Release-2021.10

RIOT-2021.10 - Release Notes

RIOT is a multi-threading operating system which enables soft real-time capabilities and comes with support for a range of devices that are typically found in the Internet of Things: 8-bit and 16-bit microcontrollers as well as light-weight 32-bit processors.

RIOT is based on the following design principles: energy-efficiency, softreal-time capabilities, small memory footprint, modularity, and uniform API access, independent of the underlying hardware (with partial POSIX compliance).

RIOT is developed by an international open-source community which is independent of specific vendors (e.g. similarly to the Linux community) and is licensed with a non-viral copyleft license (LGPLv2.1), which allows indirect business models around the free open-source software platform provided by RIOT.

About this release

The 2021.10 release includes:

The last three months again brought many new features, fixes and improvements to the RIOT codebase.
There is new hardware support, new helper functions and many new modules that help with building IoT applications.

Some of the new features are:

GCOAP DTLS (#15549)

The GCOAP CoAP library now supports transport encryption via tinyDTLS.
This is a compile-time toggle, so either all requests are encrypted or none.
There is already a PR (#16688) that will allow to mix encrypted and unencrypted requests.

FIDO2 support (#16489)

We now have an implementation of the Fast Identity Online 2 (FIDO2) specification.
With this you can use any RIOT device with USB support as an authentication token similar to the YubiKey.

RPL-over-BLE (#16364)

The 6LoWPAN over Bluetooth Low Energy module has gained support for the RPL routing protocol.
With this it's now possible to set up IPv6 based mesh networks over BLE on chips supported by the Nimble Bluetooth stack.

GNRC TCP (#16494)

RIOT's native GNRC network stack now has support for the TCP protocol via the socket API.
Now you can switch between LWIP and GNRC without changing your application.

DHCPv6 relay agent (#16606)

The DHCP module can now act as a relay, forwarding DHCPv6 requests for multihop-operation.

DHCPv6 IA_NA support (#16228)

The DHCPv6 client can now also request non-temporary addresses as an alternative to Stateless Access Autoconfiguration (SLAAC) that is used by default.
The feature can be enabled by selecting the dhcpv6_client_ia_na module.

gnrc_ipv6_auto_subnets (#16536, #16750)

This new module allows to split a large IPv6 prefix into smaller ones that can be used to configure downstream interfaces with a prefix.
The process can be repeated recursively for a cascading subnet topology.

This can be a lightweight alternative to DHCPv6 that only relies on router advertisements.

For more details on this, see the talk at the 2021 RIOT summit.

UDP benchmark (#16710)

The examples section has gained a UDP benchmark.
This can be used as a network stress test and is accompanied by a host tool (dist/tools/benchmark_udp) that acts as the benchmark server to which the benchmark clients will connect.

URI template processor (#16702)

URI templates up to level 3 (according to RFC 6570) can now be parsed with this tool.

riotboot serial flasher (#15493)

RIOT's native bootloader has gained the ability to load a firmware via UART.
This allows to program a board without the need for external programmers, a serial console is enough.

RTC mem for sam0 and STM32 (#16758)

Many real-time clocks have the ability to store a few bytes in their memory as user data. This memory is retained across reboots and deep sleep.

We now have an interface for this feature and implemented it on SAM L21, SAM D5x/E5x and STM32.

LWIP improvements (#16162, #16761, #16636, #16762)

The alternative LWIP network stack can now make use of multiple interfaces.
Initialisation is done using the new XFA (cross-file array) feature so new drivers can be added by only adding a single file.

Advanced topologies in ZEP dispatcher (#15773)

With socket_zep and the ZEP dispatcher it is possible to simulate a virtual IEEE 802.15.4 network with native nodes.
ZEP dispatcher has now gained support for lossy connections that make this simulation behave closer to reality.

There are also PRs pending to automatically generate such topologies (#16889)
and to hook up the ZEP dispatcher to the foren6 network visualizer (#16879).

RIOT_VERSION_CODE macro (#16765)

We have added a RIOT_VERSION_CODE macro that can be used by external modules / boards to check against which RIOT version it is compiled.

This allows to react to API changes if the module is built against different versions of RIOT.

gnrc_netif_ipv6_wait_for_global_address() (#16824)

For apps that want to connect to a remote server, send some data and then go back to sleep, there is now the new gnrc_netif_ipv6_wait_for_global_address() function.

This function blocks until a global address has been configured (e.g. via router advertisement) or a timeout happens.
So no more guessing if a connection can yet be established or if the interface is not configured yet.

