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Wysocki" , Len Brown , Pavel Machek , Li Ming , Jeff Johnson , Ying Huang , Yao Xingtao , Peter Zijlstra , Greg KH , Nathan Fontenot , Terry Bowman , Robert Richter , Benjamin Cheatham , PradeepVineshReddy Kodamati , Zhijian Li References: <20250822034202.26896-1-Smita.KoralahalliChannabasappa@amd.com> Content-Language: en-US From: "Koralahalli Channabasappa, Smita" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SJ0PR03CA0052.namprd03.prod.outlook.com (2603:10b6:a03:33e::27) To MW4PR12MB7142.namprd12.prod.outlook.com (2603:10b6:303:220::6) Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MW4PR12MB7142:EE_|DS0PR12MB7947:EE_ X-MS-Office365-Filtering-Correlation-Id: dbb2ea3e-bb38-437a-24ab-08dde68b7bbd X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|7416014|366016; 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See one question > about the !CXL_REGION case below. > > Test case of a hot replace a dax region worked as expected. It appeared > with no soft reserved and after tear down, the same region could be > rebuilt in place. > > Test case with CONFIG_CXL_REGION=N looks good too, as in DAX consumed > the entire resource. Do we intend the Soft Reserved resource to remain > like this: > c080000000-17dbfffffff : CXL Window 0 > c080000000-c47fffffff : Soft Reserved > c080000000-c47fffffff : dax2.0 > c080000000-c47fffffff : System RAM (kmem) Yes, that is how it currently looks. Maybe we should also add a log message to make it clear that this dax is coming from dax_hmem and not dax_cxl? Another thought I had is that if we hand off fully to CXL even with regions disabled, we could avoid showing the Soft Reserved layer entirely (along with the kmem and devdax under it). The question is whether that approach would be preferable, since in that case the memory would end up left unclaimed/unavailable to Linux. Would be good to get your perspective on this. https://lore.kernel.org/all/a2e900b0-1b89-4e88-a6d4-8c0e6de50f52@amd.com/ Thanks Smita > > These other issues noted previously did not re-appear: > - kmem dax3.0: probe with driver kmem failed with error -16 > - resource: Unaddressable device [ ] conflicts with [] > > -- Alison > > snip >