From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from LO2P265CU024.outbound.protection.outlook.com (mail-uksouthazon11021143.outbound.protection.outlook.com [52.101.95.143]) (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 6D19025F99F; Sun, 20 Sep 2026 13:50:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.95.143 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789912234; cv=fail; b=Ut9DY9N6E99oUrhnwOzjGqYMiZ9kh4j3S7MF7E9sH5M1xLnxFdouOkhEj6Aw9I0+g2uusjy9AB7znkV5OvBmd8Fp1rTB8tr06SLs0ZumBZHPJ6//E+qTbebaVOr7lBjjpbJxte0uGoiy7NPcIIr39P/+R//RrSRuSz961BPMBfk= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789912234; c=relaxed/simple; bh=viqJ4MxOJ9y9JGwM6+qrbujBSNGRtp4C9GhxBdEMOw4=; h=Content-Type:Date:Message-Id:Cc:Subject:From:To:References: In-Reply-To:MIME-Version; b=vFKrPKWvSGEbZrBn19hoNxG6QzuVMK6hM0mp2Bc9t/SdZHjREXIfNIIPpGYiLWcjz0g9+aWIhFU5HQf0wl12JUq+IfJA8U9+EOqC7i8YOGn1kYbyUBbVF34I8iF/9w3b4/2xDZY3tWFbwmUMZ36nHX62SVn5HRp+oB51NGidNFU= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=garyguo.net; spf=pass smtp.mailfrom=garyguo.net; dkim=pass (1024-bit key) header.d=garyguo.net header.i=@garyguo.net header.b=rI28Q8d4; arc=fail smtp.client-ip=52.101.95.143 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=garyguo.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=garyguo.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=garyguo.net header.i=@garyguo.net header.b="rI28Q8d4" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=ZIvXVl/sem216gK7wp/bxKR9HNZRN3zssVW0/7nWoj0BxiNktsH2LbcCV8CSC75Xyc0gqEE1FomCwq4kzrvvnxN92CcgCnFiWGeqjLzoiFEKOmVIyXNgFPap/WiZ5+2MHulsN5xz9oP+MVEITxeOURX9PjciE6E2Cec0mnBy2LjkeyYJB4NDe5iZf78Qt1ZlYAvoUGvRmRADINcfX43Xd1dEFK5VnbvRQLn3raOuvEOMekiCx6603GkfGwMnNz6OYhPQN5gZu+t4USNWdQel7e10CBpRftWjZP+1Sq0j647V70RmuakNJcFAJPphssyrGfk9w95OvgYl4VGugVbaVg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=viqJ4MxOJ9y9JGwM6+qrbujBSNGRtp4C9GhxBdEMOw4=; b=kidAIYaJdGnTb1aqZzeGRVWOijJddJvhMsgFScDPfsKyWgINvXOLI8NRbR6EQcjiOglRyTBv7hLBZ27UpmeYxsd7hy8Ih7d99o90kp64fuLpymMQISVGnFCS8wu9O3HCIuXufCNfUcXA/c0FeySyCxqeMJReFn4np+xvEzroH7tARyY7/fcQJWavyiDzjFKS5kcSxw4DyHjihTSFsKHK79INlKphpAL1ANB2HzB9NNgxemf1vZb8TdbRawFCzUqaD3cR6Egae6LC6xw41MkfFTvA8D39S+67FJLSovkq0dJlJoTgPLp8els5pWayWmIdI2bmS3I4bToSup1zXGL25w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=garyguo.net; dmarc=pass action=none header.from=garyguo.net; dkim=pass header.d=garyguo.net; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=garyguo.net; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=viqJ4MxOJ9y9JGwM6+qrbujBSNGRtp4C9GhxBdEMOw4=; b=rI28Q8d4knSnp7Qr0QGUaJIJscdsHsPfQvrQTLe9ellFLDbpFX0QCCxDAJdLQFruw5N4W4zWX8JNy7OAMbqbszqDSbyRGP1w5WEjwbHK7hxdGaEkwDoMG3VvqjMlPcd5ClxI1Zs8QXXEb9kQpXqyxi2wfjhESpMkmunjUm4Shu0= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=garyguo.net; Received: from LOZP265MB8551.