From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A75DC43461 for ; Fri, 16 Apr 2021 06:04:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3D896117A for ; Fri, 16 Apr 2021 06:04:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237264AbhDPGFR (ORCPT ); Fri, 16 Apr 2021 02:05:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234979AbhDPGFQ (ORCPT ); Fri, 16 Apr 2021 02:05:16 -0400 Received: from mail-lf1-x134.google.com (mail-lf1-x134.google.com [IPv6:2a00:1450:4864:20::134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC69CC06175F for ; Thu, 15 Apr 2021 23:04:50 -0700 (PDT) Received: by mail-lf1-x134.google.com with SMTP id f41so19567023lfv.8 for ; Thu, 15 Apr 2021 23:04:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=gbzaa2Ai7xXdaJk+SuOzDr1sDQqCY9sqWL6R/1Zrh+s=; b=W5/QWZWFFaSWg9idKZ6DJEpPmhh/eOS3XCiS0GJpjJR7c/9hO/bPRnbhDx6fcqOh/0 sp9nz3xawBALOHCXGcN4jIih6Lo7LRUhWSYjVKt/IE7M5QZMCikdUSMKXXJqXnNorxIu UcotZdbyz0htz+FRuAF9BYmaG3K/gWMFAT/A8/JmQBFrNNVdGLgxB72JzOcS3dWuBrUO pLLR3MAXjECLXZHF0eu89BJvQwappXx3P0EcpPXDjPCJULvqxF+y1iSxNPQzfc3EiG4c rSb/0coU8nEO5IvdaN3SjfYFjNy5PzO32XHT/eoBVhUpxXlkT2FrApLCrpZqzbcHuazj 0Naw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=gbzaa2Ai7xXdaJk+SuOzDr1sDQqCY9sqWL6R/1Zrh+s=; b=omqH4okdM3wWtsFFhLa/eHHo2lap4bVf9NzdVAqSMUBuT4qcyKD0lzviN/ohFgauYO 676gKc3FfB+mun48N4Tsgsw1f1AwMym+2HMhxKcqmDof0Dk9UQBwYdJDv0a5mws59qNm Hq90Hx2bjjUDgxpoqesVtB/a9nHyc/H284GGStUwM02m4/ygZilbJ6pFfYcG/66nkhNh jtagyaH4D3tKIinbtXpV8dXx8cQLzyh9Qkw1k1C2OaNzya50pmD+r9cUve0+qaRD4PWX 9Rs36KfFnq8/Ds2Gljcle3kRIlGQD9/9PYGlb3Bocac/ryNQNMK6U2Y5QRKp3HyL/0jC ScOw== X-Gm-Message-State: AOAM531bti66VRG50ryFEWYN/WSD3Q30gmkAPOKKVUq724AQSIKX/Cua HVxWGWIRqbvYyIBsDeawaIYWlxjTX2TtTD5eCVnVBA== X-Google-Smtp-Source: ABdhPJzd3Uifx8wPh8+Ukv5wC6+mAKF4pnOLfbn/l4Zr9Mzj0XiDdg2h8UGLElnlq21TU6eWm2HsUZh+V10t5NGgiSg= X-Received: by 2002:a19:ac09:: with SMTP id g9mr1821239lfc.547.1618553088788; Thu, 15 Apr 2021 23:04:48 -0700 (PDT) MIME-Version: 1.0 References: <20210414184604.23473-1-ojeda@kernel.org> In-Reply-To: From: Nick Desaulniers Date: Thu, 15 Apr 2021 23:04:37 -0700 Message-ID: Subject: Re: [PATCH 00/13] [RFC] Rust support To: Boqun Feng Cc: Peter Zijlstra , ojeda@kernel.org, Linus Torvalds , Greg Kroah-Hartman , rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Alan Stern , Andrea Parri , Will Deacon , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , "Paul E. McKenney" , Akira Yokosawa , Daniel Lustig , Joel Fernandes , Josh Triplett , Wedson Almeida Filho Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, Apr 15, 2021 at 9:27 PM Boqun Feng wrote: > > [Copy LKMM people, Josh, Nick and Wedson] > > On Thu, Apr 15, 2021 at 08:58:16PM +0200, Peter Zijlstra wrote: > > On Wed, Apr 14, 2021 at 08:45:51PM +0200, ojeda@kernel.org wrote: > > > > > Rust is a systems programming language that brings several key > > > advantages over C in the context of the Linux kernel: > > > > > > - No undefined behavior in the safe subset (when unsafe code is > > > sound), including memory safety and the absence of data races. > > > > And yet I see not a single mention of the Rust Memory Model and how it > > aligns (or not) with the LKMM. The C11 memory model for example is a > > really poor fit for LKMM. > > > > I think Rust currently uses C11 memory model as per: > > https://doc.rust-lang.org/nomicon/atomics.html > > , also I guess another reason that they pick C11 memory model is because > LLVM has the support by default. > > But I think the Rust Community still wants to have a good memory model, > and they are open to any kind of suggestion and input. I think we (LKMM > people) should really get involved, because the recent discussion on > RISC-V's atomics shows that if we didn't people might get a "broken" > design because they thought C11 memory model is good enough: > > https://lore.kernel.org/lkml/YGyZPCxJYGOvqYZQ@boqun-archlinux/ > > And the benefits are mutual: a) Linux Kernel Memory Model (LKMM) is > defined by combining the requirements of developers and the behavior of > hardwares, it's pratical and can be a very good input for memory model > designing in Rust; b) Once Rust has a better memory model, the compiler > technologies whatever Rust compilers use to suppor the memory model can > be adopted to C compilers and we can get that part for free. Yes, I agree; I think that's a very good approach. Avoiding the ISO WG14 is interesting; at least the merits could be debated in the public and not behind closed doors. > > At least I personally is very intereted to help Rust on a complete and > pratical memory model ;-) > > Josh, I think it's good if we can connect to the people working on Rust > memoryg model, I think the right person is Ralf Jung and the right place > is https://github.com/rust-lang/unsafe-code-guidelines, but you > cerntainly know better than me ;-) Or maybe we can use Rust-for-Linux or > linux-toolchains list to discuss. > > [...] > > > - Boqun Feng is working hard on the different options for > > > threading abstractions and has reviewed most of the `sync` PRs. > > > > Boqun, I know you're familiar with LKMM, can you please talk about how > > Rust does things and how it interacts? > > As Wedson said in the other email, currently there is no code requiring > synchronization between C side and Rust side, so we are currently fine. > But in the longer term, we need to teach Rust memory model about the > "design patterns" used in Linux kernel for parallel programming. > > What I have been doing so far is reviewing patches which have memory > orderings in Rust-for-Linux project, try to make sure we don't include > memory ordering bugs for the beginning. > > Regards, > Boqun -- Thanks, ~Nick Desaulniers