Zephyr 4.5.0 (Working Draft)

We are pleased to announce the release of Zephyr version 4.5.0.

Major enhancements with this release include:

New driver classes

Zephyr 4.5 adds several new driver APIs, including:

• Clock Monitor for runtime observation of clock frequency

New subsystems

Zephyr 4.5 adds several new subsystem APIs, including:

• Video for controlling video drivers

An overview of the changes required or recommended when migrating your application from Zephyr v4.4.0 to Zephyr v4.5.0 can be found in the separate migration guide.

The following sections provide detailed lists of changes by component.

Security Vulnerability Related

The following CVEs are addressed by this release:

• CVE 2026-8718 Under embargo until 2026-08-08

• CVE 2026-9263 Under embargo until 2026-06-28

API Changes

Removed APIs and options

• Architectures

  • Xtensa

    • CONFIG_XTENSA_BACKTRACE_EXCEPTION_DUMP_HOOK

• Bluetooth

  • Host

    • The CONFIG_BT_RECV_CONTEXT choice and its options CONFIG_BT_RECV_WORKQ_SYS and CONFIG_BT_RECV_WORKQ_BT have been removed. The host now always processes low-priority HCI packets on the dedicated Bluetooth RX workqueue (the former CONFIG_BT_RECV_WORKQ_BT behavior). See the migration guide.

    • Selected Host work items have moved from the system workqueue to the dedicated Bluetooth RX workqueue. Application callbacks reached from those work items now run in the Bluetooth RX thread. See the migration guide for affected callback families.

    • The CONFIG_BT_HCI_RAW_H4 and CONFIG_BT_HCI_RAW_H4_ENABLE Kconfig options have been removed. They have had no effect since Zephyr 4.2, where the HCI raw layer switched to using H:4 packet encoding for all buffers unconditionally. Applications still setting these options can simply drop them.

• Counter

  • CONFIG_COUNTER_MAXIM_DS3231

• LLEXT

  • llext_get_fn_table, replaced by llext_get_fn_table_entry

• Networking

  • CONFIG_NET_TC_SKIP_FOR_HIGH_PRIO

  • CONFIG_NET_SOCKETS_POLL_MAX

  • CONFIG_NET_GPTP_CLOCK_ACCURACY_*

  • net_ipv6_set_hop_limit()

  • net_if_ipv4_get_netmask()

  • net_if_ipv4_set_netmask()

  • net_if_ipv4_set_netmask_by_index()

  • openthread_state_changed_cb_register()

  • openthread_state_changed_cb_unregister()

  • openthread_start()

  • openthread_api_mutex_lock()

  • openthread_api_mutex_try_lock()

  • openthread_api_mutex_unlock()

  • struct openthread_state_changed_cb

  • TLS_CREDENTIAL_SERVER_CERTIFICATE

  • start_11r_roaming

• Random

  • CONFIG_CTR_DRBG_CSPRNG_GENERATOR

  • CONFIG_CS_CTR_DRBG_PERSONALIZATION

• West sign support for imgtool, which was deprecated in Zephyr 4.0, has been removed.

Deprecated APIs and options

• Audio Codec

  • The audio_codec_api struct has been deprecated. Audio codec drivers are now expected to use the DEVICE_API macro to declare their driver API.

• Build system

  • The zephyr_file_copy() CMake function has been deprecated. Use the native file(COPY_FILE ...) CMake command instead.

• CPU Load

  • CONFIG_CPU_LOAD_METRIC and cpu_load_metric_get() are deprecated. The CPU load metric module has been merged into the unified CPU load module; use CONFIG_CPU_LOAD with the CONFIG_CPU_LOAD_BACKEND_RUNTIME_STATS backend and cpu_load_get_cpu().

• DMIC

  • The _dmic_ops struct has been deprecated. DMIC drivers are now expected to use the DEVICE_API macro to declare their driver API.

• Fuel Gauge

  • Deprecated various fuel gauge property enums and union fields in favor of new versions with explicit unit suffixes.

• LoRa

  • Renamed lora_recv_duty_cycle() to lora_recv_duty_cycle_async() to be consistent with the existing sync/async naming convention.

• Nordic

  • The internal SoC platform Kconfig symbols NRF_PLATFORM_HALTIUM and NRF_PLATFORM_LUMOS have been deprecated. Use specific SOC_SERIES_* Kconfig options instead.

  • The sysbuild Kconfig option SB_CONFIG_NRF_HALTIUM_GENERATE_UICR has been renamed to SB_CONFIG_NRF_GENERATE_UICR.

