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mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none Authentication-Results: xen.org; dkim=none (message not signed) header.d=none;xen.org; dmarc=none action=none header.from=suse.com; Subject: Re: [PATCH 01/11] xen: reserve flags for internal usage in xen_domctl_createdomain To: Penny Zheng , xen-devel@lists.xenproject.org, sstabellini@kernel.org Cc: Bertrand.Marquis@arm.com, Wei.Chen@arm.com, Julien Grall References: <20210923031115.1429719-1-penny.zheng@arm.com> <20210923031115.1429719-2-penny.zheng@arm.com> <7da75d7c-5640-305d-d742-d64b8c219949@xen.org> From: Jan Beulich Message-ID: <60d813f7-a756-172c-999d-44f81504e268@suse.com> Date: Tue, 28 Sep 2021 14:05:39 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 In-Reply-To: <7da75d7c-5640-305d-d742-d64b8c219949@xen.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: PR0P264CA0260.FRAP264.PROD.OUTLOOK.COM (2603:10a6:100::32) To VI1PR04MB5600.eurprd04.prod.outlook.com (2603:10a6:803:e7::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: f305928e-7e1c-4d0f-2d05-08d982784ae1 X-MS-TrafficTypeDiagnostic: VI1PR0401MB2334: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:9508; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?VDdzS0M1WmkyU255Q2JVOUNuaDZMdzRlOGlTRWd1Q0dCUStxVXVSYlR4d0wr?= =?utf-8?B?VVVDSU85TC81ZTExS3hnWXdvVEJKYmZMei95anJkcUpPR0QwZFN5V09DVGhH?= =?utf-8?B?Z3BoTmdXcnkxdGxFeExPK2xpaHpXNC96NmlDN0x0VkEzTVRPVVBXRk40ajQx?= =?utf-8?B?OGFhY0Y1WG9zVUw4RFpzYjdwVWs2dkdSa0U4NnFsMHVDaUV1TmpyeDIzVEx3?= =?utf-8?B?ZFRmd0FIcEdBU3J2cW5QSnVTWjA3ZWtZZ3FLRHg4U1ZnczUxL1FuREk2SUhS?= =?utf-8?B?QzUwQTN6a0dOTnEwRXlLNW1QdzNLeWxVUFV3d0RzTW5qb0VjUU1Cb2FqK00r?= =?utf-8?B?U3BDOCt3RW1oWHhuSmt6Q1ZxbFlHWWxSNDIyTXZMNWkwcU1ITDZsYWN1Rm9r?= =?utf-8?B?WnNxYWlmcDJrMHVmRlowS3FZc2lTOHY3VnlxbVh5ZUlpcTJQeVJEU0NRcXZ6?= =?utf-8?B?T3FodnA5cEgzMnk0cmJFT0xyWnJRcjlIakJ2VHR3S2VLemJQdGhXTUtxczZU?= =?utf-8?B?WVk3bjF6UlBvU2ZmcUx3R1MyMjJBQktGa0tXZDBSV3pmVjNkbEQ2VVY1dGox?= =?utf-8?B?OE9nc0VDdmNFSzh2RU43TFdhQ0tJaTJ6NWV6ZzZGNWJ5RWp5eVJURmFBOGRt?= =?utf-8?B?SHY4djJYVGowbVQ1VkNoZkZCOHlQYVFrZFRtbEEwbldJdVdEb044V1pNTktK?= =?utf-8?B?SVhCSEx6YXJtb3k3UUxKWlA2bXlObm1JY2pNRGxsS0JRZFdiaW4valp6UGtG?= =?utf-8?B?N2NzSVNERkVDL0JSNjBEWXM0UHYxVElISk9tancyWVQ3L0FsVFZmZVNGdVhw?= =?utf-8?B?dEdDRnBDWEJsYW9iSHB3d3hZcmkvcnVsUyt1SGJMYjhBQVltelRqNHhMTHZX?= =?utf-8?B?VUpXSXpFMnFENkdjZHJBck5BY3hGdCtZYnEvcjhGVlhWbzFHbmhiTVUzOFls?