Hello, How do you think about adding a new callback function which makes allocator for vb2 fill the reserved field in v4l2_buffer as below. As-Is: VIDIOC_QUERYBUF -> v4l2_m2m_querybuf -> vb2_querybuf -> __fill_v4l2_buffer To-Be: VIDIOC_QUERYBUF -> v4l2_m2m_querybuf -> vb2_querybuf -> __fill_v4l2_buffer + vb2_mem_ops.fill_v4l2_buffer I want to use the reserved field as for process unique key to share the buffer between inter-process. When I want to send a buffer which is allocated by A device to other process, I want to get the process unique key from VIDIOC_QUERYBUF. The process which gets the process unique key from other process will make user virtual address from the key in any other way. And then send it to B device using QBUF with USERPTR buffer type. How do you think about this concept ? Process A Process B 1. VIDIOC_QUERYBUF to get the process unique key 2. VIDIOC_DQBUF 3. Send the process unique key to Process B -----------------------------------> Process unique key 4. Make a user virtual address from the process unique key 5. VIDIOC_QBUF with user virtual address 6. find the paddr or device address from the user virtual addr. in videobuf2 7. H/W operation. SCM_RIGHTS can be the solution for inter-process buffer sharing. http://blog.toidinamai.de/en/programming/SCM_RIGHTS But it has risk that other process can also control the device using the shared file descriptor. So I'm trying to make another solution. Best regards, -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html