microPlatform update 0.19


Zephyr microPlatform changes for 0.19

Zephyr hits 1.12 feature freeze; this will not be the LTS, but carries many important new features.

Linux microPlatform changes for 0.19

No changes have gone into the LMP since 0.18.

Zephyr microPlatform


Zephyr hits 1.12 feature freeze; this will not be the LTS, but carries many important new features.


  • Zephyr 1.12 rc 1
  • No MCUboot changes
  • Minor application updates




  • Not addressed in this update


  • Not addressed in this update



  • OpenAMP (and its libmetal dependency) was merged to enable message-based cross-core communication. This carries BSD-3-Clause and BSD-2-Clause licenses.

A usage sample is in samples/subsys/openamp:


New Zephyr SDK:
  • Zephyr SDK version 0.9.3 has been released. Linux users should upgrade using the updated installation instructions:


Non-volatile Storage (NVS):
  • A long-running pull request to add a new storage mechanism for persistent data was merged. The new Non- Volatile Storage (NVS) subsystem is meant as an alternative to the existing FAT and NFFS file systems, as well as the Flash Circular Buffer (FCB) library which was ported to Zephyr from the MyNewt RTOS.

For more details, refer to the NVS subsystem documentation:


This would seem to pair well with the storage API changes discussed in the previous newsletter, which introduced greater abstraction over the storage backend.

k_call_stacks_analyze() deprecated:
  • The k_call_stacks_analyze() API was deprecated. Users are recommended to switch to using k_thread_foreach():


(Perhaps re-implementing or calling into a stack usage dumping routine for each thread.)

Userspace changes:
  • Numerous userspace-related features and optimizations were merged.

New API was merged for memory management from specified memory pools. The main functions are:

  • k_mem_pool_malloc(): http://docs.zephyrproject.org/api/kernel_api.html#_CPPv217k_mem_pool_mallocP10k_mem_pool6size_t
  • k_mem_pool_free(): http://docs.zephyrproject.org/api/kernel_api.html#_CPPv215k_mem_pool_freeP11k_mem_block

This is used to allow dynamic allocation of kernel objects from userspace.

Cleanup functions defined on a per-kernel-object-type basis can now be invoked when an object loses all permissions. This is used as a framework for automatic resource release for dynamically-allocated userspace objects.

New APIs were added for userspace allocation and freeing of kernel objects of various types:

  • k_pipe_alloc_init() and k_pipe_cleanup() for pipes: http://docs.zephyrproject.org/api/kernel_api.html#_CPPv217k_pipe_alloc_initP6k_pipe6size_t http://docs.zephyrproject.org/api/kernel_api.html#_CPPv214k_pipe_cleanupP6k_pipe
  • k_msgq_alloc_init() and k_msgq_cleanup() for message queues: http://docs.zephyrproject.org/api/kernel_api.html#_CPPv217k_msgq_alloc_initP6k_msgq6size_t5u32_t http://docs.zephyrproject.org/api/kernel_api.html#_CPPv214k_msgq_cleanupP6k_msgq
  • k_stack_alloc_init() and k_stack_cleanup() for stack objects: http://docs.zephyrproject.org/api/kernel_api.html#_CPPv218k_stack_alloc_initP7k_stackj http://docs.zephyrproject.org/api/kernel_api.html#_CPPv215k_stack_cleanupP7k_stack

Additional APIs for allowing userspace access to queues includes:

  • k_queue_alloc_append() and k_queue_alloc_prepend() http://docs.zephyrproject.org/api/kernel_api.html#_CPPv220k_queue_alloc_appendP7k_queuePv http://docs.zephyrproject.org/api/kernel_api.html#_CPPv221k_queue_alloc_prependP7k_queuePv
  • k_fifo_alloc_put(): http://docs.zephyrproject.org/api/kernel_api.html#c.k_fifo_alloc_put
  • k_lifo_alloc_put(): http://docs.zephyrproject.org/api/kernel_api.html#c.k_lifo_alloc_put

The k_poll Polling API is now also accessible from user mode:


An optimization was merged which avoids executing user/supervisor boundary checks when invoking system calls from privileged code in translation units defined under arch/.

Access to the k_object_access_revoke() routine from userspace was itself revoked, closing a hole where one thread could inappropriately revoke another's access to a kernel object. Userspace threads may revoke access to their own objects with k_object_release().

TCP TIME_WAIT config changes:
  • Configuration for how long the Zephyr TCP stack remains in the TIME_WAIT state during connection closure is now managed through the single CONFIG_NET_TCP_TIME_WAIT_DELAY option:


This replaces the previous CONFIG_NET_TCP_TIME_WAIT and CONFIG_NET_TCP_2MSL_TIME options. Applications using the old options will need updates.

  • Support for Arm's v8-M cores continues, with support for secure fault handling on Cortex-M23 along with other behind-the-scenes work on memory access privilege checks.

There is a new CONFIG_PLATFORM_SPECIFIC_INIT available on Arm targets. When enabled, the user must provide a _PlatformInit routine, which will be called at Zephyr startup before anything else happens.

Support was added to enable a Zephyr image running on an NXP LPC-based SoC to boot a slave Cortex M0+ core. (Board support was added for the slave core as lpcxpresso54114_m0.)

  • The Mesh shell now supports the recently-merged persistent storage mechanism.
Device Tree and Drivers:
  • Zephyr now supports the automobile Controller Area Network (CAN) protocol. The API is specified in include/can.h. The new API is userspace-aware. GPIO bindings were added for QMSI (Intel Quark) based devices, with nodes added for quark_se_c1000_ss.

