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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?2xFJd3ssj7gnK9yxTdtZkc32xShdgIpex6W0QVLesLjxwn29RcUnMXiUKgt6?= =?us-ascii?Q?sc351IU+Wn//ocsvCRUCpXI/yUE/eYslWv/NBeAMl5iEwUCoa+IYbdGOzTHc?= =?us-ascii?Q?695ciKpE5ecqW0unNY+HDcRFS78uw7/h1XIO/LGF8+X1VD+x/U4oSMjRjF90?= =?us-ascii?Q?pm/qLQ3qKai358DOevVfdAquxpW1CAugmUj/byBfq/t6ZZN473j0umqXsO5r?= =?us-ascii?Q?7ikPx/uyyg6OP66uStbdtIM/EufPgSEeSLxUkAA3j+PMcvgJI58dhgEPKnY/?= =?us-ascii?Q?TR0mxDxc1/gXlrwCQ1FEdiUTd7q5INf7H8jTKcgkqQO7KJkJpfJcD8mIqxHC?= =?us-ascii?Q?Au/YqRWH7ejC/NXO1W9IdoW4OWJ/zD16qQODcPV7A2dl7l+OcDSaadtbmKBq?= =?us-ascii?Q?+SeCk35+aoqGkQYbaI+Mh/u8GIxqYztT8ED97N++y88kRyS3VrbULUHrXiLf?= =?us-ascii?Q?LnFokLUjlgypBaiYQAhhcRorhMCiZqFo21+n6c6k4b/XpjEJl9lJwC0+K94g?= =?us-ascii?Q?EqB2ZITF/ZV7bRVnvuiE7RNtv7n/Cw5rhd+v0zOAvlVwraSPRsCtUHtFMF12?= =?us-ascii?Q?qaLBdYu/5ECJR3LQhO+5MM8+hOdJJPamSSe+8in4txyTpE03NzJB4pYH8Ay5?= =?us-ascii?Q?RGewXtmTd/qxlqK8DCzvUk7dueTWhbh1jGe+q0zjy4lK47wrnE1YowOXNRQ+?= =?us-ascii?Q?9tKllN1OVkk9IX5pd3Ec7uYwTqJcYysZSoq7FTwD3PgulUOo4p1tNuppB3NK?= =?us-ascii?Q?cRe1QvKbYoddNyVX5CY5RjZSjjXK+50+4306gW8cnI3/e99YQfNEhCrc5sFm?= =?us-ascii?Q?fR7VgIMQYSscdEQ74op2CXnmZ3wKuxfD2ZNtg0j82n8YqYJp3MeTn11N6FTv?= =?us-ascii?Q?88yPfgpr8kTy1Zj9gnnjnEvTIstiOGspSg4+1E4BMN/tHLCvw0k8lnsvjE0S?= =?us-ascii?Q?i/FXHe4zUl2BYOPR76qYTXKTyH3nHr0OhLVyeXUIM2Ohzk3qhmsiLSCdsZdN?= =?us-ascii?Q?M9FW0QhmLag3iPjfepoK4wRICe16zHQK75jRZoI3uCwW5Q2/TCg9//1P5FLJ?= =?us-ascii?Q?VVJA+GBqdMuCpfK8vfvCpbaCmxhZTQ4GOuAmvWq/2C4F06//oj0CZKH3hKsp?= =?us-ascii?Q?V+ruy7qrhoRduNbxgMOXM89pcZlvhMSQR7oh0PLCIpgoXXPEANObHCVx1fke?= =?us-ascii?Q?nqDApz4eSadjCurCOPZShKZPZ6XpbP2e/2v5JOuGnh5Ve90ypXSM8FvZzcuG?= =?us-ascii?Q?1c+9KGW8F4/2cp/GH981QzGPFjxWcdSg41vGHRbn0Y743KfzN+PgtAJzj6uF?= =?us-ascii?Q?D2Y5hBbD0PuOQN4TOyEmTPmlM3+o2meFVyVkvTZRH9MUznfX/rn1cDFrk6jz?= =?us-ascii?Q?AF9bbF/DtrpiBicYYVUzhgQzy9MPHOjAiAjIWRTkJ3lbHj5exXFwrdbXL/CT?= =?us-ascii?Q?uC/qbJd23E8bR1g6BpXKAiALzGs7tm4pLwdBfi7ws5D97f4tFLwRhmMhStfR?= =?us-ascii?Q?YWGok8723XBddpJocSSRDYiZFJkSgUOrE/0KAhenvFsmBfFZYLkb+9pb+KE5?= =?us-ascii?Q?mOG+ELOAt8wPI5Po7LM=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f77e7518-f1e7-4f78-d946-08de26ab2f48 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3613.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Nov 2025 14:03:01.4409 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: RWGmZkkGf7Rc7UPCXzH/r0Mm/RL1OzNxTFfrBdl1l4VGouDMArLy26tMGeTgWFSO X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN6PR12MB8542 On Tue, Nov 18, 2025 at 01:21:34PM +0200, Mike Rapoport wrote: > On Mon, Nov 17, 2025 at 11:22:54PM -0500, Pasha Tatashin wrote: > > > You can avoid that complexity if you register the device with a different > > > fops, but that's technicality. > > > > > > Your point about treating the incoming FDT as an underlying resource that > > > failed to initialize makes sense, but nevertheless userspace needs a > > > reliable way to detect it and parsing dmesg is not something we should rely > > > on. > > > > I see two solutions: > > > > 1. LUO fails to retrieve the preserved data, the user gets informed by > > not finding /dev/liveupdate, and studying the dmesg for what has > > happened (in reality in fleets version mismatches should not be > > happening, those should be detected in quals). > > 2. Create a zombie device to return some errno on open, and still > > study dmesg to understand what really happened. > > User should not study dmesg. We need another solution. > What's wrong with e.g. ioctl()? It seems very dangerous to even boot at all if the next kernel doesn't understand the serialization information.. IMHO I think we should not even be thinking about this, it is up to the predecessor environment to prevent it from happening. The ideas to use ELF metadata/etc to allow a pre-flight validation are the right solution. If we get into the next kernel and it receives information it cannot process it should just BUG_ON and die, or some broad equivalent. It is a catastrophic orchestration error, and we don't need some fine grain recovery or userspace visibility. Crash dump the system and reboot it. IOW, I would not invest time in this. Jason