From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) (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 CD06E21CC62 for ; Sat, 13 Dec 2025 03:36:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=198.175.65.14 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765596993; cv=fail; b=Qqvn6tVe8034IPzl6NufVUUr3Gm6tXx/pKoXOfBMssCPP/xKrOQ139ND2DpRN0JLqxPx+tU9gkqkB5scXO552475aQvyJDXIMh7HLDsdm4joxLqHWaH6XnV6HLYY95r1RzwlsST0xSe62sFZSNb+7qXxUixhh0fxaWfOWCudn04= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765596993; c=relaxed/simple; bh=s2/7nzQ5iJ7ER/XvskkkxPP2nYL8YQv0x2xX9jHQDi0=; h=From:Date:To:CC:Message-ID:In-Reply-To:References:Subject: Content-Type:MIME-Version; b=Rr5U1TYVS6GcmaiS7Bb+S70glVvd9cAYFyybqMnIfPwPQij8lycK8TyG6OPeYJUqfGEkuP3h4AX++JkwmTWCMNxBP97zIg7DN21cGoJh0Vs17It3uFaT3OxRXnZYM6BOpY2wlm6r46Lo++Vx73lzYWsWL9VUnpMsATr1wSfI4BQ= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=IleVQycH; arc=fail smtp.client-ip=198.175.65.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="IleVQycH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1765596992; x=1797132992; h=from:date:to:cc:message-id:in-reply-to:references: subject:content-transfer-encoding:mime-version; bh=s2/7nzQ5iJ7ER/XvskkkxPP2nYL8YQv0x2xX9jHQDi0=; b=IleVQycHVjNOQ7wiEL8l1tklU42qE2K2T/uFcd6rFObnZygQCqQ3Eejm UDpa/G94YL4qH8FGtJrtpTMaTZEKnq+y4I4zOgi0uMQjiZCsLUjrWcMQq ZOJ+g8Q3jL7Lsrs+ggnZc+tDmmwVXQEJmtrzuj/FGRhpV2apCYpI4bNsI 1d/xkgOrnHn5EMCT8idYW835yjo3srxzWWuxFrtSvakkEs+Rhn5Wq2WFG bix+NjmUAkja06hL6wcoR4z/9zmqcE4wixyd77LIK9a1M2jtIbI1w5nN0 vfeLUD2bxOfPWkTwkuw3eIk/BlqkiELDOH+28nF3XzvG5Sth+N6PRV/6J g==; X-CSE-ConnectionGUID: +aOJPoajTVK1fzgnxvW46g== X-CSE-MsgGUID: mY/qruJ+QlmTOhB9fXvcsQ== X-IronPort-AV: E=McAfee;i="6800,10657,11640"; a="71456161" X-IronPort-AV: E=Sophos;i="6.21,145,1763452800"; d="scan'208";a="71456161" Received: from fmviesa010.fm.intel.com ([10.60.135.150]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Dec 2025 19:36:32 -0800 X-CSE-ConnectionGUID: faoDUTJWSi234guAjkQChQ== X-CSE-MsgGUID: FuuT6t8dQmGb+LqEKsef8A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,145,1763452800"; d="scan'208";a="198068441" Received: from fmsmsx901.amr.corp.intel.com ([10.18.126.90]) by fmviesa010.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Dec 2025 19:36:31 -0800 Received: from FMSMSX903.amr.corp.intel.com (10.18.126.92) by fmsmsx901.amr.corp.intel.com (10.18.126.