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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BN7PR02MB4148.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-CrossTenant-Network-Message-Id: c41ed9ca-c6de-477b-d3cb-08dd77704729 X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Apr 2025 14:10:26.9867 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR02MB9105 X-Rspamd-Queue-Id: 6CE8A40018 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: qy58bcrpysbhr99eq1fsga33f94b8nrc X-HE-Tag: 1744207830-441443 X-HE-Meta: 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 mhksTJ+Y NPohSMVwcJpEpjIXoqRfNrmf3dmvSCFy9t3V/HZ3nc32wzetJIPoaQOoGgwXBhCZPRP+vlColnzoqPttIxwBJt7OE3NkJ5DXqkLdxABs281RgL/X26HPzYu8sAc9VuIdY/mmxd2KHHQUOwat9Yxq+/iNT/A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.002703, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Christoph Hellwig Sent: Wednesday, April 9, 2025 3:50 AM >=20 > On Tue, Apr 08, 2025 at 11:36:44AM -0700, mhkelley58@gmail.com wrote: > > From: Michael Kelley > > > > Export vmf_insert_mixed_mkwrite() for use by fbdev deferred I/O code, >=20 > But they are using this on dma coherent memory, where you can't legally > get at the page. As told last time you need to fix that first before > hacking around that code. Hmmm. What's the reference to "as told last time"? I don't think I've had this conversation before. For the hyperv_fb driver, the memory in question is allocated with a direct= call to alloc_pages(), not via dma_alloc_coherent(). There's no DMA in this scen= ario. The memory is shared with the Hyper-V host and designated as the memory for the virtual framebuffer device. It is then mapped into user space using= the mmap() system call against /dev/fb0. User space writes to the memory are eventually (and I omit the details) picked up by the Hyper-V host and displ= ayed. Is your point that memory dma_alloc_coherent() memory must be treated as a black box, and can't be deconstructed into individual pages? If so, that = makes sense to me. But must the same treatment be applied to memory from alloc_pages()? This is where I need some education. >=20 > > which can be built as a module. For consistency with the related functi= on > > vmf_insert_mixed(), export without the GPL qualifier. >=20 > No. All advanced new Linux functionality must be _GPL. Don't try to > sneak around that. No problem. Just trying to be consistent, not sneak around anything. Thanks, Michael