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:4b4::24) by LO0P265MB6291.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:24e::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.428.16; Sun, 20 Sep 2026 13:50:28 +0000 Received: from LOZP265MB8551.GBRP265.PROD.OUTLOOK.COM ([fe80::c07d:488c:d4aa:2a4a]) by LOZP265MB8551.GBRP265.PROD.OUTLOOK.COM ([fe80::c07d:488c:d4aa:2a4a%4]) with mapi id 15.21.0428.011; Sun, 20 Sep 2026 13:50:28 +0000 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sun, 20 Sep 2026 14:50:27 +0100 Message-Id: Cc: "Alexandre Courbot" , "Eliot Courtney" , "Yury Norov" , "Miguel Ojeda" , "Boqun Feng" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Alice Ryhl" , "Trevor Gross" , "Daniel Almeida" , "Tamir Duberstein" , =?utf-8?q?Onur_=C3=96zkan?= , "David Airlie" , "Simona Vetter" , "John Hubbard" , "Alistair Popple" , "Timur Tabi" , , , , Subject: Re: [PATCH v3 1/3] rust: num: add cv! macro to create values from constant expressions From: "Gary Guo" To: "Danilo Krummrich" , "Gary Guo" X-Mailer: aerc 0.22.0 References: <20260902-cv-v3-0-0f90659e711d@nvidia.com> <20260902-cv-v3-1-0f90659e711d@nvidia.com> In-Reply-To: X-ClientProxiedBy: LO4P265CA0006.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:2ad::20) To LOZP265MB8551.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:4b4::24) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LOZP265MB8551:EE_|LO0P265MB6291:EE_ X-MS-Office365-Filtering-Correlation-Id: 925215e3-64a5-432c-3e02-08df171e2130 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|1800799024|366016|7416014|376014|10070799003|6133799003|10067099003|4143699003|56012099006|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:LOZP265MB8551.GBRP265.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(1800799024)(366016)(7416014)(376014)(10070799003)(6133799003)(10067099003)(4143699003)(56012099006)(22082099003)(18002099003);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?cVJwMWZEMUErVjBxUnJ4bjEzaUJRV0dqTy9DUVFzb2VvQ1ZIS2hsS0dTY1pz?= =?utf-8?B?N2tONG9BUXRHaEJlTm02NFozMkRqbmFiOUZObGtucGpIMG5tVm5sS1dMV0pm?= =?utf-8?B?MDNjTXlMMG9kb0M1M1JDeUpEZHlBQk9NOUJyUVd3Q2YwMUcreVNIYnFFL2lm?= =?utf-8?B?dkJ2bXFEUFlFMmtNejhyekxoNDNUNlViR3pxZFhCc0djL1hoYjNQWUl4WHNJ?= =?utf-8?B?TFNSR1NONVpXZUlWM2ZRZThUeE5hVDhiSkQ3YktyOFZDNnMvMllvSlo4OUNS?= =?utf-8?B?dmZSNTFIdUNHUFZNLzRVUEU0L3lMdlh4WGg5NThmM09ZVGdXUU9ORnYySjZ2?= =?utf-8?B?dWUxdGpidmVZOG5sNzBGb3BkWFpHNGxmMFdPQWlOSXBiUHNQK0IvQkNNelNJ?= =?utf-8?B?OUdGdGYvTWpteHJoS2ZJLzdoaEFwekJWWU5vay9Oa0NRT2R5WU9IR1hHZXli?