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Mon, 27 Apr 2026 15:08:00 +0000 Date: Mon, 27 Apr 2026 10:12:02 -0500 From: Ira Weiny To: Jonathan Cameron , Ira Weiny CC: John Groves , Davidlohr Bueso , Jonathan Cameron , Dave Jiang , Alison Schofield , "Vishal Verma" , Dan Williams , John Groves , Fan Ni , Anisa Su , Shiju Jose , Robert Richter , "linux-cxl@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "dev.srinivasulu@gmail.com" , "arramesh@micron.com" , "ajayjoshi@micron.com" Subject: Re: [RFC PATCH 1/4] cxl/extent: Promote cxlr_dax->region_extent to an xarray Message-ID: <69ef7cc2a9b63_101875100a0@iweiny-mobl.notmuch> References: <0100019dbcc13648-596853f3-0083-46e0-b654-396eedd657cb-000000@email.amazonses.com> <20260423235158.3732476-1-john@jagalactic.com> <0100019dbcc1f7da-e3c5b4b3-6505-4dc6-9952-70a4676cbdb6-000000@email.amazonses.com> <69ebe836a8ea_bde13100d@iweiny-mobl.notmuch> <20260427133833.61b9cbca@jic23-huawei> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260427133833.61b9cbca@jic23-huawei> X-ClientProxiedBy: MW4P221CA0009.NAMP221.PROD.OUTLOOK.COM (2603:10b6:303:8b::14) To PH3PPF9E162731D.namprd11.prod.outlook.com (2603:10b6:518:1::d3c) 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: PH3PPF9E162731D:EE_|SA1PR11MB5897:EE_ X-MS-Office365-Filtering-Correlation-Id: d8717ca5-6007-4207-98c2-08dea46ec5c1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|366016|22082099003|56012099003|18002099003; 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What yall will want > > to do is ensure that the region extents which get surfaced are ordered > > based on the sequence number _when_ _the_ _dax_ _device_ is created. The > > order they come into the host does not really matter. Although yea the > > spec has a bunch of rules... so whatever, follow those. But it is the > > dax device which groups the extents into a contiguous HPA range and maps > > On this bit, HPA? Why would extents be contiguous in HPA? Contiguous > in the DAX device mapping sure, but not HPA. I'm not saying the _extents_ are contiguous in HPA. I said they get _mapped_ into a contiguous HPA _by_ the DAX device. IOW the DAX device has some policy(tm) which looks at the extents and decides which ones are part of the device (the grouping I mention above). Then it presents a contiguous HPA to the user by mapping those discontinuous extents. Ira