Re: [PATCH net-next v4 5/9] net: add devmem TCP TX documentation

On Thu, Feb 20, 2025 at 02:09:10AM +0000, Mina Almasry wrote:

+The user application must use MSG_ZEROCOPY flag when sending devmem TCP. Devmem +cannot be copied by the kernel, so the semantics of the devmem TX are similar +to the semantics of MSG_ZEROCOPY.

• setsockopt(socket_fd, SOL_SOCKET, SO_ZEROCOPY, &opt, sizeof(opt));

+It is also recommended that the user binds the TX socket to the same interface +the dma-buf has been bound to via SO_BINDTODEVICE.

• setsockopt(socket_fd, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname) + 1);

Wrap both setsockopts above in literal code-block (just like other snippets for consistency).

+The user should create a msghdr where,

+iov_base is set to the offset into the dmabuf to start sending from. +iov_len is set to the number of bytes to be sent from the dmabuf.

Should above be bullet list?

Thanks.