From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PQ+ZyJqy" Received: from mail-oi1-x22a.google.com (mail-oi1-x22a.google.com [IPv6:2607:f8b0:4864:20::22a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4C4CD5B; Fri, 8 Dec 2023 23:24:50 -0800 (PST) Received: by mail-oi1-x22a.google.com with SMTP id 5614622812f47-3b9e7f4a0d7so1159464b6e.1; Fri, 08 Dec 2023 23:24:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1702106690; x=1702711490; darn=vger.kernel.org; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=gA6npP4B/1h8Lv3vDYT50LP0HFiir56XGpjRhpKMK7Q=; b=PQ+ZyJqyI3alLnQm4J1OcJ0vHwSxcnkBAjQeJqtr8LtTYWT8i06FAtkBo7t8zGWsb1 7VW6PvbiN4VKQfJtaUpXvcJrhk1NHb0IEAeT5VhpJANvzKU81p8pvoRK556SNRs37psG HaU/WKxVXtepGBpZ9hVx96mTUxLDhglwx8hGNQB4GEdq9K23x0VP8d6HbWZ2/eQlDHtY mVU/jD4c22mSKVhZqmXOX4TLBvJqP0k5toS+s7PD1HY/AJA7Zb5sG5O6TgSlWLwzTWi9 hGoVsbX6RkPHMUXBnfwtVV6Y36mibl2gY4e3zcqRTHKJey1ldw2SyrHCvnbYnNIafM+s +0kA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702106690; x=1702711490; h=to:references:message-id:content-transfer-encoding:cc:date :in-reply-to:from:subject:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=gA6npP4B/1h8Lv3vDYT50LP0HFiir56XGpjRhpKMK7Q=; b=eD44ILXzitgfn1PCUg5BgSlT+B+nhDLW15d/pBdXAaEh9CwCsqC7nC6ciHFIfnhrpM 4BS7howJXDs5aFJ1gkl4g02T4Z7KiS7CthpmDAzKQj5U2in2SIZ3l1BFWNfi3Mj7CORa 0ObAlxmrHve3NZ/o8l7tNG8/0ChVCQQFrwlJF1e6lKh4ig/HgiPnf9+lesAWyyopCO5r IN2rJTyZG/q7phAzUGVNEEsX9Z1MnBvd/jRrGeHkTWUzj3CumO11T4/8i7tm5t28ls1c 3q6q9mJa0rl4CB3uuspVFAhTegI33cFQR0rq36/wnCYH+6Fal4joW7XP+r9n/llSPwpm XcMw== X-Gm-Message-State: AOJu0Yyomo21hq7zDwgiC/3z4NbMGBPvthubDmQZMh9Yuk+ltam5Ea48 3O6eBuFDz3MqGe0Og9k92es= X-Google-Smtp-Source: AGHT+IGYs36YJSRK1ZVmaBkJb+Iy1NEnIFrzQTgWan5NjNjvr9PNhQmEwveSqekX+ik6sq3a4cawzA== X-Received: by 2002:a05:6808:120c:b0:3b8:b063:505e with SMTP id a12-20020a056808120c00b003b8b063505emr1458196oil.95.1702106689952; Fri, 08 Dec 2023 23:24:49 -0800 (PST) Received: from smtpclient.apple ([2601:647:4b00:6db0:219a:6f4c:ab6a:436d]) by smtp.gmail.com with ESMTPSA id q28-20020a056a0002bc00b006ce350d946csm2682652pfs.41.2023.12.08.23.24.47 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 08 Dec 2023 23:24:49 -0800 (PST) Content-Type: text/plain; charset=utf-8 Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.300.61.1.2\)) Subject: Re: [PATCH 5/7] rust: file: add `Kuid` wrapper From: comex In-Reply-To: Date: Fri, 8 Dec 2023 23:24:35 -0800 Cc: Christian Brauner , Peter Zijlstra , Alice Ryhl , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alexander Viro , Greg Kroah-Hartman , =?utf-8?Q?Arve_Hj=C3=B8nnev=C3=A5g?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Carlos Llamas , Suren Baghdasaryan , Dan Williams , Kees Cook , Matthew Wilcox , Thomas Gleixner , Daniel Xu , linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-fsdevel@vger.kernel.org, Nick Desaulniers Content-Transfer-Encoding: quoted-printable Message-Id: <4364B468-E0DD-4419-B26E-13B9C3F53F7C@gmail.com> References: <20231129-alice-file-v1-0-f81afe8c7261@google.com> <20231129-alice-file-v1-5-f81afe8c7261@google.com> <20231129-etappen-knapp-08e2e3af539f@brauner> <20231129164815.GI23596@noisy.programming.kicks-ass.net> <20231130-wohle-einfuhr-1708e9c3e596@brauner> To: Miguel Ojeda X-Mailer: Apple Mail (2.3774.300.61.1.2) On Dec 8, 2023, at 8:19=E2=80=AFAM, Miguel Ojeda = wrote: >=20 > If LLVM folks think LLVM-wise nothing will break, then we are happy to > go ahead with that (since it also solves the performance side), but it > would be nice to know if it will always be OK to build like that, i.e. > I think Andreas actually tried it and it seemed to work and boot, but > the worry is whether there is something subtle that could have bad > codegen in the future. One potential issue is incompatibility between the LLVM versions used by = rustc, Clang, and LLD. At minimum, whichever tool is reading bitcode = (LLD in my example) should have an LLVM version >=3D that of the tools = producing bitcode, since newer LLVM versions can read older bitcode but = not vice versa. But ideally the tools would all just be linked against = the same copy of LLVM. If you=E2=80=99re getting your tools from a distro, then that may = already be true for you. But if you=E2=80=99re using upstream rustc = binaries, those are built against a custom branch of LLVM, which is = based on upstream release versions but adds a handful of patches [1]; by = policy, those patches can include cherry-picks of miscompilation fixes = that are upstream but haven=E2=80=99t made it into a release yet [2]. = Upstream rustc binaries are accompanied by a copy of LLD linked against = the same LLVM library, named rust-lld, but there=E2=80=99s no = corresponding copy of Clang [3]. I=E2=80=99d say that agreement between = rustc and LLD is the most important thing, but it would be nice if = they'd make a matching Clang available through rustup. [1] = https://github.com/llvm/llvm-project/compare/release/17.x...rust-lang:llvm= -project:rustc/17.0-2023-09-19 [2] = https://rustc-dev-guide.rust-lang.org/backend/updating-llvm.html#bugfix-up= dates [3] https://github.com/rust-lang/rust/issues/56371=