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.29; Fri, 12 Dec 2025 19:36:30 -0800 Received: from fmsedg901.ED.cps.intel.com (10.1.192.143) by FMSMSX903.amr.corp.intel.com (10.18.126.92) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.29 via Frontend Transport; Fri, 12 Dec 2025 19:36:30 -0800 Received: from BN1PR04CU002.outbound.protection.outlook.com (52.101.56.14) by edgegateway.intel.com (192.55.55.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.29; Fri, 12 Dec 2025 19:36:30 -0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=kfHgz7MKzPg42VQS0NhcPyVSL7fPlg+8AVWTbhL7cHhb9jVsUIV61WbbZq0h5Pa5nWgLq9ObW32eBShb5y1Ci+eMWQc9Rv/JI4rxkEC9W5/k8iYkgpedMMEFbEb+ONKr2x6Nf99cK0dBVA0GPdaNrRe3mwkNKYYYiYKUlZzwXCHZRHVERmKiVVrIlRQ7iR8oG2zmoBb7HwQdw3qbRDrZv2/bGqDHWdOcgjBnJIAjSya4wk5vfia8JWVCvOh1+TGgxcqjItux2RPrvYcw9EwnlaqK7ST5v9BD7L21RFqa+WlDGwJycZcxw+KkV6rIVszwOpQESl+M9WaEfXaPKC2qPg== 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=qlTanUOrUkYdfoYHFIM67HX847D0uHuNP6c8QJnFSnY=; b=WsdGaTiiPomvl374MnPYm8iLtKWlNnFerpMbdhBMakIOVLd7PIEUleNZ18xjwmpychT1IaWwBm+qbsYQiYAIuIRIwSKhBqGHdfXLY9Rxzb/bI3acsFHAQ3fsb02/G/d/+Xbwb6sAyOYi07rL9t7yNlNhP52lB1xK0Xrz0azsNVU/hEPXFwNY0a9++GggzxCY+0W/6uPy3Vou0LuSUxpHgvpys1p7bzVK1WYm6kiCvXOhnDGgiBmKbiQsjDt4N/dRRHsoiitQNsr8t+/Wr04i+iTpCha6N3fwFUcvc2taVd4OkoeyG1pTZjz9JOd2lGhSUe+juybHZp/KuDFqjCq6Uw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; Received: from PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) by DS4PPFDB7809488.namprd11.prod.outlook.com (2603:10b6:f:fc02::56) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9388.14; Sat, 13 Dec 2025 03:36:28 +0000 Received: from PH8PR11MB8107.namprd11.prod.outlook.com ([fe80::1ff:1e09:994b:21ff]) by PH8PR11MB8107.namprd11.prod.outlook.com ([fe80::1ff:1e09:994b:21ff%4]) with mapi id 15.20.9412.011; Sat, 13 Dec 2025 03:36:28 +0000 From: Date: Sat, 13 Dec 2025 12:36:24 +0900 To: Anisa Su , Ira Weiny CC: , , , , , Message-ID: <693cdf385657a_2e71710083@dwillia2-mobl4.notmuch> In-Reply-To: References: <20251203203540.1091827-1-anisa.su887@gmail.com> <6931c4c85a526_43de3100bb@iweiny-mobl.notmuch> Subject: Re: [RFC PATCH 0/3] Add Support for Multiple DC Regions Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BY3PR05CA0055.namprd05.prod.outlook.com (2603:10b6:a03:39b::30) To PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR11MB8107:EE_|DS4PPFDB7809488:EE_ X-MS-Office365-Filtering-Correlation-Id: 7849fc3d-bc06-46e6-418e-08de39f8cc6b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?NU5JNC9iR3VYNnpvcHhFTEordkg2Qys3K0xHR0VQczlhaGJGVWp6dnd0NnZV?