  • The Nordic SoC headers <haltium_power.h> and <haltium_pm_s2ram.h> have been renamed to <soc_power.h> and <soc_pm_s2ram.h> respectively.

• Ring buffer

  • The ring buffer item API (ring_buf_item_init(), ring_buf_item_put(), ring_buf_item_get(), ring_buf_item_space_get()) has been deprecated in favor of sys_ringq (see sys_ringq Data Structure).

• Networking

  • Deprecated LLMNR support (CONFIG_LLMNR_RESOLVER and CONFIG_LLMNR_RESPONDER). LLMNR is being phased out; use mDNS (CONFIG_MDNS_RESOLVER / CONFIG_MDNS_RESPONDER) instead.

• Networking Link layer

  • Deprecated CONFIG_NET_L2_PTP. Used CONFIG_NET_L2_PTP_TIMESTAMPING instead.

• Timer

  • New sys_clock_no_timeout() hook for handling of CONFIG_SYSTEM_CLOCK_SLOPPY_IDLE, replacing the call to sys_clock_set_timeout() with ticks=K_TICKS_FOREVER.

  • New sys_clock_idle_enter() hook for handling of entry in low-power state, replacing the call to sys_clock_set_timeout() with idle=true.

• Video

  • All functions in the video driver API (<zephyr/drivers/video.h>) have moved to the video subsystem (<zephyr/video/video.h>). Application only need to rename the #include.

• Work queue

  • k_work_q.thread has been deprecated. Use k_work_q.thread_id instead.

New APIs and options

• ADC

  • Optional adc_driver_api.ref_get callback and adc_ref_get() so applications and adc_raw_to_millivolts_dt() can use a driver-owned runtime millivolt scale for any adc_reference. Static adc_driver_api.ref_internal remains the fallback for ADC_REF_INTERNAL when the callback is NULL. adc_raw_to_millivolts_dt() falls back to channel DT zephyr,vref-mv when adc_ref_get() fails.

• Architectures

  • CONFIG_ARM_MPU_CM7_UNMAPPED_REGION (Arm Cortex-M7 catch-all MPU region for unmapped addresses, erratum 1013783 workaround)

  • CONFIG_EXCEPTION_DUMP (enabled by default, can be disabled to compile out the fault handler output on size constrained builds)

• Audio

  • pcm_stream_cfg.gain_db

  • audio_codec_eq_cfg

• Bluetooth

  • Audio

    • bt_ascs_register()

    • bt_ascs_unregister()

    • bt_bap_unicast_client_qos_from_group()

    • bt_bap_qos_cfg_eq()

  • Host

    • bt_conn_take()

    • bt_conn_drop()

    • bt_le_per_adv_update_did()

    • bt_le_adv_param.tx_power and BT_LE_ADV_OPT_TX_POWER to request a specific TX power level per extended advertising set.

    • bt_conn_cb.le_param_update_rejected

    • BT_HCI_QUIRK_NO_FLOW_CONTROL HCI device quirk for controllers that advertise but reject the controller to host flow control commands.

  • Mesh

    • bt_mesh_lpn_timing

    • bt_mesh_stat_lpn_timing_get()

    • bt_mesh_stat_lpn_timing_reset()

    • CONFIG_BT_MESH_LPN_OFFER_WAIT_TIMEOUT

• Crypto

  • CRYPTO_CIPHER_MODE_CFB

  • CRYPTO_CIPHER_MODE_OFB

  • cipher_cfb_op()

  • cipher_ofb_op()

• Devicetree

  • DT_IRQN_BY_NAME

  • DT_INST_IRQN_BY_NAME

• Haptics

  • haptics_monitor

  • haptics_monitor_type

  • haptics_source

  • haptics_config

  • haptics_calibrate()

  • haptics_monitor_get()

  • haptics_monitor_set()

  • haptics_select_source()

  • haptics_set_level()

  • haptics_stream_samples()

• HWSPINLOCK

  • HWSPINLOCK_SPINLOCK_ARRAY_DT_DEFINE

  • HWSPINLOCK_SPINLOCK_ARRAY_DT_INST_DEFINE

  • HWSPINLOCK_COMMON_CONFIG_FROM_DT_NODE

  • HWSPINLOCK_COMMON_CONFIG_FROM_DT_INST

• Kconfig

  • Add dt_partition_mtd preprocessor function (GitHub #111599)

• Kernel

  • k_thread_runtime_stats_is_enabled()

  • atomic_test_and_set_bit_to()

  • K_MSGQ_DEFINE_STATIC

  • K_MSGQ_DEFINE_TYPE

  • K_MSGQ_DEFINE_STATIC_TYPE

• LoRa

  • lora_recv_duty_cycle()

  • lora_recv_duty_cycle_async()

• Management

  • MCUmgr

    • Added support for SPI MCUmgr SMP transport, which can be enabled with CONFIG_MCUMGR_TRANSPORT_SPI.

