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Message-ID: <6da822fb-e900-156b-334d-8bc573b74aee@suse.com> Date: Fri, 9 Sep 2022 14:14:04 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.1 Subject: Re: [PATCH] core-parking: fix build with gcc12 and NR_CPUS=1 Content-Language: en-US To: Julien Grall Cc: Andrew Cooper , George Dunlap , Stefano Stabellini , Wei Liu , "xen-devel@lists.xenproject.org" References: <1c23930f-e809-d623-18ec-599a0e983b7a@suse.com> From: Jan Beulich In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: AS9PR05CA0021.eurprd05.prod.outlook.com (2603:10a6:20b:488::17) To VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: VE1PR04MB6560:EE_|VI1PR0401MB2382:EE_ X-MS-Office365-Filtering-Correlation-Id: 6794fcb5-eaa5-447f-bb12-08da925ccac5 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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i < cur_idle_nums; ++i ) >> core_parking_cpunum[i] = core_parking_cpunum[i + 1]; >> >> complaining that the right hand side array access is past the bounds of >> 1. Clearly the compiler can't know that cur_idle_nums can only ever be >> zero in this case (as the sole CPU cannot be parked). >> >> Beyond addressing the immediate issue also adjust core_parking_init(): >> There's no point registering any policy when there's no CPU to park. >> Since this still doesn't result in the compiler spotting that >> core_parking_policy is never written (and hence is continuously NULL), >> also amend core_parking_helper() to avoid eventual similar issues there >> (minimizing generated code at the same time). > > Given that CONFIG_NR_CPUS is a build time option. Wouldn't it be better > to set CONFIG_CORE_PARKING=n and provide dummy helper for any function > that may be called unconditionally? That might be an option, yes; not sure whether that's really better. It's likely a more intrusive change ... Jan