= =?utf-8?B?ODlERVdLczQ0bDBiWVc4eW95MUJrMzBsbm4yYW9QbEFjR0lUR1pNcDNsbEdo?= =?utf-8?B?ZVdiZnRSTlBKS1VwWGgyc25VVkhMUy9NZnczeFNka0hMREUxVUxGclE1bHJ0?= =?utf-8?B?eHdUU0tyZ2lvN3U2dy9acjZLM0tmN011MWRibWpJNGR0bER0QmxWUDBxTm1q?= =?utf-8?B?WUJSLzBTZjVQLzVvdmxLZVlZT29uU1BFM0hqbmF0clBuamdQVHd6REo1amtQ?= =?utf-8?B?cHZzZnZzbkQyRWlGYW9rSUtMVHUzSXdTdS9sNHM2S1F1bUJoaVVPanlOaW13?= =?utf-8?B?aUxuZ2dkWkxvTTB5UGJ1Q284cVZwZWRMQkZMektqc3pyZGgrdDNHaTFwQ0NT?= =?utf-8?B?MEp4ck1mYnBXUXRtdTRyd0s4UGxNYXFmUXRYcWg2cnlYcml3eFlpZGo2MXV6?= =?utf-8?B?dlZvcisrTFRyYXhmU0lRdVBZS0hKaFZ5K1ZpNUxuRHp5UlFxRVZLR2I5K0pl?= =?utf-8?B?WlUzNjJoUGpaKzJDVnU2djJwb1ZiRUNpWk9pQVZCTlhBQ2RtajJPM3ZNcmtr?= =?utf-8?B?bHphWWx2TVh5OC9VazBvUkFZWFBrdGZSMUVxM21kbTdmWkJEam9VbzJrYVZG?= =?utf-8?B?OFZqSGNFV1FySlN1RU5iamhERFVCYU1DSUdyQmFsWkNiODFybVZnQ3dFTk1K?= =?utf-8?B?YmM1NzlJZnc4ZnJ2cURJRGtnemJ6eVhmTWE5YXFScFRybnZWUGw1VWdteFNk?= =?utf-8?B?UldOM0NLZjJQMHA1dTNHMmt1dE5rS2F2TExnK3RUYTZpaTNObExKbCsvbDhs?= =?utf-8?B?ejZvR1Bha2tSajlNVms1UGtaenk2QjhMbnJib2daVmFXaHV0SFZlRG1HNi9K?= =?utf-8?B?TjlodGpPdnVqUkFoSjgrdjJpODI0ZGM1d0JlK21SSFUrWDB3dE9LNDNIL0Jj?= =?utf-8?B?bHNmN082UDZreGEyN25MVGlRZ2J1SkE0ZGZGN2RUV1lYWXR4TGdhdEo0VVJT?= =?utf-8?B?bjZUNFNHWGlpZE1FbkNHNENZKzA0MUNTczBBQWJsK1NOSytyQ0ZMaWtHRXEw?= =?utf-8?B?MXVheUVhSVZvcnl2eHE3MEtaMVN0SWgzZVVZbXZ0TkFFTm5ZVUJYV1hGamRq?= =?utf-8?B?VDh0TXhobllQTi96QTZqUXMwc2VYUGxLZjdGdzJ1SGtwZXJENDdxUUttRVlT?= =?utf-8?B?QWljdEQvY1dYRis1ZXJvOHhhUDJUaTNFaURBdWp6VDBXc0ZaYTkxNkt1TkVr?= =?utf-8?B?Rm5jZWpDYWdmNG82eXM5RFZrWHlMUUE0a09LeDZoMHUyNklxR3U2N0VVc0xY?= =?utf-8?B?UW13dDYzUVE2YWxpcVNlVk5kZjNlZnhieEJCVmd5UzVFSFpHa2xMdUZrNzB5?= =?utf-8?B?dGVDeGdtMHVDdHdmNEllZFRsbEdudy80Rm1YWXFPTG5WK1lZOXdHK2Q0aWd1?= =?utf-8?B?TEpFK0VmYXBGamVjVlk1cThxN1l3NnFQSVNxMjgwRjZnT3RmcU80cUlEa0k2?= =?utf-8?B?MUVUUm9lWHJkbEVweTl4UkZPOWZ2NndHVlk5cHN0eStaZUtmM3c5L2NzRzhT?= =?utf-8?B?SG9sME50akN5MWYrMVJzTUdXY2Y4dS9uVW84UENXR2puMGd3TW9CS2JIbjkx?= =?utf-8?B?b2QrWkh3UWhxQlllNmdiWGZQVklEaE4vaWJGTDZiZk5Sam5BQ0pRbElaWWl0?