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Tue, 16 Dec 2025 06:41:54 -0800 (PST) Message-ID: <0705db10-3cbb-4958-a116-112457f9af6c@gmail.com> Date: Tue, 16 Dec 2025 15:41:52 +0100 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: ARMv7 Linux + Rust doesn't boot when compiling with only LLVM=1 To: Rudraksha Gupta , stable@vger.kernel.org, regressions@lists.linux.dev, rust-for-linux@vger.kernel.org, Miguel Ojeda , llvm@lists.linux.dev, Linux ARM Cc: =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alex Gaynor , Boqun Feng , Gary Guo , Andreas Hindborg , Alice Ryhl , Danilo Krummrich , Trevor Gross , Benno Lossin References: <1286af8e-f908-45db-af7c-d9c5d592abfd@gmail.com> Content-Language: en-US, de-DE From: Christian Schrefl In-Reply-To: <1286af8e-f908-45db-af7c-d9c5d592abfd@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 12/14/25 12:54 AM, Rudraksha Gupta wrote: > Hello all, > > > I have the following problem: https://gitlab.postmarketos.org/postmarketOS/pmbootstrap/-/issues/2635 > > > In short, what is happening is the following: > > > - The kernel boots and outputs via UART when I build the kernel with the following: > > make LLVM=1 ARCH="$arm" CC="${CC:-gcc}" > > > - The kernel doesn't boot and there is no output via UART when I build the kernel with the following: > > make LLVM=1 ARCH="$arm" > > > The only difference being: CC="${CC:-gcc}". Is this expected? I think this was present in the Linux kernel ever since Rust was enabled for ARMv7, and I never encountered it because postmarketOS was originally building the first way. I've managed to the get the build setup for qemu-armv7. For some reason I could not get past the initrd even on kernels that are supposed to work, but I think that is unrelated (and not a kernel issue). On the linux-next kernel I didn't get any output on the console from qemu so I think I've reproduced the issue. Changing CONFIG_RUST=n did not change the behavior. So I this is almost certainly a LLVM/clang issue and not a Rust issue. I'll try to do a bit more digging, but I'm not sure how much I'll get done. Adding the LLVM and ARM lists to this conversation. Cheers, Christian