Zephyr 4.4.0 (Working Draft)

We are pleased to announce the release of Zephyr version 4.4.0.

Major enhancements with this release include:

An overview of the changes required or recommended when migrating your application from Zephyr v4.3.0 to Zephyr v4.4.0 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 2025-53022 (TF-M) FWU does not check the length of the TLV’s payload

API Changes

• Architectures

  • Xtensa

    • Removed as these are architectural features:

      • CONFIG_XTENSA_MMU_DOUBLE_MAP

      • CONFIG_XTENSA_RPO_CACHE

      • CONFIG_XTENSA_CACHED_REGION

      • CONFIG_XTENSA_UNCACHED_REGION

Removed APIs and options

Deprecated APIs and options

• Bluetooth

  • Mesh

    • The function bt_mesh_input_number() was deprecated. Applications should use bt_mesh_input_numeric() instead.

    • The callback output_number in bt_mesh_prov structure was deprecated. Applications should use output_numeric callback instead.

    • The CONFIG_BT_MESH_MODEL_VND_MSG_CID_FORCE option has been deprecated.

  • Host

    • bt_conn_le_info.interval has been deprecated. Use bt_conn_le_info.interval_us instead. Note that the units have changed: interval was in units of 1.25 milliseconds, while interval_us is in microseconds.

• POSIX

  • CONFIG_XOPEN_STREAMS was deprecated. Instead, use CONFIG_XSI_STREAMS

• Sensors

  • NXP

    • Deprecated the mcux_lpcmp driver (drivers/sensor/nxp/mcux_lpcmp/mcux_lpcmp.c). It is currently scheduled to be removed in Zephyr 4.6, along with the mcux_lpcmp sample. (GitHub #100998).

New APIs and options

• ADC

  • ADC_DT_SPEC_GET_BY_IDX_OR

  • ADC_DT_SPEC_GET_BY_NAME_OR

  • ADC_DT_SPEC_GET_OR

  • ADC_DT_SPEC_INST_GET_BY_IDX_OR

  • ADC_DT_SPEC_INST_GET_BY_NAME_OR

  • ADC_DT_SPEC_INST_GET_OR

• Architectures

  • Xtensa

    • CONFIG_XTENSA_MMU_USE_DEFAULT_MAPPINGS

• Audio

  • PDM_DT_IO_CFG_GET

  • PDM_DT_HAS_LEFT_CHANNEL

  • PDM_DT_HAS_RIGHT_CHANNEL

• Bluetooth

  • Audio

    • bt_bap_ep_get_conn()

  • Host

    • bt_gatt_cb_unregister() Added an API to unregister GATT callback handlers.

    • bt_le_per_adv_sync_cb_unregister()

  • Mesh

    • bt_mesh_input_numeric() to provide provisioning numeric input OOB value.

    • output_numeric callback in bt_mesh_prov structure to output numeric values during provisioning.

    • CONFIG_BT_MESH_CDB_KEY_SYNC to enable key synchronization between the Configuration Database (CDB) and the local Subnet and AppKey storages when keys are added, deleted, or updated during key refresh procedure. The option is enabled by default.

  • Services

    • Introduced Alert Notification Service (ANS) CONFIG_BT_ANS

• Build system

  • Added slot1-partition snippet.

  • Sysbuild

    • Added SB_CONFIG_MERGED_HEX_FILES which allows generating merged hex files.

    • Added experimental ExternalZephyrVariantProject_Add() sysbuild CMake function which allows for adding variant images to projects which are based on existing images in a build.

    • Added SB_CONFIG_MCUBOOT_DIRECT_XIP_GENERATE_VARIANT which allows for generating slot 1 images automatically in sysbuild projects when using MCUboot in direct-xip mode.

• Display

  • SSD1325_DEFAULT_CONTRAST

  • SSD1325_CONV_BUFFER_LINES

• Ethernet

  • Driver MAC address configuration with support for NVMEM cell.