• Network

  • Add net_eth_set_if_type_wifi() to set the ethernet interface type to Wi-Fi.

  • Add net_dhcpv4_set_reboot_hint() to seed the DHCPv4 client with a previously leased address for INIT-REBOOT.

  • Add an mDNS responder interface policy (CONFIG_MDNS_RESPONDER_IFACE_POLICY_ALLOWLIST, CONFIG_MDNS_RESPONDER_IFACE_POLICY_DENYLIST) together with CONFIG_MDNS_RESPONDER_IFACE_LIST to control on which network interfaces the mDNS responder operates.

  • Add mdns_responder_enable_iface() and mdns_responder_disable_iface() (CONFIG_MDNS_RESPONDER_RUNTIME_IFACE_CONTROL) to enable or disable the mDNS responder on a network interface at runtime.

  • Add a DHCPv6 server with IPv6 prefix delegation support (CONFIG_NET_DHCPV6_SERVER): net_dhcpv6_server_start(), net_dhcpv6_server_stop() and net_dhcpv6_server_foreach_lease().

  • Add IPv6 router role, that is, transmission of Router Advertisements (CONFIG_NET_IPV6_ND_RA_TX): net_if_ipv6_router_start(), net_if_ipv6_router_stop() and net_if_ipv6_prefix_set_advertise().

  • Add requesting router support to the DHCPv6 client, a delegated prefix can be sub-delegated onto downstream links via net_dhcpv6_params.downstream_ifaces.

  • Add net_eth_mcast_addr_add(), net_eth_mcast_addr_rm() and net_eth_mcast_addr_foreach(). The Ethernet L2 now keeps track of the link layer multicast addresses that an interface listens to, so an Ethernet driver is asked to change its receive filter only when a group is joined by its first user or left by its last one. Previously the IP level joins and the packet socket memberships were forwarded to the driver separately, and leaving one group could stop the device from listening to another group that needs the same link layer address. This happens easily as IPv4 multicast addresses map 32:1 to link layer addresses. A driver can also treat ETHERNET_CONFIG_TYPE_FILTER as a hint that the addresses changed and reprogram its filter by iterating them with net_eth_mcast_addr_foreach(), which suits devices that filter by a hash of the address. How many addresses an interface can track is the sum of what the enabled subsystems ask for, and CONFIG_NET_L2_ETHERNET_MCAST_FILTER_COUNT can raise it if an application needs more. A multicast destination address given to net_eth_mac_filter() or to NET_REQUEST_ETHERNET_SET_MAC_FILTER is counted the same way, so each such filter that an application sets must now also be unset by it, and unsetting one that was never set fails with -ENOENT.

  • Add ZSOCK_PACKET_ADD_MEMBERSHIP and ZSOCK_PACKET_DROP_MEMBERSHIP socket options at the ZSOCK_SOL_PACKET level (CONFIG_NET_SOCKETS_PACKET_MCAST_MEMBERSHIP), so that a packet socket can ask the network interface to start or stop listening to an extra L2 multicast address. On Ethernet the address is programmed to the receive filter of the device if it supports filtering, and a device that does not filter passes the group up anyway. A join that the interface cannot serve is reported to the application, ENOMEM if the interface cannot track another address and ENOTSUP if it is not an Ethernet interface. The membership changes are reported by the NET_EVENT_PACKET_MCAST_MEMBERSHIP_ADD and NET_EVENT_PACKET_MCAST_MEMBERSHIP_DROP network management events. Memberships still held when the socket is closed are dropped automatically, and CONFIG_NET_SOCKETS_PACKET_MCAST_MEMBERSHIP_COUNT sets how many memberships can be active at the same time.

