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McKenney" , Randy Dunlap , Andrew Morton , Thomas Gleixner , "Maciej W. Rozycki" , Muchun Song , Viresh Kumar , Peter Zijlstra , Lu Baolu , Mike Rapoport , Will Deacon , xen-devel@lists.xenproject.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, Linux Kernel Mailing List , iommu , Christoph Hellwig References: <20210914151016.3174924-1-Roman_Skakun@epam.com> <7c04db79-7de1-93ff-0908-9bad60a287b9@suse.com> <84ef7ff7-2c9c-113a-4a2c-cef54a6ded51@suse.com> <20210915135321.GA15216@lst.de> From: Jan Beulich Message-ID: Date: Fri, 17 Sep 2021 11:52:10 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: PR0P264CA0178.FRAP264.PROD.OUTLOOK.COM (2603:10a6:100:1c::22) To VI1PR04MB5600.eurprd04.prod.outlook.com (2603:10a6:803:e7::16) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [10.156.60.236] (37.24.206.209) by PR0P264CA0178.FRAP264.PROD.OUTLOOK.COM (2603:10a6:100:1c::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4523.14 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?aWh1Qk45cENNVHNnTGcrUnRkYXpQRllDQ0NJZmZvR3dzbGIzTmUzRkdkTmc1?= =?utf-8?B?Y2lBck1PdjVNY3BGU24rVlJLSlEzNnNYd1Z1WHA3MUJ0RmoycTE2bVdPckZ2?= =?utf-8?B?ZWFFZTBZL2pTdEJpRlNmZHluMEhURVB4dzA5UFVRTU14UURHeUgzWHBxUlRh?= =?utf-8?B?b3R5cUgrM3NvWTVtcm5oQkpFelBKdUl0bkFQZldHNE1OczN4eEdLd0NNRS9K?= =?utf-8?B?Vmx1WXJrelVQVHlDWndHbER3aWZhdmlkTlByN0I3anRaMFFHVTk5alJiTWU1?= =?utf-8?B?SjhOUE9jN3owOVhQQTJUREtFQzdubENkRFpNYmxSa0Z0d3N4R0pWcy8rQW1C?= =?utf-8?B?a1p5N3NDdXNRdXZ6OGVoSVZEcitFclJWUHIweU1JclVpOFdUbk12Wm1UMXd3?= =?utf-8?B?cWtMZkpFcExIN0JNU0tEMHFlOHVTUTBHZ2lISEhEOTVHb3p5cmpzWm13OVhy?= =?utf-8?B?Q3d3WGdnV0hhd2pualBSRm1pR0tzOGVWdnBmOHdsUldHaml0UHY3OHphbTU2?= =?utf-8?B?Yk1jb29PQnpFRGFwS3VLTWM4c0VTR0o0Rnd3NEQveTluakpLTGovWkl5M3JN?= =?utf-8?B?aWQwY0d2SXZGenFLL0F1c3ZndHJtZ2FFYkt3VjdJNmsxODJCTGxuTGQzWTY5?= =?utf-8?B?RFE2ZWJEY0VyY1J0Tk9rV0pwd2JEbkp0ZzJJODJzNCtiRDJkV00rd2k4NnhH?= =?utf-8?B?cjRGWWU5RXRsU3M2dkxualBqK09pNXlhUXFleGs3Uk54T2U3aFR5eldMR3Av?= =?utf-8?B?ZUJkZ3dVTVZtTk5xZWNxSFQveVloZEFmUVFOemxwc3owSGxQVVhoRG9NM0I0?= =?utf-8?B?Q1lXQlpTMk1hN1RUWW5JUnBMUDRjeDV5bWw2UmxZenJWT0R6SW5qN1pTWEs2?= =?utf-8?B?TzhnUXIxMlU4MnVCNGxaNkdYcWQxN01TQ29hQUhuSFNxOGEzTm9ESGN3aWtk?= =?utf-8?B?UFFtbEd5UWlmVExKcStvTytuOHpyY3RYTzJ3QkkzdVYvTHFwYjBLenZUc09x?= =?utf-8?B?Unp1WXdJdTdiZEovdHlSdWs4QXo3VFM4UlRqWjMvWmZYRnNQUTBaUEd1Vm1Q?= =?utf-8?B?aEorMjlGbFJZNWpmYlhmNEJhQ2VTbmR5ZXU5eENzV1JMcmVhNFlhb0Z3SUpp?= =?utf-8?B?WnhraEcveVhKb2VFR0RDWHNwQXlJWFRIMDB1UFNuNjBMaEhiTGdURWNDTEVw?= =?utf-8?B?MUpyajE5dkI4MmthcFRidmo0SmxpQUJVL3NXUFJQbTRpTGQza1NhRVZnNjBk?= =?utf-8?B?VEhVblNUTnpDZ2pOaFlLdzNxQkFFbVpWZ0JvZWhtNGp0a1UvWHJLT3ZRWnhq?= =?utf-8?B?cUYzU2pTQVlaUjhnWGo0a1dGaTh4SklTbS81WVAxVkZobkdqc1JmeGpQbVlh?= =?utf-8?B?UTFxaXdjSTFwRnJCQ000N2RrTm83VGx6clczYkhFcWI3R3BEaVBJK3ZVQW50?= =?utf-8?B?Zy9uNjNJNU9wNEFJbjZXcW5JK3RrQ3h6ZnhEY1F6VHl1MC9MVGpWN3I2WlVw?= =?utf-8?B?UzBHVmlFaWt2UTlBRk1SV2pNVllBQmR3cTZvRUN6MzhDODFuUnJTVTQwSUZy?= =?utf-8?B?QXluT1NTR1poU2hZMXJ6eDQ5UHVaOC93V2lqcDFzOU5HVk5oN1hxNXgyaVRi?= =?utf-8?B?aGZkSkVkdHBsSXlvVDg5T2dBd25mWTV3bCtONTNaZnAxNzJNVFVtN0Qrd09M?= =?utf-8?B?WWt0UjJoN2RmeW9ZOFZYckdiRWN4N1krb3BwbXROU3g1ZjZLYkpoY21qYkZl?= =?utf-8?Q?tXdvUegyoB1lBi98nVCMJcsPYInAOshnLPJ5MAu?= X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: e7dda98c-565b-4ff6-e6d7-08d979c0d3bd X-MS-Exchange-CrossTenant-AuthSource: VI1PR04MB5600.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Sep 2021 09:52:14.4984 (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: qdlybJsY7Wdjq7223mSN8+JLrLBqmHTX8mLHVQUV8SHHaEKtzY/812DucDUvDwsb/d20AautVG5LUT35fL2u1Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0402MB3936 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17.09.2021 11:36, Roman Skakun wrote: > I use Xen PV display. In my case, PV display backend(Dom0) allocates > contiguous buffer via DMA-API to > to implement zero-copy between Dom0 and DomU. Why does the buffer need to be allocated by Dom0? If it was allocated by DomU, it could use grants to give the backend direct (zero-copy) access. Jan