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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?CiWDqfkPrdReS9DMQ9UOTFnmIvPWn1MavuCcfw1F3z1MQc5sk2vRA/d3o/x4?= =?us-ascii?Q?8dfeW11OQvm0WrI0D5SI3BNdCb4X/5/ph+c1VzXd7AJ25SsqiSeYITBL3S8i?= =?us-ascii?Q?pyaIyun62/uqLNyOpt79eUymyAU26eg5XW9MxloIFAg17TWg4LEJRNg3V0I0?= =?us-ascii?Q?Xc+nS3Hw0lX9rPlWIPuc5WtPm/VwTgXoogj2IuOaKbBGA4pR7Ymb6tRgUkTG?= =?us-ascii?Q?s6rDE5zzpG8xmnzVmbfTo+Ryk6pPGGokrmodX44e3IWzzBFoouIKhANWIRfb?= =?us-ascii?Q?Jyf7AtsGIMH3wCPMzJqlWSss4xWsRnez5qo+dbZRuGEM624gWAFZoDgt3vMm?= =?us-ascii?Q?KRkABn6o6qzhzwBVpUdYvQKduz5dR6/+COjKZLiDuerZCoWnNMcsRms4pCl5?= =?us-ascii?Q?BG/Gji6o9smpmtiduQDnKA4IG+bhBoMc4jRfWNMhoC0Otm0xVJ7k3Z2cDklT?= =?us-ascii?Q?01vtx9FShPERjseATQAEp/wS+24ngkk7/zGHxllfwcf88igl74AbV8o9hfB1?= =?us-ascii?Q?w3g5JRu6sBLsv2fraHeBiSUBefKXhfwVympepRg8+EX4ax/j3Bz3/XQguXxT?= =?us-ascii?Q?CEJzJjuf6DlwFy95Z8xsutTBSnwp4C7BGs7BL8DUG6eg64BuPmBvcq+JQymH?= =?us-ascii?Q?eo/iyi6Bi2g5QWtR2x2ADCxhMRiLeQtVXixdTEdJoeQ/WIt43JUW8TAbqI8C?= =?us-ascii?Q?y9ofih5eeIemD/ujPa3CEdQ6byg2NNmtPesvvSQc6aoBmH8b/yTfxuPUMXBN?= =?us-ascii?Q?i4kwZaYa42y1EvVf7OwY4eDM5ezcanPnwSg7AlFsX6SrstB/SlMnX/plxZ8J?= =?us-ascii?Q?7FVeMQ7Uzw5SRmM9UkMD835h7B0Qdq5dNKkJmuNB6hkMNwcGYZPC0vpp64C5?= =?us-ascii?Q?rslW9mG++255QxJ77bsqOABqqDUvnENzAybo0yNna6smmZtXtwJjRG5Z/cAg?= =?us-ascii?Q?lZOirUI49e1DYUcRJx1JwvC8rb7p10W6sAcjD5RysZ+M3s+FPtr2qxCSUS2E?= =?us-ascii?Q?z6nsy76ezijyVw/J7WTat+UWquHy196ESovfPrKFqRPA0c/vXxQ/ng8jBOGd?= =?us-ascii?Q?xKhhbMKspLleDl6+bD0z9ZQcSmfsajFM6oiaxAWsc3wHmA6F46H60CzU1qGB?= =?us-ascii?Q?DyQKFxsJIjtsZEoadXKrqrK+F+ob9y7Nb2nVX/M5ICF3g3WqYcfK/ExZNeB2?= =?us-ascii?Q?oidRyDWSr5Id5NEnYn7l9dx5MUfFU+rT6CiFUiRwG5vpYcD8kST16IvZlHMS?= =?us-ascii?Q?W1NHw3BHAQyBy30fEQ/pri3SD9f6QbVD6dmEGIRo8vYIobPF9l8VEU8QKWBO?= =?us-ascii?Q?ig4n3jijQe6KHas2QkB7Plz5/LejPBHvAcIzg9eBAjt/msumx8BBrSsQeB4Y?= =?us-ascii?Q?oepu5+NpNRUnYpp73Y+zsz36ftUIBh0qaR2WIbf2wbBV7UpUqE7dGccW+uoz?= =?us-ascii?Q?BZSRGULXuiVDHidIxxOllGDgNLlYYAlx/JYEqGtOtmRBRFwhr7X92edZOz3Y?= =?us-ascii?Q?TgQkEVnMgMAS+ef7uFcLBEo2Oovx6Tu1oVLVNJNvpolIo8bVr7J0iHpkgvb9?= =?us-ascii?Q?uizoSnSKwbUDN3gKnmKoUYC1wBQp0tHSYF0PKJy6?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: da72c9ec-cef3-438d-b61d-08de00f0e4a3 X-MS-Exchange-CrossTenant-AuthSource: DM4PR12MB6373.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Oct 2025 13:46:16.3805 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: cc+o2XOwOncvXrdcozCEe7nXOLwBIjt6o5tf1LuSI+hGXMTXRlrR+zaH8D/bJ8WwpW2rJHdnYlCynreMyWiaGQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB9006 On Tue, Sep 30, 2025 at 01:07:47PM -0500, Mario Limonciello (AMD) (kernel.org) wrote: > > > On 9/30/2025 11:45 AM, Yazen Ghannam wrote: > > Recent AMD node rework removed the "search and count" method of caching > > AMD root devices. This depended on the value from a Data Fabric register > > that was expected to hold the PCI bus of one of the root devices > > attached to that fabric. > > > > However, this expectation is incorrect. The register, when read from PCI > > config space, returns the bitwise-OR of the buses of all attached root > > devices. > > > > This behavior is benign on AMD reference design boards, since the bus > > numbers are aligned. This results in a bitwise-OR value matching one of > > the buses. For example, 0x00 | 0x40 | 0xA0 | 0xE0 = 0xE0. > > > > This behavior breaks on boards where the bus numbers are not exactly > > aligned. For example, 0x00 | 0x07 | 0xE0 | 0x15 = 0x1F. > > > > The bus numbering style in the reference boards is not a requirement. > > The numbering found in other boards is not incorrect. Therefore, the > > root device caching method needs to be adjusted. > > > > Go back to the "search and count" method used before the recent rework. > > Search for root devices using PCI class code rather than fixed PCI IDs. > > > > This keeps the goal of the rework (remove dependency on PCI IDs) while > > being able to support various board designs. > > > > Fixes: 40a5f6ffdfc8 ("x86/amd_nb: Simplify root device search") > > Was this a publicly reported failure? > > If so is there a link to LKML or a Bugzilla with the details of the failure > you can include here? > No, it was reported off-list. Thanks, Yazen