From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5F05D1D14FF; Fri, 28 Feb 2025 21:29:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740778182; cv=none; b=e6aBsN4W5DVeyID3j73oJoNopeLIN+vXMnjSSGHL7Ls8+wQPEc6TzipZ8wfsuTlyHUtaDAEWO7D+WRRBzh3JE285kTkPBXSuUdP2Q1litbZ5fOANPCIbnQ2W9ggqMZs4XsQzMCEyLKCLx1zgHAacr3+FoBqn59S3FBvCqtxrCLc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740778182; c=relaxed/simple; bh=WpiVu7G/gcbEeYsk0cZWhzU9IoiNFSi9tQN7+E70E/U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ACMo9s1DpG3LsTMaIJI+pnDMHiyi10TFNtLItNEzw07ds1oryChW+EnHKHtvVlRW8VjunL/0MooJBK5KVPOBCPriklQzo8V9dF7bcudI+7f4NGBd5SUYfiBHMn8L+uD2CSiwf2+0SpjmJakKxo+tVNktm1mfDhDsC5/mkXf54lA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KCqTnMgV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KCqTnMgV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D44D1C4CED6; Fri, 28 Feb 2025 21:29:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740778181; bh=WpiVu7G/gcbEeYsk0cZWhzU9IoiNFSi9tQN7+E70E/U=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=KCqTnMgVZuiubKIq3Pe73kKLpBSoxSEgapK1uRgJAzodbAGBKhbwMI8D4DxZCWcVq Ia3/J6lTtOoBlZLrObo6+sVsrT/wKVRvx0vuMYoTk9tDVO6MdaPZZgqdQ++ZgLuWxV ownqmVOkfsk8PMk3VSzOe9Mjc4uy853/C1YSoNlD3Nx52WCPNUQu/W9GY6h17JgBAl OktAqIBVcGcgLCqFOM+mJQPeV2r8pZLN19uK2vqVxyZyiLWUHK58gJ2z+3/4nV1Hl+ sRqCW15aNNpk05wpqCgW+HhaJY9n7K/wvYRni+/KwfUxrbIwjezsw0DYjCJeG+iy6X IvMqLoudr5DmA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 7BE1DCE0DEB; Fri, 28 Feb 2025 13:29:41 -0800 (PST) Date: Fri, 28 Feb 2025 13:29:41 -0800 From: "Paul E. McKenney" To: Steven Rostedt Cc: David Laight , Linus Torvalds , Martin Uecker , Ralf Jung , Alice Ryhl , Ventura Jack , Kent Overstreet , Gary Guo , airlied@gmail.com, boqun.feng@gmail.com, ej@inai.de, gregkh@linuxfoundation.org, hch@infradead.org, hpa@zytor.com, ksummit@lists.linux.dev, linux-kernel@vger.kernel.org, miguel.ojeda.sandonis@gmail.com, rust-for-linux@vger.kernel.org Subject: Re: C aggregate passing (Rust kernel policy) Message-ID: <30fb630e-2bba-43d3-8d80-4ad553d503ca@paulmck-laptop> Reply-To: paulmck@kernel.org References: <20250226162655.65ba4b51@gandalf.local.home> <20250226165619.64998576@gandalf.local.home> <20250226171321.714f3b75@gandalf.local.home> <20250226173534.44b42190@gandalf.local.home> <20250227204722.653ce86b@pumpkin> <20250227163319.5b19a68a@gandalf.local.home> Precedence: bulk X-Mailing-List: ksummit@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250227163319.5b19a68a@gandalf.local.home> On Thu, Feb 27, 2025 at 04:33:19PM -0500, Steven Rostedt wrote: > On Thu, 27 Feb 2025 20:47:22 +0000 > David Laight wrote: > > > Except that (IIRC) it is actually valid for the compiler to write something > > entirely unrelated to a memory location before writing the expected value. > > (eg use it instead of stack for a register spill+reload.) > > Not gcc doesn't do that - but the standard lets it do it. > > I call that a bug in the specification ;-) Please feel free to write a working paper to get it changed. ;-) Thanx, Paul