This feature depends on the gnrc_netif_bus module.

netutils_get_ipv6() (#16634)

This simple function can parse a IPv6 address from a string.
But that's not all - if the sock_dns module is enabled, the string can also be a hostname which will then be resolved.

This provides a small and simple alternative to getaddrinfo() that can be used by shell commands and applications alike.

gnrc_icmpv6_echo corruption detection (#15622)

On Linux the ping command from iputils has the neat feature that it fills the payload with of the ICMP echo request with a pattern that is then echoed back by the receiver.

That means it can detect if the payload got corrupted on the way, e.g. by broken fragmentation or other errors.

The RIOT ping command now also implements this feature that lets you easily detect if something broke along the way.

New Hardware Support

In this cycle we have seen the addition of three new MCU families!
Our latest additions are the Raspberry Pi RP2040 (#16609) and the GD32VF103 RISC-V MCU from GigaDevice (#16036).

Both only have very basic support so far (only GPIO, UART and timers), which still leaves many low hanging fruits for adding peripheral drivers. (#15822, #16935)
Patches welcome!

The nRF9160 is closer to it's nRF52 siblings (#16650), but brings GPS and LTE-M/NB-IoT peripherals. While we are not there yet, there is ongoing work to also support these in RIOT.

The ATxmega family of 8-bit MCUs can now make use of the EBI interface to use external memory. (#16288) The new XMEGA-A1 Xplained already makes use of this feature. (#15758)

On the STM32 side we have now support for the nucleo-wl55jc and it's LoRa transceiver.
The IEEE 802.15.4 / BLE radio on the STM32WB family is however still waiting for a driver.

The common LM75 family of temperature drivers is now supported by RIOT. (#16678)

The Ethernet driver for the SAM E5x line of MCUs is now stable. (#16683)

The sub-MAC layer that implements common MAC features for IEEE 802.15.4 radios has again seen many improvements.
It is currently used by the nRF52 and CC2538 line of MCUs.

API changes

The spi_acquire() no longer returns an error code but will throw an assertion
if called with the wrong parameters.
This allows to speed up SPI operations a bit as SPI parameters are usually fixed
at compile time.

The gnrc_netdev_default was replaced by the network stack agnostic
netdev_default module.

For now gnrc_netdev_default remains an alias for netdev_default, but it will
be removed in a future release.

Summary

263 pull requests, composed of 590 commits, have been merged since the
last release, and 14 issues have been solved. 36 people contributed with
code in 98 days. 1756 files have been touched with 138909 (+) insertions and
12027 deletions (-).

Notations used below

+ means new feature/item
* means modified feature/item
- means removed feature/item

New features and changes

Core (3)

• core/sched: add runq_callback hook and runq inspection functions (#16463)
• core: add irq_is_enabled() function to irq interface (#11117)

• core/msg doc: Clarify; elaborating on interaction with queue (#16794)

System Libraries (12)

• riotboot: implement serial flasher (#15493)
• FIDO2 support in RIOT (#16489)
• test_utils: add UDP benchmark (#16710)
• uri_parser: provide function to split query (#16695)
• usbus/hid_io: add missing header file, add RX callback function (#16689)
• ut_process: initial import of a URI template processor (#16702)

• sys/picolibc_syscalls_default: support new picolibc stdio globals
  [backport 2021.10] (#17020)
• sys/random/fortuna: change interval ressed to ms (#16594)
• sys/shell/commands/gnrc_icmpv6_echo: test for ICMPv6 reply corruption (#15622)
• sys/shell/commands: gnrc_icmpv6_echo: use msg_avail() (#16611)
• uri_parser: constify result (#16707)

• sys/credman: add key load functions (#16263)

Networking (49)

• dhcpv6_relay: initial import of a lightweight DHCPv6 relay agent (#16606)
• gnrc/netif: add gnrc_netif_ipv6_wait_for_global_address() (#16824)
• gnrc_ipv6_nib: handle route information option and add config to add
  to final RAs (#16568)
• gnrc_ipv6_simple_subnets: auto-configuration for nested subnets on a
  simple tree topology (#16536)
• gnrc_netif: add gnrc_netif_ipv6_add_prefix() & helper functions (#16672)
• gnrc_sock_tcp: add gnrc sock tcp (#16494)
• gnrc_tcp: Add GNRC_TCP_NO_TIMEOUT (#16735)
• net/BLE: add support for RPL-over-BLE (#16364)
• net/gcoap: support DTLS (#15549)
• net/gnrc_lorawan: implement unconfirmed uplink redundancy (#15946)
• net/netif: add function to get interface by name from a buffer (#16709)
• netutils: add netutils_get_ipv6() (#16634)
• sys/net/dhcpv6: Add IA_NA support to the DHCPv6 client (#16228)
• tests/gnrc_lorawan: add initial tests (#16654)