= =?utf-8?B?M1YxRVYwenBDVm9Uams2c1J3K2JZbW1veDd4aWNhZ1pjUGFPclJSVVRnMDkr?= =?utf-8?B?T1Z4M2ZxeUVGOTNOTzhLTzBJdVN6bEdXODVkYUJWczdlRkI2R0gzS0lGVE1S?= =?utf-8?B?bU9SU1N3QzlRQ3ZHWFl5QnptME5uSEozeWMxbTBjLzRvZm9jRzVrWkR4NUN0?= =?utf-8?B?eGpWWmkwWHdYRnpkOVRETzA1MERZMi9Kd2h0Q3Vqa2RyUzIrVHltem0rNW1S?= =?utf-8?B?U01GckEzRnJFdElCT1FFdnJURUFYWmVXeklOUzNaMVJzcGFNQnZjNXNybEpq?= =?utf-8?B?MDFCQVBaTlEzWHlZZ2U1YTZYWGZxZC9RVW5pVURSYWpwYXdESFNaY3ZrcHRt?= =?utf-8?B?TkR1LzRpbFNvMzh1QVBEdC9sR3JMRVJzL1ViV0JjMkFkWmdJZ3h5RWNnMDZH?= =?utf-8?B?S2FUWWRHQjRhRnNpclZ2cU81dGE1UjBhdzBvaVN4QkZ6VUtNdEJUNnlLUi93?= =?utf-8?B?cWNBREtjU2JaWmt6VUZIQy9ZU09tclJsMkUxTElxNktHWndNQjNobzN1SVRT?= =?utf-8?B?U2pjZUdkL3Y5cTNJVDR0NVRVWThVU25RY1ptMDhSc0d2eHQ0WnpnLzRoQnpv?= =?utf-8?B?WXZoaldpQlM1R1N0cGNzekhxT29rejJKdS9nZEJWZHVsVlRlZmRscHJMbXU3?= =?utf-8?B?WVcwWUxyV2d0YWJOMCtkaldaVEZZb1FEQWt1ZndkcHNhK2lZOElLOFdCQURS?= =?utf-8?B?SWF5TlNrYUxtOU1tUUt6cm5FNVp4dCtmcUlNNDUwT0wyNUJKMFRhRnZqTWhY?= =?utf-8?B?dkNyWVBWV2FIdW0xVCtrMDRFblgvZkZab3NiOU05RE9lR2lnOFpzYkhSQmha?= =?utf-8?B?M2NoR2lqQ1loK3Z0MnNDc21lK05oZ1k0am0xWlpHSzVlSUoxL0FpU1ByUU00?= =?utf-8?B?MnF5RGlrOTFOSlhobVA2QVhUck9yZWcvZVV1VVlLYzNTZUNPMGRtMGZPZ29n?= =?utf-8?B?ZkhsT0dPUitMSWhNSzBpbDBtUXdYYmM0MDdraU9CKzU0RG14L29SUGd5UFNv?= =?utf-8?B?WXJWbkpzcEw1ZE91QnhYNHZ6OXA4QVYvUFNaRTBuL2kySGJkQ25ucU1NWWRQ?= =?utf-8?B?cVJlUE1ERFY3NHFOUDhTalRSVDBSZzRsQ281aXM1UzRlUVNUMlQyd2J5dm0v?= =?utf-8?B?VlJocjdWdGtFV1VpZVhwSjc4a3JGOUtYZnRudW8xUUd6dE51Smx4U1k2VXVU?= =?utf-8?B?MEVtM0VVVlVxRk1rMzJMdzhyK3NxZ21mMmJzREh0N0JBQ0NWWHlJUFpEWlJm?= =?utf-8?B?TjhodENhT1ljNFB6Y2Vad0NzN29WZkFiYXNocWcxSXQxZ2oyUFRGTWFDWXVS?= =?utf-8?B?K0ppd2RUME1RUzRHY1pWdGZFWEhXUUxwNjE5MTdYM2cxUk9NU0NMY212Tkpm?= =?utf-8?B?SEtYdGFlRnhmcXFhWXpQWldMdzFrNUJCRGxsTGdJbUZyc2F2ZDdpZWtCNnFi?= =?utf-8?B?U2pkRUxvVnNGNTRaWXBIYjYxV1FsSm9lUXlOcEtjdUtHSlByUDA3TjBLRFdS?= =?utf-8?B?bWQzWWxLallOWXY5WjJ3d2dGdkk5UHl6VDU0ZkJJNFAzeEhvbUNIWlQwbmFI?= =?utf-8?B?NVljTXBWay8rcDBYQi9rNEkxbXZodzRFM3Jka0NZdzVRWndnU21tdDBySTZI?= =?utf-8?B?NW5OL1NqWjE5ZjNxcEFjaFFhN1dKcDlRdTcrNGN1WWdaNU5qVkkvNld3VHVw?= =?utf-8?B?SDh1WllVc2ZNS2Z2Z05mQ283OTRPdDEyNFlDUVpxa0FITlBuQ1ZXYjRPRUNy?= =?utf-8?B?akRWMkU0RW84QWdYTGFvaUtoRjN2clFPVXkyWWJjUVBHK1BXeXh0VHhRY2xo?= =?utf-8?B?bSt0RjVTbGtaR2p2VnhHdUNCdEd4SFBPS3JvQ1REaVEvT2ExRGxTZz09?= X-OriginatorOrg: garyguo.net X-MS-Exchange-CrossTenant-Network-Message-Id: 925215e3-64a5-432c-3e02-08df171e2130 X-MS-Exchange-CrossTenant-AuthSource: LOZP265MB8551.GBRP265.