Device tree bindings were added for real-time clocks (RTCs), as well as NXP Kinetis and QMSI based RTCs. SoC support was added for KW41Z and quark_se_c1000_ss.

Additional patches continuing the work migrating LED and buttons definitions to device tree were merged for mimxrt1050_evk and lpcxpresso54114. Device tree support for sensors on the argonkey board was also merged, along with em_starterkit device tree optimizations, and bindings for LSM6DSL sensors and Kinetis watchdogs.

A shim driver using the newly-stabilized watchdog API was added for NXP MCUx devices. SOC support is provided for K64 and KW2XD.

USBD (USB device) and USBFSOTG (USB full-speed On-the- Go) support was added for NXP Kinetis SoCs. USB support was also enabled for STMicro nucleo_f413zh.

WiFi support for the WINC1500 network controller was merged. This chip can be used to add networking via SPI. This is the first user of the new WiFi API which was merged during the v1.12 development cycle. Support can be enabled using CONFIG_WIFI_WINC1500. A driver was added for ILI9340 LCD displays.

External Libraries:
  • The OpenThread library version was bumped to db4759cc, to pull in some bug fixes.

The Atmel WINC1500 WiFi driver was merged as part of enabling WiFI on that chip. This is a BSD-3-Clause licensed HAL.

  • In a highly significant but (hopefully mostly) behind- the-scenes change, the scheduler was rewritten:


A new k_thread_foreach() API was merged, which allows iterating over threads:


This requires CONFIG_THREAD_MONITOR to be enabled. Creation and termination of existing threads is blocked via irq_lock() while the routine is executing.

  • The red-black tree implementation in include/misc/rb.h now has RB_FOR_EACH() and RB_FOR_EACH_CONTAINER() macros, for iterating over red-black tree nodes and the structs which contain them.

The POSIX compatibility layer has additional file system support APIs. Pulling in the POSIX headers defines macros which map POSIX names to Zephyr- specific file system APIs appropriately. This includes support for basic syscalls such as open(), read(), write(), close(), and friends, and also allows for directory operations such as rename(), stat(), and mkdir(). Refer to the headers in include/posix for more information.

There is also now support for the POSIX mutex APIs.

  • A new API was added for a singly-linked-list like type which allows storing two flags in each node, by relying on 4-byte pointer aligment. For details, refer to include/misc/sflist.h.
  • The LWM2M subsystem now includes support for marking resources as optional. Any resources so marked are not initialized by the core LWM2M subsystem; applications must initialize them using lwm2m_engine_set_res_data() and lwm2m_engine_get_res_data(). This enables remote administration of these resources by the LWM2M server through CREATE operations. It also enables future work where BOOTSTRAP operations will behave differently when encountering optional resources. As part of these changes, various object resources throughout the LWM2M core and in supported IPSO objects were marked optional appropriately.

The 802.15.4 subsystem now supports source address filtering and performing energy detection scans when OpenThread is in use.

  • New samples include:

  • a RPL border router application, samples/net/rpl_border_router: http://docs.zephyrproject.org/samples/net/rpl_border_router/README.html

  • A WiFi shell sample, samples/net/wifi: http://docs.zephyrproject.org/samples/net/wifi/README.html

  • An OpenAMP usage sample, samples/subsys/openamp: http://docs.zephyrproject.org/samples/subsys/ipc/openamp/README.html

  • An MCUX IPM mailbox example, samples/subsys/ipc/ipm_mcux: http://docs.zephyrproject.org/samples/subsys/ipc/ipm_mcux/README.html

  • A sample for the 96Boards ArgonKey, samples/boards/96b_argonkey: http://docs.zephyrproject.org/samples/boards/96b_argonkey/README.html

  • A CAN sample, samples/can, tested on stm32f072b_disco: http://docs.zephyrproject.org/samples/can/README.html

  • The flash, debug, and debugserver handlers now use a new meta-tool called "west". This is still a behind- the-scenes change; further work expected before the v1.12 release will add documentation for this tool.
  • The effort adding descriptions, cleanups, and other improvements to Zephyr's test cases to use them from a higher-level test management system continues.


  • Numerous drivers cleanups and bug fixes went in, affecting various devices.
  • Various Arm-specific fixes went in as part of the v8-M work.
  • A new CONFIG_BT_MESH_IVU_DIVIDER went in, which fixes an issue related to re-initializing initialization vectors. Various other Bluetooth cleanups and fixes went in, including removals of deprecated APIs and unused variables and documentation fixes.
  • Numerous fixes and additional Doxygen descriptions went into the test cases.
  • Networking fixes include net-app fixes for TLS warnings, source IPv4 address selection, build fixes with TCP disabled, and byte order handling; ethernet MAC address setting; LWM2M port handling fixes; dropping of invalid packets; and a couple of ICMPv6 fixes.
Build system:
  • Various build fixes, error handling and Kconfig dependency management improvements, k_call_stacks_analyze() removals, and more were added to the samples.

hawkBit and MQTT sample application


Minor Kconfig updates:
  • The application-specific Kconfig file was updated to follow along with upstream changes removing 'option env' symbols.


  • Not addressed in this update

LWM2M sample application


Minor Kconfig updates:
  • The application-specific Kconfig file was updated to follow along with upstream changes removing 'option env' symbols.
Optional values changes:
  • Minor changes were made following upstream API breaks which added optional resources to LWM2M objects.


  • Not addressed in this update

Linux microPlatform


No changes have gone into the LMP since 0.18.


  • No changes have gone into the LMP since 0.18.


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