• dhcpv6_client: make IA_PD an optional module (#16658)
• dhcpv6_client: mrd calculation fixed (#16679)
• dhcpv6_client: refactor to use event_timeout for non-sock timeouts (#16668)
• drivers/sx126x : r/NETOPT_RX_TIMEOUT/NETOPT_RX_SYMBOL_TIMEOUT (#16599)
• gnrc/ipv6_auto_subnets: relax topology requirements (#16750)
• gnrc/nib: consolidate prefix removal code in
  _nib_offl_remove_prefix() (#16729)
• gnrc_ipv6_nib: provide functions to get offset of public timestamps (#16706)
• gnrc_netif_pktq: schedule immediately if timer us is equal to zero (#16745)
• gnrc_tcp: align with sock tcp (#16493)
• gnrc_tcp: experimental feature "dynamic msl" (#16764)
• gnrc_tcp: handle zero size buffers (#16738)
• ipv6: fix typo in ipv6_addr_to_str documentation (#16828)
• netdev/lora: fix size of NETOPT_RX_SYMBOL_TIMEOUT (#16604)
• sock_dns: factor out message parsing and composition (#16669)
• sys/net/dhcpv6: Refactor DHCPv6 client (#16728)
• sys/net/dhcpv6: Refactor IA_NA implementation (#16724)
• sys/net/netopt: Drop deprecated NETOPT_MAX_PACKET_SIZE (#16023)
• tree-wide: avoid explicit cast to netdev (#16577)

Packages (8)

• pkg/wakaama: add get set functions and cleanup client connection (#16203)

• make: support package mirrors [backport 2021.10] (#16996)
• pkg/edhoc-c: ignore llvm flagged error (#16871)
• pkg/edhoc-c: remove nimble blacklist (#16819)
• pkg/edhoc: bump version (#16708)
• pkg/nanocbor: bump version (#16829)
• pkg/tinydtls: bump version (#16624)
• pkg/nimble/autoadv: make AD flag optional (#16703)
• pkg/nimble: bump version, rmv patches (#16830)
• pkg/nimble: configure BLE_LL_INIT_SLOT_SIZE to 1 (#16602)
• pkg/nimble: have RIOT always initialize nimble timers (#16623)
• pkg/nimble: use tinycrypt pkg (#16540)

• pkg/lwip: add auto-init for DOSE & at86rf215, cc2538_rf (#16761)
• pkg/lwip: Add thread safety check when using DEVELHELP (#16259)
• pkg/nimble/netif: add nimble_netif_accept_direct() (#16603)
• pkg/nimble/scanner: add function to set scan duration (#16701)

• pkg/lwip: Allow initializing different types of netifs (#16162)
• pkg/lwip: implement netif_get_name() (#16741)
• pkg/semtech-loramac: forward uplink schedule request to upper layer (#16961)
• pkg/tinydtls: handling of close_notify (#16422)

Boards (19)

• boards/{pic32-wifire,6lowpan-clicker}: Add CLOCK_CORECLOCK (#16607)
• boards: Introduce atxmega-a1-xplained board (#16289)
• gd32v/seeedstudio-gd32: Initial support (#16036)

• boards/adafruit-clue: fix doxygen warnings (#16847)
• boards/lora-e5-dev: initial support (#16660)
• boards/nrf52: replace gnrc_netdev_default with netdev_default (#16788)
• boards/saml21-xpro: configure UART & SPI on EXT2, 3 (#16694)

CPU (27)

• cpu/atxmega/periph: Add ebi driver (#16288)

• cpu/atxmega: Fix features config (#16742)

• cpu/nrf9160: add initial support for nRF9160DK board (#16650)
• cpu/nrf9160: add twi and spi support (#16814)
• cpu/rpx0xx: add periph timer (#16627)
• cpu/rpx0xx: port RIOT to the Raspberry Pi RP2040 MCU (#16609)
• cpu/stm32: added ADC for g0 (#16885)
• cpu/stm32: added APB12 bus multiplier entry for applicable cpus (#16881)
• cpu/nrf52: i2c: add support for 16-bit register addresses (#16711)
• cpu/riscv: add CPU_ARCH information (#16877)
• cpu/stm32: add rtc_mem (#16802)
• cpu/stm32: added RAM_LEN identifier for stm32g03x (#16886)
• stm32/spi : Add check for GPIO_UNDEF (#16625)
• cpu/nrf52: add SAUL driver for VDDH sensor (#16003)

