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Message-ID: Date: Fri, 28 Mar 2025 10:13:45 +0100 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] xen/char: implement suspend/resume calls for SCIF driver To: Julien Grall , Mykola Kvach , xen-devel@lists.xenproject.org Cc: Volodymyr Babchuk , Stefano Stabellini , Bertrand Marquis , Oleksandr Andrushchenko , Mykola Kvach References: <800acb5c8447153e6c451c8df316ff678fbb4087.1743114879.git.mykola_kvach@epam.com> From: "Orzel, Michal" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR0P281CA0180.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:b4::10) To BN9PR12MB5273.namprd12.prod.outlook.com (2603:10b6:408:11e::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN9PR12MB5273:EE_|MW4PR12MB7141:EE_ X-MS-Office365-Filtering-Correlation-Id: 78bbda1e-97f5-45f5-0b56-08dd6dd8d9f3 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|366016; 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They will be used by but the caller > is not used on Arm yet. So you are saying the code there is not MISRA > compliant? If so, is this reported by ECLAIR? NS also works for x86 that has suspend feature. SCIF only works for Arm that does not have suspend feature. Neither NS nor SCIF are enabled in ECLAIR. We have enabled MISRA 2.1 rule about unreachable code (suspend is example of unreachable because it *cannot* be executed), but it's not clean i.e. gating. > > Regardless that, I don't think the full suspend/resume series would > help. AFAIR, the caller will be protected with a config (SUSPEND > something). So IIUC your definition, this code will still be "dead code" > in certain config. Therefore are you suggesting to protect everything > suspend specific code with SUSPEND? I'd say so, yes. > > If the answer is yes, how about introducing the SUSPEND config now? This > would allow to get some of the code merged in advance. Better this than nothing. But in case of this patch, why would we take it anyway without suspend feature? I'd prefer to add SUSPEND config and protect existing code i.e. NS that can work on x86 but not on Arm, etc. ~Michal