= =?utf-8?B?ZklkeXYwYzl2cDBGV1B5Nk1RYnNzc1NITlFmU2tjU3k2Ny9DSEx6M29nTTB0?= =?utf-8?B?QVI1dE9iM2svTytMY0hnTW9sOElqK2RSd0Y3QjF0RWxPNlJHT1FFdUJvUWFE?= =?utf-8?B?dUtzTC80SEFHbHlKVzRtbkRkN1cvYnh5U0ZCZkhxQmFTcTZrOVd6a2hOWU05?= =?utf-8?B?ejFxZWwxSDZuVVVjSGRQVW5LaXFWV0NLU29qTE55SHlac2VaSVdZMzlFSCs0?= =?utf-8?B?YVBSb1FYRGtuNDZaNkJIYUdtMjhaUTVrYndPdGFTRDBHa3Z3c3dMY0xFNWw0?= =?utf-8?B?MjdqS1BJTFplUi9ldmIzK1RGNkdrSjFKdWYwTTg5N1pETXJOMzZqWExLRk16?= =?utf-8?B?cHF5RERidUp1ZXBId1B0UUhRaGdNd0VRZ2VwbGlUaDIwbytYeW5hRVc4UG1C?= =?utf-8?B?MDFGdlZJdnJjWFh1RHJpTUFxczJ2Tm5CZ3BvL0tXMEtQQjdtSkR2YVRZTTh3?= =?utf-8?B?M2xVaEc4UC9sdSthWlJaS25vMHkwNEFOY3NwNU5WTStCNXB3NERRcEIrRnAz?= =?utf-8?B?ODI3aForRXZOOWpKQUx0OUdyejdoMU5MdHlWc1pJd2sxZ0JFWkRUTDJDRlJo?= =?utf-8?B?azVVRDhqZmF2Mm9PbldKZFFYdlcydENBUFRXS2ZNL1JLcDdoQzNRS2tZTitR?= =?utf-8?B?UWNudkgwaXo1Z1c4dDVvSlFTTklqSzFwM0dJZWs5YTZVS0FKM3p1ZlpiTGFR?= =?utf-8?B?TThKSmM1bzE4U3hOQURaQS84NnF5RklycTZ3UUNzQitiRW5hbCtsb1BMTUx0?= =?utf-8?Q?ntZyBure7mGITyM+dCbIs0Xh0OiWE64A2f+raDR?= X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: f305928e-7e1c-4d0f-2d05-08d982784ae1 X-MS-Exchange-CrossTenant-AuthSource: VI1PR04MB5600.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Sep 2021 12:05:41.5362 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: snkNe2fw3KAJVHnNbmCqiMOALWh2PZVai/RJp7pBb5ZH1bd6SZUmyKo8Yn8J7YZ8PXQPolUk1m5ILUcimbAx4w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0401MB2334 On 23.09.2021 11:54, Julien Grall wrote: > On 23/09/2021 08:11, Penny Zheng wrote: >> From: Stefano Stabellini >> >> We are passing an extra special boolean flag at domain creation to >> specify whether we want to the domain to be privileged (i.e. dom0) or >> not. Another flag will be introduced later in this series. >> >> Reserve bits 16-31 from the existing flags bitfield in struct >> xen_domctl_createdomain for internal Xen usage. > > I am a bit split with this approach. This feels a bit of a hack to > reserve bits for internal purpose in external headers. But at the same > time I can see how this is easier to deal with it over repurposing the > last argument of domain_create(). I actually have trouble seeing why that's easier. It is a common thing to widen a bool to "unsigned int flags" when more than one control is needed. Plus this makes things needlessly harder once (in the future) the low 16 bits are exhausted in the public interface. Jan