• avr_libc_extra: implement strerror() (#16717)
• cpu/cc2538: don't pollute global namespace with cc2538_rfcore.h (#16863)
• cpu/kinetis: fix RAM_LEN calculation (#16608)
• cpu/native: fix thread_yield_higher() with IRQs disabled (#16754)
• cpu/native: make use of stdio_read() / stdio_write() (#16822)
• cpu/rpx0xx: fix minor gpio warnings (#16685)
• cpu/sam0: improve ethernet driver resilience (#16683)
• cpu/stm32/periph/rtc_all.c for CPU_FAM_STM32L5 support. (#16656)
• riscv: Simplify reset trampoline (#16876)

Device Drivers (7)

• drivers/cc2538_rf: remove cc2538_rf_netdev_legacy (#16628)
• drivers/nrf802154: remove nrf802154_rf_netdev_legacy (#16630)
• drivers/sx127x: remove ZTIMER_USEC dependency (#15030)
• ieee802154/radio_hal: detach hal descriptor from driver (#16534)
• ieee802154/submac: reimplement using FSM (#16746)
• ieee802154/submac: avoid race condition between RX_DONE and
  ACK_TIMEOUT (#16964)
• ieee802154/submac: fix leftovers of #16746 (#16823)

• drivers/dose: make use of start condition received interrupt (#16506)
• drivers/periph: define rtc_mem and implement it for sam0_common (#16758)
• drivers/cc110x: add power off (sleep) functions (#16232)
• drivers/lm75: add SAUL integration (#16763)
• drivers/lpsxxx: add support for lps22hh (#16880)
• rtt_rtc: add rtt_rtc_settimeofday() & rtt_rtc_gettimeofday() (#16682)

• drivers/at86rf215: remove msg queue dependency (#16747)
• drivers/lm75: driver for the lm75 sensor and derivatives (#16678)

• sx126x: add support for multiple simultaneous variants (#16597)
• drivers/ili9341: add rotation mode to ili9341_params_t (#16773)
• drivers/sx126x: Add support for Nucleo -WL55JC (#16579)

• drivers/cc110x: use pseudo-modules for band selection (#16865)

Documentation (9)

• boards/nrf52840dongle docs: Introduce "quick start" section (#15658)
• dist/tools/doccheck: add exclude file for warnings and use it (#16779)

• cpu: fix doxygen grouping warnings (#16813)
• doc/doxygen/src/advanced-build-system-tricks: fix no udev link (#16810)
• doc/doxygen: increase dot graph max nodes (#16686)
• doc/porting-boards.md: improve with porting graph and reference
  section (#15981)
• feather-nrf52840: several fixes to documentation (#16777)
• net/ieee802154_security doc: Shape security expectations (#16841)
• README.md: fix doc link (#16786)

Build System / Tooling (8)

• build system: add machine-readable RIOT_VERSION_CODE macro (#16765)
• build system: add VERBOSE_ASSERT flag (#16884)
• make: add capability to check config for test-with-config (#16795)
• makefiles/clang-tidy: initial support (#16509)

• dist/tools/compile_and_test_for_board: fix W1514 (#16772)
• dist/tools/doccheck: generate exclude_patterns using C.UTF-8 (#16846)
• dist/tools/pyterm: ipv6 address support for tcp_serial option (#16726)
• dist/tools: use f-strings where possible (#16867)
• Makefile.include: only warn if not curl, wget, unzip, 7z (#16784)

• tools/zep_dispatch: add support for advanced topologies (#15773)

• Remove which from shell invocations (#16776)

Kconfig (5)

• cpu/cc2538: Add Kconfig support (#16719)
• makefiles/kconfig.mk: generate config file from RIOT_CONFIG_%
  environment variables (#16052)

• drivers/lm75: fixed a typo in Kconfig (#16825)
• drivers/mtd: fix Kconfig dependencies (#16836)
• makefiles/kconfig.mk: force SHOULD_USE_KCONFIG if config file is
  present (#16641)

Examples (3)

• examples/lorawan: add LoRaWAN keys to DOCKER_ENV_VARS (#17010)

• examples/nimble_*: use nimble_autoadv module (#13506)

• examples/suit_update: Add compatibility with native (#15994)

Testing (10)

• dist/pythonlibs/riotctrl_shell/tests/common: add expect to mock (#17003)
• gnrc_tcp: refactor tests (#16461)
• tests/gnrc_dhcpv6_client: add script to check if $IFACE exists (#16797)