    • net_eth_mac_load()

    • net_eth_mac_config

    • NET_ETH_MAC_DT_CONFIG_INIT and NET_ETH_MAC_DT_INST_CONFIG_INIT

  • Added ethernet_stats_type and optional get_stats_type callback in ethernet_api to allow filtering of ethernet statistics by type (common, vendor, or all). Drivers that support vendor-specific statistics can implement get_stats_type to skip expensive FW queries when only common stats are requested. The existing get_stats API remains unchanged for backward compatibility.

• Flash

  • jedec,mspi-nor now allows MSPI configuration of read, write and control commands separately via devicetree.

• IPM

  • IPM callbacks for the mailbox backend now correctly handle signal-only mailbox mailbox usage. Applications should be prepared to receive a NULL payload pointer in IPM callbacks when no data buffer is provided by the mailbox.

• Modem

  • CONFIG_MODEM_HL78XX_AT_SHELL

  • CONFIG_MODEM_HL78XX_AIRVANTAGE

• NVMEM

  • Flash device support

    • CONFIG_NVMEM_FLASH

    • CONFIG_NVMEM_FLASH_WRITE

• Networking

  • Wi-Fi

    • Add support for Wi-Fi Direct (P2P) mode.

• PWM

  • Extended API with PWM events

    • pwm_event_callback to hold a pwm event callback

    • pwm_init_event_callback() to help initialize a pwm_event_callback object

    • pwm_add_event_callback() to add a callback

    • pwm_remove_event_callback() to remove a callback

    • manage_event_callback in pwm_driver_api to manage pwm events

    • CONFIG_PWM_EVENT

• Power

  • The new voltage-scale property of st,stm32u5-pwr can be used to select the voltage scale manually on STM32U5 series via Devicetree. This notably enables usage of the USB controller at lower system clock frequencies.

• Settings

  • CONFIG_SETTINGS_SAVE_SINGLE_SUBTREE_WITHOUT_MODIFICATION

  • CONFIG_SETTINGS_SAVE_SINGLE_SUBTREE_WITHOUT_MODIFICATION_VALUE_SIZE

• Sys

  • COND_CASE_1

• Timeutil

  • CONFIG_TIMEUTIL_APPLY_SKEW

• Utilities

  • COBS streaming support

    • cobs_decoder

    • cobs_decoder_init()

    • cobs_decoder_write()

    • cobs_decoder_close()

    • cobs_encoder

    • cobs_encoder_init()

    • cobs_encoder_write()

    • cobs_encoder_close()

• Video

  • CONFIG_VIDEO_BUFFER_POOL_HEAP_SIZE

  • CONFIG_VIDEO_BUFFER_POOL_ZEPHYR_REGION

  • CONFIG_VIDEO_BUFFER_POOL_ZEPHYR_REGION_NAME

New Boards

• Ai-Thinker Co., Ltd.

  • Ai-Thinker M61-32S development board (ai_m61_32s_kit)

  • Rename ai_m62_12f and ai_wb2_12f to ai_m62_12f_kit and ai_wb2_12f_kit

New Shields

New Drivers

• Comparator

  • Added NXP low power comparator driver (nxp,lpcmp). (GitHub #100998)

• Radio

  • radio-fem-two-ctrl-pins (renamed from generic-fem-two-ctrl-pins)

  • radio-gpio-coex (renamed from gpio-radio-coex)

• Display

  • solomon,ssd1325

New Samples

• Peripheral ANS

DeviceTree

• DT_CHILD_BY_UNIT_ADDR_INT

• DT_INST_CHILD_BY_UNIT_ADDR_INT

Libraries / Subsystems

• LoRa/LoRaWAN

  • lora_airtime()

• Mbed TLS

  • Added CONFIG_MBEDTLS_VERSION_C to simplify the export of version information from Mbed TLS. If enabled, the mbedtls_version_get_number() function will be available.

Other notable changes

• TF-M was updated to version 2.2.2 (from 2.2.0). The release notes can be found at:

  • https://trustedfirmware-m.readthedocs.io/en/tf-mv2.2.2/releases/2.2.1.html

  • https://trustedfirmware-m.readthedocs.io/en/tf-mv2.2.2/releases/2.2.2.html