Zephyr 4.5 Released With Massive Hardware Support and Networking Upgrades
Zephyr 4.5 marks a record-breaking release featuring new architecture support, significant networking throughput gains, and a new multimedia pipeline subsystem.
Zephyr 4.5 is out with contributions from more than 1,200 people, setting a record for the project. Over half of the commits come from drivers and hardware support.
The update adds Infineon TriCore, used in AURIX automotive microcontrollers, and Qualcomm Hexagon, a DSP architecture. QEMU targets qemu_tc3x, qemu_tc4x, and qemu_hexagon let you try them without physical hardware, though the TriCore QEMU and Hexagon toolchain require separate setup from the Zephyr SDK.
In networking, IP stack optimizations in the zperf loopback benchmark raise TCP throughput by up to 21% and UDP throughput up to 12%. UDP gains hit 7 to 12% on x86 and Cortex-M3, and 1 to 3.5% on RISC-V. TCP selective acknowledgment is now on by default. The stack gains QUIC transport, HTTP/3 for the HTTP server, an SSH server and client, IPv4 forwarding with NAT and connection tracking, DHCPv6 prefix delegation, and IPv6 router advertisements. You can manage forwarding rules with net iptable. Zephyr also acts as a Model Context Protocol server, enabling AI agents to discover and call tools on a board via a new devicetree class: key.
The experimental Multimedia Pipeline subsystem brings a GStreamer-style model to microcontrollers without copying buffers. West can now generate SPDX 3.0 SBOMs serialized as JSON-LD when requested with west spdx -d build --spdx-version 3.0. A revamped hardening tool checks configurations against Security Working Group recommendations, maps them to CWEs, and fails CI builds on regressions. A new FIDO2 subsystem allows a device to act as a passkey authenticator over USB or BLE.
The release adds the ZASSERT() macro, heap error detection via CONFIG_SYS_HEAP_SANITIZER_ASAN on native_sim and CONFIG_SYS_HEAP_KASAN on real targets, a tracing terminal viewer, a shell, an ITM backend, and Perfetto export. Crashed devices can send coredumps over UDP. Six driver classes arrive: buzzer, clock monitor, DALI, LIN, MUX, and pulse IO. Kernel tests on an STM32F412 board ran 3 to 15% faster than on version 4.4 in Thread-Metric runs. The update adds 178 boards and 29 shields.
If you are upgrading from 4.4, check the migration guide. The ring buffer claim/finish API is replaced by ring_buf_put_ptr() and ring_buf_get_ptr(), and CMake flash and debug targets are removed in favor of west. Henrik Brix Andersen and Tom Burdick served as release managers.