On Fri, Jun 13, 2025 at 09:33:55AM +0000, wangtao wrote: > > > > > On Mon, Jun 09, 2025 at 09:32:20AM +0000, wangtao wrote: > > > Are you suggesting adding an ITER_DMABUF type to iov_iter, > > > > Yes. > > May I clarify: Do all disk operations require data to pass through > memory (reading into memory or writing from memory)? In the block layer, > the bio structure uses bio_iov_iter_get_pages to convert iter_type > objects into memory-backed bio_vec representations. > However, some dmabufs are not memory-based, making page-to-bio_vec > conversion impossible. This suggests adding a callback function in > dma_buf_ops to handle dmabuf- to-bio_vec conversion. bios do support PCI P2P tranfers. This could be fairly easily extended to other peer to peer transfers if we manage to come up with a coherent model for them. No need for a callback.
