fundamental issue in Rust for 32-bit ARM. I noticed that the Makefile currently uses the arm-unknown-linux-gnueabi target. It should probably not be -linux target to avoid this? Probably it should just be armv7a-none-eabi, right? We gate HAVE_RUST on CPU_32v7, so we should not need to consider the other variants. Alice