= =?utf-8?B?N1Z2SGpraUh6R2MwdE5CR28vRHBKaXBGRUk5dnJDa3N6RlhrVXBnMHhoWTVQ?= =?utf-8?B?UGhoRXFLYzRBZ0xaR3RYRDVCcXZQYUdhNktPNENna25BU2x2cjVic1lseEJP?= =?utf-8?B?dWVSSDB5Z3Q4Q1FiWUxyYzIvT2U2VHFTWVBlTHc5ZVhwZER5VVo2UFFJWHBp?= =?utf-8?B?dTI2TXRrZlBSOG1sVlNFM0cyY05Pb3dabmtXSDlzWkxacjVkVmR5bkFsVnNW?= =?utf-8?Q?NFDwmUJp+esmSbO620Emt7mjq0E+L9S+?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH8PR11MB8107.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?eEV6L0pEWDA2bkVqMU0reG5oUUEvTGdPTjBJWEFKYzc4T3lic1VRMW9pY3ZP?= =?utf-8?B?RFBtL2tnR3J4bEhCSWJVYy9PUTBkMHFBVjhkTFArVkJiVXExcTdyT3pLM2V3?= =?utf-8?B?dUd3eVE1UnlsdmFpUE5LVlJPV2h2OWhBK3dXQTFWTDhkOHZ1eEdsY0s0KzY5?= =?utf-8?B?MkVoMUducmJ1OGRWQWlGT0kxWWxacnlGRkZLemFsaEZHdWxaRCt6NlJOYUlO?= =?utf-8?B?djRGY3hXdm9pLzA0OFJNcXRQdzh1aDZob0c3U0Frb3QvRE9vQXJVYjFBY0hi?= =?utf-8?B?VS9SUEh6MVB3S2NsV1VabENYNC9YVEphN0NVU2szeUlvUnFTNzNNZzJNV0pT?= =?utf-8?B?RnM1aTN1NGxPWmdDVERocWh5NWpFeVRQb2Z5cm5PL2x5b1pGekM5V2trTnFh?= =?utf-8?B?YVlEczNSdnphblJjMTZaTDNkMWNVMkhEaGk5cDNEWHdoZ2RDN1JtcHhBbXQ4?= =?utf-8?B?aXA3VzVlVFd4VVA4YnZwK2o1MEMwWWh3SWJRRlJiSTEzOEdPbEFQd25zclZX?= =?utf-8?B?QnJVQitDZTVvWm8yV2xCYlQvSjNuOVYrR3k5SHEzUWN0OXF0YlN0bXZXbHZw?= =?utf-8?B?VmVyN2I1NkhmQ2FxNnl2cStvOXJsUC8vNzl6bTZNYnRqSmZCSDZBcUgzS0JI?= =?utf-8?B?ZGZFSnhTUXpOSUw1UEZncXhRZmJYc3dxS01qSHlQQ0gwcEpqTEdFU3N2eThF?= =?utf-8?B?SnBDU2dkUDI5ekpGVGxjT3RHTW9KVkVoTzR4OUpSQVBNZ3NzRlQvbDkwNG5Z?= =?utf-8?B?Vi9XVGcvWmJxbUJTN3hrUzBDczM0UlFrNS9jTWVBdlV6QkFick1Wb0phbHNv?= =?utf-8?B?eDN4ak9xTHNTYkd4cTMvdFdQNDVIZFFJUy9XcmZka05wbXViZncyRUJWaitS?= =?utf-8?B?VWhOb0kvVE9peDFDa1k0SE1rSCtWSEhUcThaYy9LSytYeGFwYnoralJQeFZY?= =?utf-8?B?a0ZSS1VBeHhCMVdQWDhYOWE3WDVPY1o0ajlUaTlkVFg5NjJwY2Y3aUpxcDVx?= =?utf-8?B?ZHBUZEg2OGcrTUt6bVlmSXdmZTV1cmtMdG55REphVkV1aE1ZQlphWThNaUFT?= =?utf-8?B?Tnhmb1lhWG1iRjcxRHFiUlQ5SGhNdFB0d2lGSDN1aTdadkxGVkxEZkhyTEsw?= =?utf-8?B?VXphbjN0NytEcHEwdVJDWC9IcmZlNlhHckhFQ084Wjdqcm5xTlVZV05aZWFL?= =?utf-8?B?RjkxejJybGsrZkZyUndNUWJrM0RodE80VlNJb0dLNXYrNWdnSUtxREJ2L2J6?= =?utf-8?B?Sm1tSTB2YllROFhsM2RaNTdJVFNnNFVlWk5MOWZPeXhBMlh0MzZ1bm1ZV1d6?= =?utf-8?B?RHhkSVFEWldFMkFodEZyNWQ2cjdZdFQ5aEg4eUNYRkduWFlsS2FhazVTVU0y?= =?utf-8?B?ZitNc05MZkRYcVgyc1ZsOWg1Ymo4TXEyZEZxUWtyMklpeHA2Z05xZ2NXeG1R?= =?utf-8?B?UDhOZWxYQ1pQeVE3T0hqR25pb05Fb3luYXlneWJFWWVnZkVMa2ZBa1FYaDl0?= =?utf-8?B?cTNOdXBJS2JjLzk1aXlTcXVxS2hSeDBUMTdEQmtUenUvZnpPYTd6VFpQeXFG?