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Thu, 20 Feb 2025 00:13:39 -0800 (PST) Received: from archie.me ([103.124.138.155]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-220d5349634sm114661275ad.31.2025.02.20.00.13.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Feb 2025 00:13:38 -0800 (PST) Received: by archie.me (Postfix, from userid 1000) id C04B84208FB6; Thu, 20 Feb 2025 15:13:35 +0700 (WIB) Date: Thu, 20 Feb 2025 15:13:35 +0700 From: Bagas Sanjaya To: Mina Almasry , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Donald Hunter , Jonathan Corbet , Andrew Lunn , Jeroen de Borst , Praveen Kaligineedi , Shailend Chand , Kuniyuki Iwashima , Willem de Bruijn , David Ahern , Neal Cardwell , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , Stefan Hajnoczi , Stefano Garzarella , Shuah Khan , sdf@fomichev.me, asml.silence@gmail.com, dw@davidwei.uk, Jamal Hadi Salim , Victor Nogueira , Pedro Tammela , Samiullah Khawaja Subject: Re: [PATCH net-next v4 5/9] net: add devmem TCP TX documentation Message-ID: References: <20250220020914.895431-1-almasrymina@google.com> <20250220020914.895431-6-almasrymina@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="j3ck8zPX3Nllt0fQ" Content-Disposition: inline In-Reply-To: <20250220020914.895431-6-almasrymina@google.com> --j3ck8zPX3Nllt0fQ Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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 si= milar > +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 int= erface > +the dma-buf has been bound to via SO_BINDTODEVICE. > + > + setsockopt(socket_fd, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifnam= e) + 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. --=20 An old man doll... just what I always wanted! - Clara --j3ck8zPX3Nllt0fQ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQSSYQ6Cy7oyFNCHrUH2uYlJVVFOowUCZ7bkKQAKCRD2uYlJVVFO o2s0AQCqEcmu39fAQOLMTwOYkn6NbqUyjT/e6q34LK5lpFeB7gEAw4iw+0dFGzFm S+/rpVCO8Pfw8Mt4Xg/RDLmSlwuOhgs= =QlMN -----END PGP SIGNATURE----- --j3ck8zPX3Nllt0fQ--