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Tue, 29 Sep 2026 13:57:59 +0000 Date: Tue, 29 Sep 2026 14:57:54 +0100 From: Bruce Richardson To: Stephen Hemminger CC: , Dmitry Kozlyuk , Thomas Monjalon , Ravi Kerur Subject: Re: [PATCH v2] eal: fail initialization if TSC frequency is zero Message-ID: References: <20260927195440.89193-1-stephen@networkplumber.org> <20260928231637.733450-1-stephen@networkplumber.org> <20260929064208.6c7453bb@phoenix.local> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260929064208.6c7453bb@phoenix.local> X-ClientProxiedBy: DU6P191CA0012.EURP191.PROD.OUTLOOK.COM (2603:10a6:10:540::12) To SN7PR11MB8066.namprd11.prod.outlook.com (2603:10b6:806:2df::18) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN7PR11MB8066:EE_|DS4PR11MB057924:EE_ X-MS-Office365-Filtering-Correlation-Id: 81456590-aabd-4bd2-5817-08df1e31abd4 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; ARA:13230040|366016|376014|1800799024|23010399003|10067099003|56012099006|11063799006|4143699003|6133799003|18002099003|22082099003; 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This might happen on a broken get_tsc_freq_arch() > > > or bad emulation in QEMU. > > > > > > If TSC hz is zero, log the error and propagate back to > > > fail rte_eal_init(). > > > > > > This fix doesn't need to go to stable since it is a purely > > > theoretical problem; we aren't getting divide by zero reports > > > from users. > > > > > > > How was this discovered? Is there a coverity issue id, or was it just AI > > discovered? > > It was part of review of pcapng timestamp calculation. > Kind of funny, AI spotted overflow (which I verified) in the code which > it had previously helped write. Then it was asking it self, > "what if TSC was 0". I didn't see how this could happen unless QEMU > had some broken CPU emulation. > > To me it seemed best to fail fast and die in a safer manner. > Agreed. You can add my ack, either for this version or a new version with the "set" function renamed as I suggest. Acked-by: Bruce Richardson