This series adds net_rtap, an experimental poll mode driver that uses Linux io_uring for asynchronous packet I/O with kernel TAP interfaces.
Like net_tap, net_rtap creates a kernel network interface visible to standard tools (ip, ethtool) and the Linux TCP/IP stack. From DPDK it is an ordinary ethdev. Motivation ---------- This driver started as an experiment to determine whether Linux io_uring could deliver better packet I/O performance than the traditional read()/write() system calls used by net_tap. By posting batches of I/O requests asynchronously, io_uring amortizes system call overhead across multiple packets. The project also served as a testbed for using AI tooling to help build a comprehensive test suite, refactor code, and improve documentation. The result is intended as an example for other PMD authors: the driver has thorough unit tests covering data path, offloads, multi-queue, fd lifecycle, and more, along with detailed code comments explaining design choices. Why not extend net_tap? ----------------------- The existing net_tap driver was designed to provide feature parity with mlx5 when used behind the failsafe PMD. That goal led to significant complexity: rte_flow support emulated via eBPF programs, software GSO implementation, and other features that duplicate in user space what the kernel already does. net_rtap takes the opposite approach — use the kernel efficiently and let it do what it does well. There is no rte_flow support; receive queue selection is left to the kernel's native RSS/steering. There is no software GSO; the driver passes segmentation requests to the kernel via the virtio-net header and lets the kernel handle it. The result is a much simpler driver that is easier to maintain and reason about. Given these fundamentally different design goals, a clean implementation was more practical than refactoring net_tap. Acknowledgement --------------- Parts of the test suite, code review, and refactoring were done with the assistance of Anthropic Claude (AI). All generated code was reviewed and tested by the author. Requirements: - Kernel headers with IORING_ASYNC_CANCEL_ALL (upstream since 5.19) - liburing >= 2.0 Known working distributions: Debian 12+, Ubuntu 24.04+, Fedora 37+, SLES 15 SP6+ / openSUSE Tumbleweed. RHEL 9 is not supported (io_uring is disabled by default). v5 - revised, renamed and expanded from the v4 ioring PMD - more complete testing and dependency handling Stephen Hemminger (10): net/rtap: add driver skeleton and documentation net/rtap: add TAP device creation and queue management net/rtap: add Rx/Tx with scatter/gather support net/rtap: add statistics and device info net/rtap: add link and device management operations net/rtap: add checksum and TSO offload support net/rtap: add link state change interrupt net/rtap: add multi-process support net/rtap: add Rx interrupt support test: add unit tests for rtap PMD MAINTAINERS | 7 + app/test/meson.build | 1 + app/test/test_pmd_rtap.c | 2044 ++++++++++++++++++++++++ doc/guides/nics/features/rtap.ini | 25 + doc/guides/nics/index.rst | 1 + doc/guides/nics/rtap.rst | 101 ++ doc/guides/rel_notes/release_26_03.rst | 6 + drivers/net/meson.build | 1 + drivers/net/rtap/meson.build | 28 + drivers/net/rtap/rtap.h | 100 ++ drivers/net/rtap/rtap_ethdev.c | 908 +++++++++++ drivers/net/rtap/rtap_intr.c | 267 ++++ drivers/net/rtap/rtap_rxtx.c | 784 +++++++++ 13 files changed, 4273 insertions(+) create mode 100644 app/test/test_pmd_rtap.c create mode 100644 doc/guides/nics/features/rtap.ini create mode 100644 doc/guides/nics/rtap.rst create mode 100644 drivers/net/rtap/meson.build create mode 100644 drivers/net/rtap/rtap.h create mode 100644 drivers/net/rtap/rtap_ethdev.c create mode 100644 drivers/net/rtap/rtap_intr.c create mode 100644 drivers/net/rtap/rtap_rxtx.c -- 2.51.0
