On 2/6/23 07:00, Ming Lei wrote:
4) DMA - DMA requires physical memory address, UBLK driver actually has block request pages, so can we export request SG list(each segment physical address, offset, len) into userspace? If the max_segments limit is not too big(<=64), the needed buffer for holding SG list can be small enough. - small amount of physical memory for using as DMA descriptor can be pre-allocated from userspace, and ask kernel to pin pages, then still return physical address to userspace for programming DMA - this way is still zero copy
Would it be possible to use vfio in such a way that zero-copy functionality is achieved? I'm concerned about the code duplication that would result if a new interface similar to vfio is introduced. In case it wouldn't be clear, I'm also interested in this topic. Bart.
