Multiple buffers with io_uring_prep_recvmsg_multishot

[ollie-etl]

Does io_uring_prep_recvmsg_multishot support receiving into multiple buffers, i.e, when msghdr.msg_iovlen > 1. I can't see any tests or examples based on this, but also don't see any prose prohibiting this.

[isilence]

Multishot receive requests work only with provided buffers, see IOSQE_BUFFER_SELECT, which taking out provided buffers from the group specified in sqe->buf_group and keep filling them in with received data. And so they don't take any real iovec, but rather some additional information disguised as such. IIRC, for non-multishot msg_iovlen should be strictly 1, and only iovec[0].iov_len is used to figure out the asked receive size. Don't remember for multishot, but it probably needs msg_iovlen == 0.

In short, it doesn't take a normal iovec, and it already can fill multiple buffers that it selects from the specified provided buffer pool.