• CODEOWNERS: remove Robert Hartung (#16858)
• gh/workflows/release-tests: update LoRaWAN parameters to ttnv3
  [backport 2021.10] (#17013)
• Small fatfs usability fixes (#16800)
• tests/gnrc_dhcpv6_client: kill potential previous Kea session (#16820)
• tests/ieee802154_hal: check error codes and improve error reporting (#16556)
• tests/unittests/tests-ipv6_hdr: fix too short ipv6_hdr_t allocations (#16616)
• tests/ieee802154_submac: remove netdev dependency (#16826)

API Changes (5)

• drivers/ina3221: style fixes and improvements (#15915)
• drivers/periph_spi: let spi_acquire return void (#15902)
• gnrc_tcp: rewrite passive open (#16459)
• nanocoap & gcoap: allow path to be non-\0-terminated. (#16712)
• sys/net/nanocoap: block_finish returns if more are expected (#16704)

Uncategorized (3)

• README.md: add graphical logo (#16856)
• release-notes.txt: add 2021.07 release notes (#16651)

• README.md: Expose HiL CI overview link (#16720)
• Remove duplicated includes introduced in #15902 (#16798)
• treewide: Fix "too many consecutive empty lines" warnings (#16733)

And 63 minor changes.

Deprecations

Deprecations (1)

• gnrc: deprecate gnrc_netdev_default, use netdev_default instead (#16744)

Bug fixes (32)

• boards/nucleo-wl55jc: add SX126X_PARAM_TYPE to board.h (#16646)
• build system: add fallback for RIOT_VERSION_CODE (#16895)
• cpu/avr8_common: Fix link with binutils > 2.35.2 (#16790)
• cpu/cortexm: ldscripts: bkup-ram -> bkup_ram (#16753)
• cpu/esp_common: fix boot issue on ESP8266 (#16639)
• cpu/saml21: uart: use arithmetic baud rate mode (#16693)
• dhcpv6_client: keep integers in retransmission calculations signed
  [backport 2021.10] (#16995)
• drivers/cc2538_rf: fix deadlock when receiving too fast. (#16716)
• drivers/sx126x: fix netdev send and recv function (#16570)
• event_timeout: check clock before removing ztimer on clear (#16667)
• gnrc/nib: gnrc_ipv6_nib_get_next_hop_l2addr(): only assume neighbor
  cache entries to always be on-link (#16671)
• gnrc/sock: recv avoid spinning xtimer (#16831)
• gnrc_ipv6_nib: consider largest prefix match when deciding if host
  on-link (#16557)
• gnrc_ipv6_nib: queue packets that trigger probing on border router
  [backport 2021.10] (#16949)
• gnrc_lorawan: fix gnrc_pktbuf_release_error (introduced by #16080) (#16617)
• gnrc_sock: imply end-point netif only if unset (#16643)
• ieee802154/submac: fix initialization code (#16533)
• Makefile.base: cleanup non selected source object files [backport
  2021.10] (#16953)
• mtd: fix mtd_write_page() across sector boundaries (#16848)
• net/gnrc_lorawan: fix pick channel (#16664)
• net/lorawan: Revert #16604 and fix NETOPT_RX_SYMBOL_TIMEOUT
  documentation (#16640)
• netutils: get interface by name rather than ID (#16673)
• pkg/lwip: Fix compilation without IPv6 (#16762)
• pkg/lwip: Fix DHCP autostart (#16636)
• pkg/mynewt-core: initial commit (#16348)
• pkg/nimble/autoconn: stop scan/adv on NETIF_ABORT_SLAVE (#16699)
• pkg/wakaama: fix object common get functions (#16691)
• Revert "Remove which from shell invocations" (#16803)
• tests/gnrc_dhcpv6_client: Fix for newer Kea versions and remove sudo
  requirement (#16792)
• tests/gnrc_dhcpv6_client: honor configured $IFACE in Kea config (#16796)
• tinydtls: sock_dtls: only use ifindex with link-local addresses (#16910)

Known issues

Network related issues (52)

