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arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Aug 2018 09:12:36.4984 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 069315ea-c3fa-454a-2091-08d5f921441b X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR08MB3289 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/08/18 08:53, Florian Weimer wrote: > On 08/03/2018 09:11 AM, Andrew Pinski wrote: >> Yes fix Links not to use memcpy on the framebuffer. >> It is undefined behavior to use device memory with memcpy. > > Some (de facto) ABIs require that it is supported, though.  For example, the POWER string functions avoid unaligned loads and stores for this > reason because the platform has the same issue with device memory.  And yes, GCC will expand memcpy on POWER to something that is incompatible > with device memory. 8-( > i think it's not reasonable to require libc memcpy to work on device memory. i think if device memory is exposed to regular userspace applications that should be fixed. > If we don't want people to use memcpy, we probably need to provide a credible alternative. > > Thanks, > Florian