September 2025 - kernelnewbies@kernelnewbies.org

Rust: how to implement file_operations for a misc device?
by Fabio Nov. 20, 2025

Nov. 20, 2025

Hello, brand-new kernel newbie here. I'm interested in the Rust side of the kernel. To get acquainted, I'm following the Linux Driver Development book, 3rd edition, also integrating it with modern documentation and best practices (or at least I hope so). I'm developing the scull module on top of the `kernel::miscdevice::MiscDevice` trait. Where I'm stuck at is the lack of the `kernel::file::Operations` trait [1], that most online resources refer to. I need such trait to implement read and write operations for the misc device. AFAIU, this trait used to exist but it's no longer in the mainline codebase [2]. Also, `kernel::miscdevice::MiscdeviceVTable` is private inside the miscdevice module, so there's no way I can somehow extend it. Is there any workaround for what I want to achieve, or is ioctl the only allowed interface to misc devices in Rust? Thank you, Fabio. [^1]: https://rust-for-linux.github.io/docs/kernel/file/trait.Operations.html [^2]: https://rust.docs.kernel.org/kernel/fs/index.html

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Existing patches of similar content
by Torin Carey Sept. 15, 2025

Sept. 15, 2025

Hi KernelNewbies, Apologies if this is a stupid question. I was finishing up on a patch to add a new (fairly small) feature to an existing driver. While looking at the archives for the relevant mailing list, I noticed another contributor had submitted a patch to add the exact same feature just under a year ago, but the thread seems to have gone stale. I believe there are some bits that were missing from this patch in terms of correctness. What's the usual etiquette to approach this situation? I could: 1. submit my patch for review anyway; or 2. resurrect this thread providing a review for it along with the additions I think might be necessary; or 3. a combination of both? --- Torin

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(no subject)
by Daniel Sept. 1, 2025

Sept. 1, 2025

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