• 6lo gnrc fragmentation expects driver to block on TX (#7474)
• 6lo: RIOT does not receive packets from Linux when short_addr is set (#11033)
• Address registration handling inappropriate (#15867)
• app/netdev: application stops working after receiving frames with
  assertion or completely without error (#8271)
• at86rf2xx: Dead lock when sending while receiving (#8242)
• at86rf2xx: lost interrupts (#5486)
• CC2538 RF overlapping PIN usage (#8779)
• core: "Invalid read of size 4" (#7199)
• cpu/esp8266: Tracking open problems of esp_wifi netdev driver (#10861)
• dist/tools/sliptty/start_network.sh: IPv6 connectivity is broken on
  PC (#14689)
• driver/mrf24j40: blocks shell input with auto_init_gnrc_netif (#12943)
• drivers/at86rf215: Incorrect channel number set for subGHz (#15906)
• DTLS examples cannot send message to localhost (#14315)
• Emcute cannot create a double-byte name (#12642)
• ethernet: Missing multicast addr assignment (#13493)
• ethos: fails to respond to first message. (#11988)
• ethos: Unable to choose global source address. (#13745)
• ethos: Unable to handle fragmented IPv6 packets from Linux kernel (#12264)
• examples/cord_ep: Dead lock when (re-)registering in callback
  function (#12884)
• examples/gnrc_border_router: esp_wifi crashes on disconnect (#14679)
• Forwarding a packet back to its link layer source should not be
  allowed (#5051)
• gcoap example request on tap I/F fails with NIB issue (#8199)
• gcoap: Suspected crosstalk between requests (possible NULL call) (#14390)
• General 802.15.4/CC2538 RF driver dislikes fast ACKs (#7304)
• gnrc ipv6: multicast packets are not dispatched to the upper layers (#5230)
• gnrc_border_router stops routing after a while (#16398)
• gnrc_icmpv6_echo: flood-pinging another node leads to leaks in own
  packet buffer (#12565)
• gnrc_ipv6: Multicast is not forwarded if routing node listens to the
  address (#4527)
• gnrc_rpl: missing bounds checks in _parse_options (#16085)
• gnrc_sock_udp: Possible Race condition on copy in application buffer (#10389)
• gomach: Resetting netif with cli doesn't return (#10370)
• ieee802154_submac: IPv6 fragmentation broken (#16998)
• LoRaWan node ISR stack overflowed (#14962)
• lwip_sock_tcp / sock_async: received events before calling
  sock_accept() are lost due to race condition. (#16303)
• Missing drop implementations in netdev_driver_t::recv (#10410)
• net: netdev_driver_t::send() doc unclear (#10969)
• netdev_ieee802154: Mismatch between radio ll address and in memory
  address (#10380)
• nrf52: Not able to add global or ULA address to interface (#13280)
• nrfmin: communication not possible after multicast ping with no
  interval (#11405)
• openthread: does not build on current Arch (#10809)
• ping6 is failing when testing with cc2538dk (#13997)
• pkg/tinydtls: auxiliary data API does not work for async sockets (#16054)
• pkg: libcoap is partially broken and outdated (#7737)
• Possible memory leak in RIOT/build/pkg/ndn-riot/app.c (#15638)
• Riot-os freezes with lwip + enc28j60 + stm32L4 (#13088)
• samr30 xpro doesn't seem to use its radio ok (#12761)
• scan-build errors found during 2019.07 testing (#11852)
• send data with UDP at 10HZ, the program die (#11860)
• stale border router does not get replaced (#12210)
• two nodes livelock sending neighbor solicitations back and forth
  between each other (#16670)
• Unclear how Router Solicitations are (or should be) handled (#15926)
• xbee: setting PAN ID sometimes fails (#10338)

Timer related issues (15)

• cpu/native: timer interrupt issue (#6442)
• misc issues with tests/trickle (#9052)
• MSP430: periph_timer clock config wrong (#8251)
• periph/timer: timer_set() underflow safety check (tracking issue) (#13072)
• periph_timer: systematic proportional error in timer_set (#10545)
• saml21 system time vs rtc (#10523)
• Sleep mode for Arduino (#13321)
• stm32_common/periph/rtc: current implementation broken/poor accuracy (#8746)
• sys/newlib: gettimeofday() returns time since boot, not current wall
  time. (#9187)
• tests: xtimer_drift gets stuck on native (#6052)
• xtimer mis-scaling with long sleep times (#9049)
• xtimer: add's items to the wrong list if the timer overflows between
  _xtimer_now() and irq_disable() (#7114)
• xtimer_set_msg: crash when using same message for 2 timers (#10510)
• xtimer_usleep stuck for small values (#7347)
• xtimer_usleep wrong delay time (#10073)

Drivers related issues (17)

