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pr=C Message-ID: <7ef46d06-7674-40bf-816c-71f6935394fb@amd.com> Date: Tue, 18 Aug 2026 17:10:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/3] time: add "NOW() good" indicator To: Jan Beulich , "xen-devel@lists.xenproject.org" CC: Andrew Cooper , Julien Grall , Stefano Stabellini , Anthony PERARD , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Teddy Astie , Bertrand Marquis , Volodymyr Babchuk , Oleksii Kurochko References: From: "Orzel, Michal" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN1PEPF00004681:EE_|CH3PR12MB8401:EE_ X-MS-Office365-Filtering-Correlation-Id: bb0ff625-63fd-4900-f442-08defd3ae31d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|1800799024|376014|82310400026|7416014|23010399003|10067099003|56012099006|11063799006|4143699003|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: pKDtnnffxLHO5nDFbb8Xcee0PaNUXf8diLRVbNMAJVjbd4lPfn9iiut/eWfrxfTjwdMQ7G4sPOypzuHCys8Ua2jCGLLuEsDYUaky893XEhf/sAF3N4t6JmlpOPTmRENKRp5XQtP5/74hQ+kXO4BAVHs0gn1JmKkIcapGHyq8wuzEA+yYiU71dbG91qXMzjCPO/TKx7WcV5SOZSvIfjoZcY+upO/v6T4KWovUAETrYQKq1xSci/Qt2u1l2KBbPPDzKsJFWbt8JD5zXN/CLgwunWKCjRKuWnGdNngOdECqy/z621zTyMzkvl+zTXmD1tE5sQ4SrMqzI9tCcDZ7116XOsr3yHflgTJV9txZkq2M5mT6ZXa8SBk3lmGO0FsNdTuSICnW8G1WEQIxflo8fPhRiFUdhiA070PPGDNjo61tEFKG9/6qlX7r5a37RWJB1VBm X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Aug 2026 15:10:49.3032 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: bb0ff625-63fd-4900-f442-08defd3ae31d X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN1PEPF00004681.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8401 X-purgate-ID: tlsNG-4011c0/1787065855-520C1CFC-597ADFBD/0/0 X-purgate-type: clean X-purgate-size: 853 On 30-Jun-26 16:06, Jan Beulich wrote: > printk_start_of_line() checks for a value of 0 right now. In order to be > able to have NOW() return at least monotonically increasing values, that > needs replacing by an explicit indicator. > > Signed-off-by: Jan Beulich Reviewed-by: Michal Orzel > --- > Arm and RISC-V may want to consider whether their initial get_cycles() > can't be moved yet earlier, such that the indicator also can be set > yet earlier. On Arm, get_cycles() just reads a system register and it could be moved earlier. That said, is there any rule as to what should actually be considered a start of time (i.e. the boot_count value)? At the moment, this denotes the moment where the time driver is set up in preinit_xen_time() after validating the frequency. ~Michal