• Power Management

  • LOG_DBG_PM_DEVICE_RUNTIME_GET

  • LOG_WRN_PM_DEVICE_RUNTIME_GET

  • LOG_ERR_PM_DEVICE_RUNTIME_GET

  • LOG_DBG_PM_DEVICE_RUNTIME_PUT

  • LOG_WRN_PM_DEVICE_RUNTIME_PUT

  • LOG_ERR_PM_DEVICE_RUNTIME_PUT

  • LOG_INST_DBG_PM_DEVICE_RUNTIME_GET

  • LOG_INST_WRN_PM_DEVICE_RUNTIME_GET

  • LOG_INST_ERR_PM_DEVICE_RUNTIME_GET

  • LOG_INST_DBG_PM_DEVICE_RUNTIME_PUT

  • LOG_INST_WRN_PM_DEVICE_RUNTIME_PUT

  • LOG_INST_ERR_PM_DEVICE_RUNTIME_PUT

• Ring buffer

  • sys_ringq (see sys_ringq Data Structure)

• Zbus

  • CONFIG_ZBUS_RUNTIME_CHANNEL_REGISTRATION

  • zbus_runtime_channel_init()

  • zbus_runtime_channel_register()

  • zbus_runtime_channel_unregister()

New Boards

• Arduino

  • Arduino Nesso N1 (arduino_nesso_n1)

• Seeed

  • Seeed Wio Tracker L1 (wio_tracker_l1)

• WCH

  • WCH CH32V103EVT (ch32v103evt)

New Shields

New Drivers

• ADC

  • Analog Devices AD4190-8 and AD4195-8 Sigma-Delta ADCs (adi,ad4190-8-adc, adi,ad4195-8-adc).

• GPIO

  • Diodes/Pericom PI4IOE5V6408 8-bit I2C-bus I/O expander (diodes,pi4ioe5v6408).

  • ST Zio connector for STM32 Nucleo-144 boards (st-zio-header).

• Input

  • VIRTIO input device (virtio,input).

• Sensors

  • Analog Devices ADXL313 3-axis accelerometer (adi,adxl313).

• Clock Monitor

  • nxp,cmu-fc — NXP Clock Monitoring Unit (Frequency Check) back-end for the new Clock Monitor subsystem.

  • nxp,cmu-fm — NXP Clock Monitoring Unit (Frequency Meter) back-end for the new Clock Monitor subsystem.

• USB

  • espressif,esp32-usb-otg-fs - Espressif USB-OTG full-speed controller with internal FS/LS PHY.

  • espressif,esp32-usb-otg-hs - Espressif USB-OTG high-speed controller with internal UTMI PHY.

New Samples

• MCTP I2C GPIO Top Node Sample (renamed from mctp_i2c_bus_owner)

• MCTP I3C Top Node Sample (renamed from mctp_i3c_bus_owner)

• samples/drivers/clock_monitor/check_freq — demonstrates WINDOW-mode out-of-window frequency checking on the new Clock Monitor.

• samples/drivers/clock_monitor/measure_freq — demonstrates MEASURE-mode one-shot frequency measurement on the new Clock Monitor.

Libraries / Subsystems

• Crypto

  • Added AES CFB and OFB cipher mode support.

• Mbed TLS

  • Mbed TLS was updated to version 4.1.1. Release notes can be found here.

  • TF-PSA-Crypto was updated to version 1.1.1. Release notes can be found here.

  • Added CONFIG_TF_PSA_CRYPTO_DISPATCH_DIR, which enables TF-PSA-Crypto to use custom implementations of crypto operation dispatch. This makes hardware acceleration of cryptographic operations possible by using an accelerator-aware dispatch implementation.

• TF-M

  • TF-M was updated from version 2.2.2 to version 2.3.0. Release notes can be found here.

  • TF-M can now be compiled using LLVM by setting ZEPHYR_TOOLCHAIN_VARIANT to zephyr/llvm.

• DFU

  • Added CONFIG_IMG_CUSTOM_SECTOR_SIZE to allow MCUboot to use a different sector size for reducing the swap-using-offset status area size.

• LoRa / LoRaWAN

  • Added a native LoRaWAN backend (CONFIG_LORA_MODULE_BACKEND_NATIVE) that implements LoRaWAN 1.0.x Class A directly on top of the LoRa radio driver, without the Semtech LoRaMac-node dependency. Currently supports the EU868 region.

  • lora_modem_config.sync_word

• Video

  • Introducing a video subsystem that inherits all the function names previously in video drivers.

• Zbus

  • CONFIG_ZBUS_MSG_SUBSCRIBER_NET_BUF_POOL_ISOLATION now works without requiring a dedicated pool on every channel (channels fall back to the shared pool until zbus_chan_set_msg_sub_pool() is called)

Devicetree

• Nodes can now use phandles to refer to their children without causing a cycle in the dependency graph and a build error. See dependency-mode how to use this new feature. (GitHub #108892)

  • DT_NODELABEL_C_TOKEN

  • DT_NODELABEL_C_TOKEN_BY_IDX

Other notable changes

• Build system

  • The minimum required CMake version has been raised to 3.28.0, a version satisfied by the CMake package in the Ubuntu 24.04 LTS package repositories. See the migration guide for options if your distribution ships an older version.