• (almost solved) SPI SD-Card driver: SPI initialisation freeze until
  timeout (#14439)
• adc is not a ADC-Driver but a analog pin abstraction (#14424)
• at86rf2xx: Simultaneous use of different transceiver types is not
  supported (#4876)
• cpu/msp430: GPIO driver doesn't work properly (#9419)
• driver/hts221: Temperature and Humidity readings incorrect (#12445)
• ESP32 + DHT + SAUL reading two endpoints causes freeze. (#12057)
• examples/dtls-wolfssl not working on pba-d-01-kw2x (#13527)
• fail to send data to can bus (#12371)
• floats and doubles being used all over the place. (#12045)
• mdt_erase success, but vfs_format resets board (esp32-heltec-
  lora32-v2) (#14506)
• periph/spi: Switching between CPOL=0,1 problems on Kinetis with
  software CS (#6567)
• periph: GPIO drivers are not thread safe (#4866)
• Potential security and safety race conditions on attached devices (#13444)
• PWM: Single-phase initialization creates flicker (#15121)
• STM32: SPI clock not returning to idle state and generating
  additional clock cycles (#11104)
• TCP client cannot send read only data (#16541)
• Two bugs may lead to NULL dereference. (#15006)

Native related issues (6)

• examples/ccn-lite: floating point exception while testing on native (#15878)
• examples/micropython: floating point exception while testing on
  native (#15870)
• native getchar is blocking RIOT (#16834)
• native not float safe (#495)
• native: tlsf: early malloc will lead to a crash (#5796)
• SIGFPE on native architecture when printing double floats on Ubuntu
  21.04 (#16282)

Other platforms related issues (23)

• Failing tests on FE310 (Hifive1b) (#13086)
• [TRACKING] Fixes for automatic tests of ESP32 boards. (#12763)
• arm7: printf() with float/double not working (#11885)
• boards/hifive1: flashing issue (#13104)
• Cannot use LLVM with Cortex-M boards (#13390)
• cpu/cortexm_common: irq_enable returns the current state of
  interrupts (not previous) (#10076)
• cpu/sam0: flashpage write / read cycle produces different results
  depending on code layout in flash (#14929)
• cpu/stm32f1: CPU hangs after wake-up from STOP power mode (#13918)
• esp32-wroom-32: tests/netstats_l2 failing sometimes (#14237)
• esp32: can't use newer C++ standard than c++11 (#15685)
• esp8266 precompiled bootloaders don't support partitions past 1MB (#16402)
• esp8266: Hangs when erasing spi sector on mtd0 if using esp_wifi (#16281)
• gcoap/esp8266: Stack overflow with gcoap example (#13606)
• I found stm32 DMA periph driver bugs! when I tested stm32l431rc
  board. (#16242)
• Incorrect default $PORT building for esp32-wroom-32 on macOS (#10258)
• MIPS: toolchain objcopy doesn't work and no .bin can be generated (#14410)
• MPU doesn't work on cortex-m0+ (#14822)
• periph_timer: Test coverage & broken on STM32F767ZI (#15072)
• riscv: ISR stack is too small for ENABLE_DEBUG in core files (#16395)
• stm32152re: hardfault when DBGMCU_CR_DBG* bits are set and branch
  after __WFI() (#14015)
• stm32f7: Large performance difference between stm32f746 and stm32f767 (#14728)
• sys/riotboot/flashwrite: unaligned write when skipping
  RIOTBOOT_MAGIC on stm32wb (#15917)
• tests/mpu_noexec_ram: fails on i-nucleo-lrwan1 (#14572)

Build system related issues (15)

• buildtest uses wrong build directory (#9742)
• make -j flash fails due to missing make dependencies or make flash-only rebuilds the .elf (#16385)
• Build dependencies - processing order issues (#9913)
• build: info-build doesn't work with boards without port set (#15185)
• BUILD_IN_DOCKER ignores USEMODULE (#14504)
• Different build behavior between murdock and
  riot/riotbuild:latest image (#9645)
• dist/tools/cppcheck/cppchck.sh: errors when running with Cppcheck
  1.89 (#12771)
• doxygen: riot.css modified by 'make doc' (#8122)
• LTO broken (binaries too large) (#16202)
• macros: RIOT_FILE_RELATIVE printing wrong file name for headers (#4053)
• make: ccache leads to differing binaries (#14264)
• make: Setting constants on compile time doesn't really set them
  everywhere (#3256)
• make: use of immediate value of variables before they have their
  final value (#8913)
• Tracking: remove harmful use of export in make and immediate
  evaluation (#10850)
• Windows AVR Mega development makefile Error (#6120)

Other issues (45)

