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Message-ID: <4cbaaf12-bd11-ca04-eed1-f8848290a692@suse.com> Date: Wed, 19 Apr 2023 08:28:16 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 Subject: Re: [PATCH v5 00/12] SVE feature for arm guests Content-Language: en-US To: Julien Grall , Bertrand Marquis , Luca Fancellu Cc: Xen-devel , Wei Chen , Stefano Stabellini , Volodymyr Babchuk , Andrew Cooper , George Dunlap , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Nick Rosbrook , Anthony PERARD , Juergen Gross , Christian Lindig , David Scott , =?UTF-8?Q?Marek_Marczykowski-G=c3=b3recki?= , Henry Wang , Community Manager References: <20230412094938.2693890-1-luca.fancellu@arm.com> <08BE4F94-C4B5-4B05-AD92-61C5C5D24F39@arm.com> From: Jan Beulich In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR3P281CA0210.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:a5::19) To VE1PR04MB6560.eurprd04.prod.outlook.com (2603:10a6:803:122::25) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: VE1PR04MB6560:EE_|AM7PR04MB7128:EE_ X-MS-Office365-Filtering-Correlation-Id: 71040519-5356-4ece-d47d-08db409f43dc X-LD-Processed: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba,ExtFwd X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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This would at least keep SVE enabled if a VM depends on it and could simplify >> some of the handling by using 2048 to use the maximum supported size. > > My concern with this approach and the third one is the user may take > some time to realize the problem in the xl.cfg. So... > >> >> - coherently stop if the parameter value is not supported (including if sve is >> not supported) > > ... this is my preferred approach because it would be clear that the > value passed to Xen is bogus. I did say earlier on that this comes with its own downside of preventing boot to complete for no real reason. It's all Arm code, so you're fine to ignore me, but in similar situations elsewhere (sorry, don't recall a concrete example off the top of my head) we've aimed to allow the system to boot, for the admin to then take corrective action if/as needed. Jan