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Fri, 9 Feb 2024 05:25:04 +0000 Date: Thu, 8 Feb 2024 21:25:01 -0800 From: Dan Williams To: Alison Schofield , Dan Williams CC: Davidlohr Bueso , Jonathan Cameron , Dave Jiang , "Vishal Verma" , Ira Weiny , , Wonjae Lee Subject: Re: [RFC PATCH] cxl/region: Allow out of order assembly of autodiscovered regions Message-ID: <65c5b72d902a0_5a7f2945c@dwillia2-xfh.jf.intel.com.notmuch> References: <20240113050421.1622533-1-alison.schofield@intel.com> <65a980249f50f_3b8e294a3@dwillia2-xfh.jf.intel.com.notmuch> <65c55c67ec60f_afa4294cc@dwillia2-xfh.jf.intel.com.notmuch> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: MW2PR16CA0017.namprd16.prod.outlook.com (2603:10b6:907::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_|DS7PR11MB7887:EE_ X-MS-Office365-Filtering-Correlation-Id: 42c31705-f2c3-407a-f1a4-08dc292f788d X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?brsWqF/y8pBz4jFLl3/uutll6IEN5lRif7Up/nuU5rogVaXAq0LfPHFQ0TS4?= =?us-ascii?Q?hqLYvcNY2fLLvg10KMfwdlBUsKeOtLyO04l2ve/DTP+lFY6sM5+NI6d1UkIc?= =?us-ascii?Q?cbYMc7JRuDn61R2kVyQIfgYZf4HxDPRFUnsWnq6WujWlU9tCdB66KXjv+ENi?= =?us-ascii?Q?2ML77FnJiqeDTlVEuCMRPmm6MFoerRnzW1weX273V46H7EUI6nDY+880+pnu?= =?us-ascii?Q?6HDFj/FrMStqCt5OvdgZhYc/9yjYP48aRLXofXuPmsQQn5i3uZXGhRunyviV?= =?us-ascii?Q?u/mwkIJFzCJkqARKSkgHFUQ3oy9jcMfwwFoTJjyM9BMrfpiF/gDb9iyYeJCd?= =?us-ascii?Q?xHeC8aA81qRzme5Ygqz6RBgVl/86+9eXkpBIgRQ/RhBGcYa8ou79fCHWpFWM?= =?us-ascii?Q?VX/OvXBvGISKIjLIsGhdaIPywgiVwWJLmR68Cbpxfzv0NQWOz8HdJB0st2ii?= =?us-ascii?Q?hwfA4PdY/o8I/U0oIrQKHIv6EF/qb9kMzOEA2PhH5iv9ffxQhKkCjCLJoxJf?= =?us-ascii?Q?qAILFO3/xspb1cpCADXhgj6bcc7hMqsN8UZaeIJVhssAFwPdUnw+j6GInTtP?= =?us-ascii?Q?sTUsm5LiNokOB+J5R7z6h7nypp0kmqMOa27Sme3CsTTWONNrJBSZjvPQJC/l?= =?us-ascii?Q?q87/8y53NzLFzg7pqUApYqmEiDKp+zAau7XqByQkC+ia/GiuLX3W3kjYAqCF?= =?us-ascii?Q?M0xIcjHUwAam3HREzhjG5Qudx8iG+woHnL74LLf209z29PdRWbiyWooOEClQ?= =?us-ascii?Q?eqafrhWuxQYBzB1J2S+fopdKJYDG4VUBM/okCYlS/Wn12BR1T8B6CqnbfQe6?= =?us-ascii?Q?uXqba/cY/OKNTHgLwbZ13C8FIJDlU/lT95KrPnYH+1qQ+dQF0h+jDLivA9od?= =?us-ascii?Q?ZPEfnJsyoXKaWIg2IH8g/bO6NSupFPIRbzEXN8n1NGisn2MLDn7ZORd2AExS?= =?us-ascii?Q?BjYYSp5V+ixuWLIFRRsqQnzvY0XUEwwthb9uzOyuLgpxYWNlPM11YCGUjDVf?= =?us-ascii?Q?3A+RQe26/TnB93Wjx/dG0WY+tVIoH3FvJCEiAs9t2Xh2hiRBmZUAdI7K1MCQ?= =?us-ascii?Q?Tm6/STuKHJJ75CcM13E0/5auyofZnLIUPYPhcNUlfhW0Zmg1hFytocB59ZQT?= =?us-ascii?Q?cC+IJwJP2cyPjURY/UFDx4jAHZnQJ1TWA5LN8tdhA1MthLl3U7B07OqLkj3m?= =?us-ascii?Q?Ab/eoSxhQ4EGkDoRK8K1SMg1pF0hN704Z8vWuLZ5va6q2/UPaMakEo7stX0R?= =?us-ascii?Q?r14lQQNdc/ustKdWPellO44mAE/fg2Bq1Aoaur13PfIWoAOJqWMqbuok3WBo?= =?us-ascii?Q?Jj+CfKsLQqqTZcZ2iIgZPAh6DERsp35rDy4t2y4M+ymqq9sHQojLCm/tUW+V?= =?us-ascii?Q?2HJ38dHnUVd7Q73oH1K6M70NIDnUKGhM7DcAMvhr/+ulephN49BnBjTCWen+?= =?us-ascii?Q?cSWjFNnHeQAG7H8vB0zLxVbP8RvjQkt2l4SwD3XhVU/I8nIO1NEwNq1/dvil?= =?us-ascii?Q?KpETrQl7rymm5/q4tvFawPc38PMuhppeVjTIMiqRoPC84jSS688mXh6HrWmM?= =?us-ascii?Q?YvhdDAB18sXHKt58ndJ0RNhImsqhNtTnV0TnVR/7cX/ID372SoHhkBSz7hVe?= =?us-ascii?Q?gw=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 42c31705-f2c3-407a-f1a4-08dc292f788d X-MS-Exchange-CrossTenant-AuthSource: PH8PR11MB8107.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Feb 2024 05:25:04.4112 (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: PX4PEf52pUu1vcojRM8RpcrCAlkCjoHGBJ/D12qxk/OKUtblhq478A7Xh9Ukdmlfj1RR7wI0X6DDPnW/Ki5Ux08PbmpFjbLDKTgp59C4ABg= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR11MB7887 X-OriginatorOrg: intel.com Alison Schofield wrote: > > I can see it being an alternate way, but not sure how to weigh one > > approach vs the other. Is the dynamic update getting in the way of a > > test case you are thinking about? Otherwise it seemed easy to reason > > that the registry is always on, but only takes effect when > > registry_reset_disable is set, and cxl_acpi rebinds the test device. > > The constant work of updating the registry caught my attention, but > no impact that I know of. The dynamic approach is more intrusive and > impacts the normal path needlessly. A snapshot approach limits much > of the impact to users of the new feature. > It does mean more infrastructure to walk the entire topology and save off all of the decoders. However, this is straightforward because decoders are devices on the CXL bus. I am not worried about the intrusiveness as much as how easy it is to conceptualize new tests. I do think it is easier to conceptualize that the flow is "get the decoders the way you want them, snapshot them, ..., rebind", ...rather than the current: "get the decoders the way you want them, disable-reset, rebind" Notice the "..." in the first flow where it is a bit more forgiving if you do some decoder operations between the snapshot step and the rebind step. Where the latter flow requires that you know the side effects of how rebind tries to reset the decoder state. It still ends up with the all same complexity on the read side, but should be easier to craft new static configurations without needing to worry about the write side of the registry.