On Tue, Jul 06, 2021 at 12:44:49PM +0300, Oded Gabbay wrote:

quoted

quoted

+     /* In case we got a large memory area to export, we need to divide it
+      * to smaller areas because each entry in the dmabuf sgt can only
+      * describe unsigned int.
+      */

Huh? This is forming a SGL, it should follow the SGL rules which means
you have to fragment based on the dma_get_max_seg_size() of the
importer device.

hmm
I don't see anyone in drm checking this value (and using it) when
creating the SGL when exporting dmabuf. (e.g.
amdgpu_vram_mgr_alloc_sgt)

For dmabuf the only importer is RDMA and it doesn't care, but you
certainly should not introduce a hardwired constant instead of using
the correct function.

Jason