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Sep 2026 13:50:28.4155 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: bbc898ad-b10f-4e10-8552-d9377b823d45 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: f4SA8ay99k3rQkg6s5H9XRnY1yvl/5Q7MP0dG8s55ov1y1DryZ0qYwWVQjkAYmB+S3+g2jLpNoY6ZHGm+aO9nQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LO0P265MB6291 On Sun Sep 20, 2026 at 1:38 PM BST, Danilo Krummrich wrote: > On Sun Sep 20, 2026 at 2:20 PM CEST, Gary Guo wrote: >> On Fri Sep 18, 2026 at 7:03 PM BST, Alexandre Courbot wrote: >>> On Thu Sep 17, 2026 at 9:53 AM BST, Gary Guo wrote: >>>> On Tue Sep 15, 2026 at 8:39 AM BST, Alexandre Courbot wrote: >>>>> On Wed Sep 2, 2026 at 6:16 PM JST, Eliot Courtney wrote: >>>>>> Currently, using NonZero/Bounded constants is quite verbose. It's >>>>>> unfortunate because it disincentivizes using it in interface boundar= ies. >>>>>> Introduce a macro to make it nicer to use. The macro `cv!` (for cons= tant >>>>>> value) takes a const integer expression and widens it to i128 (at bu= ild >>>>>> time only) before passing it as a const generic value to a new trait >>>>>> `FromConst`. The value is then converted and appears in the >>>>>> associated constant `FromConst::VALUE`. The trait is implemented by >>>>>> NonZero, Bounded, and Alignment and lets values of each be construct= ed >>>>>> from constants without a verbose turbofish syntax. >>>>>> For example, `const { NonZero::new(1).unwrap() }` can be written as >>>>>> `cv!(1)`. >>>>>> >>>>>> Suggested-by: Gary Guo >>>>>> Signed-off-by: Eliot Courtney >>>>> >>>>> I don't think we have any user but nova-core at the moment, and it >>>>> benefits from this in several series (patch 3 here, but also ID pool = and >>>>> later r000). Miguel, is this ok if we take it (i.e. the next revision= ) >>>>> through drm-rust-next? >>>> >>>> How about a topic tag shared between Rust and drm-rust-next? We could = also >>>> remove the old num casts API as part of topic tag and fix all existing= users as >>>> part of merge. >>> >>> Not opposed to the idea but IIRC there was already some pushback to the >>> idea. There doesn't seem to be an urgency to remove the old num casts >>> API that justifies doing it now with a more complicated merge path.=20 >> >> Sorry, what pushbacks? I thought that `cv!` is what everyone agrees on. = I see no >> downside of this compared to the turbofish const conversion APIs. >> >> I am not opposed to delaying removal for the next cycle, but IMO the `cv= !` macro >> should be present on Rust tree so it's visible and improvements can be m= ade from >> there, so I think we should do a topic tag regardless whether the old AP= I >> removal happens or not. > > I think Alex refers to this thread [1]; there's was some more context to = this > though. Right, so "pushback" here relates to the logistics of old API removal, not = the idea of `cv!`? Best, Gary > > [1] https://lore.kernel.org/all/DL0KDAXUZOXD.I8FBZZ51EIIF@kernel.org/