= =?utf-8?B?UDNwSU51aURsaDlqTUlIa0U0bHJmUm9yUG9ydHdqNDZFNjR6MGx3L05UaXpK?= =?utf-8?B?d2I2b1NrZ2tNaFdyekNKbUtaR2d6Rndld2JlWmFxNUNab0ZPL2FENUl5UnBk?= =?utf-8?B?QmdKRC9jSkpZVUNBVFhUM3hMakYxcmZTcHZjcHhzWDNtbnZNQ2NvWjNENWxt?= =?utf-8?B?VnhQMDh4bmJqUTZ5STE0RmkyUGRuYjBsN2t5bDVibHZlUkJuSUtWT2hxUmVs?= =?utf-8?B?ajFSZVJkSkV1NDJIUW5rV0pUaG1PdDFoL1dPai9vREtqMDhPYll2UFdCV3lS?= =?utf-8?B?TWJ1U0xPZ0NqMnpBcFYyQXFCQWZZRWZqTDh1SDRoZzhSU3lJOUZlSFJQR1NH?= =?utf-8?B?N29BbHFjaXBtVDJ3OEpFbDVRZWU2RW5FcnIzZkZBcWRJNE5oUHBaZmtoN0dL?= =?utf-8?B?bXlwWnQ0RSt0OW9YdFRoSGdRaG53a2hQNnR1TElRZFdwYXhsZE9pQXZmT2Nv?= =?utf-8?B?Ny9FVUlGTDRSemlsNEcrSFpnM1JNa2pSM0NhWiszazZPa3RxdVV5TGRoTmpX?= =?utf-8?B?cnpUdjNERmFJdlFSamJsSGZGYkVseXJEbFNZMXhRd1o2UDZuNjFHTkdnaEVP?= =?utf-8?B?b1E9PQ==?= X-MS-Exchange-CrossTenant-Network-Message-Id: 7849fc3d-bc06-46e6-418e-08de39f8cc6b X-MS-Exchange-CrossTenant-AuthSource: PH8PR11MB8107.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Dec 2025 03:36:27.9866 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: x28Na9biGZZy9jBuarxfQ49NAMlnfDhEeneegHnD1nFv1vky+pn4QSsRC6J0cx4uSCXw/L4elBehVYWT8hENf9jMb0D15MTU4i5FaSoi5m8= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS4PPFDB7809488 X-OriginatorOrg: intel.com Anisa Su wrote: [..] > > Unfortunately none of the details presented in this cover letter really > > show why the kernel needs this additional complexity. > > > > Can you go into more details on the use cases of multiple partitions? > > > From what I understand, the motivation for DCD as a whole has always been a > blocker for the entire series. However, this year we've seen multiple vendors > demo memory pooling/sharing at SC,25[1], as well as the development of a > controller that supports "memory pooling and sharing across > multiple hosts" from Montage[2]. > > The flexibility and control provided by multiple partitions is > an important capability of DCD for enabling composable memory > infrastructures. IMO, adding multi-partition support back in from v8 or > picking up this patchset would strengthen the series. Can you explain the use case for multiple partitions per-device? Describe it in terms of what Linux loses if it never entertains this aspect of the specification. It significantly complicates the ABI for a benefit to Linux that I am unable to articulate.