• Kernel

  • CONFIG_SCHED_CPU_MASK no longer depends on CONFIG_SCHED_SIMPLE. CPU affinity masks are now supported on all three scheduler backends: SCHED_SIMPLE (O(N) list scan), SCHED_SCALABLE (O(N) red/black tree walk), and SCHED_MULTIQ (O(P·N) per-priority bucket scan). See the updated SMP documentation for per-backend performance notes.

  • CONFIG_SCHED_CPU_MASK_PIN_ONLY now enforces the one-CPU-bit invariant at both the API boundary (cpu_mask_mod()) and at queue time (thread_runq()). Calling k_thread_cpu_mask_clear(), k_thread_cpu_mask_enable_all(), or k_thread_cpu_mask_disable() in PIN_ONLY mode triggers an assertion failure. Use k_thread_cpu_pin() to reassign a thread to a different CPU.

• Timer

  • With CONFIG_SYSTEM_CLOCK_SLOPPY_IDLE enabled, a driver may no longer stop its time base as soon as no timeout is pending, if that breaks sys_clock_cycle_get_32() / sys_clock_cycle_get_64(). Those must keep counting while the CPU runs. Stopping the time base is permitted only from sys_clock_idle_enter(), where sys_clock_idle_exit() is guaranteed to follow.

  • Tickless system-timer drivers can now be built on a shared implementation header, drivers/timer/system_timer_generic.h, which owns the tick accounting each driver previously open-coded: the cycle-to-tick conversion, the announce baseline, the tick-aligned deadline and the counter wrap and range handling. A driver reduces to a few cycle-domain primitives, a cycle-counter read plus an absolute-compare arm. See the migration guide for how to use it (GitHub #115844).

• Wi-Fi

  • Removed the samples/net/wifi/test_certs/rsa2k enterprise test certificates (DES-encrypted private keys). Use rsa2k_no_des instead.

  • The transmit power ceiling properties in wifi-tx-power-2g.yaml and wifi-tx-power-5g.yaml are no longer required and now carry conservative defaults, so a board that has not been characterised errs on the side of transmitting too little rather than exceeding a regulatory limit. Boards that have measured their own limits continue to state them explicitly, so no board changes behaviour.

• MCUboot

  • SB_CONFIG_BOOT_SIGNATURE_KEY_FILE now accepts a comma-separated list of key files, embedding the public half of each in the MCUboot bootloader. When more than one key is given, MCUboot accepts an image signed with any of them – the typical use is a development bootloader that boots both development- and production-signed images, while production bootloaders embed only the production key. The first entry is the key the application is signed with and the rest are verification-only public keys. See Signing Binaries.

• NXP

  • The NXP LPC DTSI files have been reorganized from the flat dts/arm/nxp/lpc/ directory into per-series subdirectories (lpc11u6x/, lpc51u68/, lpc54xxx/, lpc55xxx/, lpc84x/). See the migration guide for how to update out-of-tree board includes.

  • The NXP Kinetis DTSI files have been reorganized from the flat dts/arm/nxp/kinetis/ directory into per-series subdirectories (k2x/, k32lx/, k6x/, k8x/, ke1xf/, ke1xz/, kl2x/, kv5x/, kwx/). See the migration guide for how to update out-of-tree board includes.

  • The NXP MCX DTSI files have been reorganized from the flat dts/arm/nxp/mcx/ directory into per-series subdirectories (mcxa/, mcxc/, mcxe/, mcxl/, mcxn/, mcxw/). See the migration guide for how to update out-of-tree board includes.

  • The NXP i.MX RT DTSI files have been reorganized from the flat dts/arm/nxp/imxrt/ directory into per-series subdirectories (imxrt10xx/, imxrt11xx/, imxrt5xx/, imxrt6xx/, imxrt7xx/, imxrt118x/). See the migration guide for how to update out-of-tree board includes.

• Arm

  • The non-secure variant of

    Arm Musca-S1 (v2m_musca_s1/musca_s1/ns) has been removed due to TF-M removing platform support for this board.

  • As a consequence of the above, the secure variant of Arm Musca-S1 (v2m_musca_s1) has been deprecated. This is to avoid a confusing state of partial support.

Trusted Firmware-A

• CONFIG_TFA_BUILD_FIP is introduced to configure FIP (Firmware Image Package) generation. FIP generation is by default disabled, but can be enabled by setting CONFIG_TFA_BUILD_FIP=y in prj.conf or for custom boards, in the board’s <board>_defconfig file.