• [TRACKING] sys/shell refactoring. (#12105)
• _NVIC_SystemReset stuck in infinite loop when calling pm_reboot
  through shell after flashing with J-Link (#13044)
• make term no longer works with JLinkExe v6.94 (#16022)
• make term output is inconsistent between boards, ethos and
  native (#12108)
• assert: c99 static_assert macro doesn't function for multiple
  static_asserts in the same scope (#9371)
• Basic test for periph/rtt introduced in #15431 is incorrect (#15940)
• boards/esp32-wroom-32: tests/mtd_raw flakey (#16130)
• Bug: openocd 0.10.0-6 Ubuntu dies while debugging with -rtos auto (#13285)
• C++11 extensions in header files (#5561)
• Can't build relic with benchmarks or tests (#12897)
• CC2538DK board docs: broken links (#12889)
• edbg: long lines flooded over serial become garbled (#14548)
• examples / tests: LoRa tests fail on platforms that don't support
  LoRa (#14520)
• File systems report names with leading slashes (#14635)
• flashing issue on frdm-k64f (#15903)
• Gcoap drops long packages instead of gracefully erring out (#14167)
• gcoap_dtls: Selecting transport at run time is not possible (#16674)
• I2C not working under RIOT with U8G2 pkg (#16381)
• ieee802154_security: Nonce is reused after reboot (#16844)
• Making the newlib thread-safe (#4488)
• nanocoap: incomplete response to /.well-known/core request (#10731)
• Order of auto_init functions (#13541)
• pkg/tinydtls: Multiple issues (#16108)
• Possible memset optimized out in crypto code (#10751)
• Potential race condition in compile_and_test_for_board.py (#12621)
• pyterm on stdio_cdc_acm stops working after a few seconds (#16077)
• RIOT cannot compile with the latest version of macOS (10.14) and
  Xcode 10 (#10121)
• RIOT is saw-toothing in energy consumption (even when idling) (#5009)
• riotboot/nrf52840dk: flashing slot1 with JLINK fails (#14576)
• Sam boards: isr_eic call all IRQ raised without taking into account
  their status (enabled/disabled) (#16978)
• scheduler: priority inversion problem (#7365)
• sys/fmt: Missing tests for fmt_float, fmt_lpad (#7220)
• sys/riotboot: documentation issues (#11243)
• sys/stdio_uart: dropped data when received at once (#10639)
• tests/cpp11_*: failing on i-nucleo-lrwan1 (#14578)
• tests/lwip target board for python test is hardcoded to native (#6533)
• tests/pkg_libhydrogen: test fails on master for the samr21-xpro with
  LLVM (#15066)
• tests/pkg_tensorflow-lite: tests randomly failing on nrf52dk and
  esp32-wroom-32 (#13133)
• tests/test_tools: test fails while testing on samr21-xpro/iotlab-m3 (#15888)
• tests/thread_float: crashes on avr-rss2 (#16908)
• tests: broken with stdio_rtt if auto_init is disabled (#13120)
• tests: some tests don't work with newlib lock functions. (#12732)
• Tracker: Reduce scope on unintended COMMON variables (#2346)
• usb-serial/list-ttys.sh: Broken when a debugger offers multiple
  serial ports (#15814)
• Use of multiple CAN bus on compatible boards (#14801)

There are 173 known issues in this release

Fixed Issues since the last release (2021.07)

• make check_bindist fails to find reference to main (#16977)
• dhcpv6_client: no prefix on downstream interface via IA_PD (#16971)
• Deleted or non selected source files are linked in (#16942)
• tests/thread_float: broken on AVR (#16896)
• Kconfig/tinydtls: Unable to compile examples/dtls-sock with
  CONFIG_DTLS_ECC enabled (#16873)
• particle: error while flashing using Docker build and DFU mode (#16749)
• test/pkg_u8g2: using SDL is failing (#16714)
• cpu/saml21: can't set baud rate on SERCOM5 (#16692)
• sam0_eth: extremely long time to RX (frames stuck in buffer?) (#16451)
• w5100 driver's improvement (#16417)
• border_router: significant packet loss when sending out packets using
  USB cdc-ecm on nrf52 (#16411)
• XFA support on AVR and MSP430 broken with binutils 2.36.1 (#16251)
• SDL2 does not work due to missing getpid (#13501)
• hello-world example crashes on BOARD=nucleo-f446re (#9775)

14 fixed issues since last release (2021.07)

Acknowledgements

We would like to thank all companies that provided us with hardware for porting
and testing RIOT-OS. Further thanks go to companies and institutions that
directly sponsored development time. And finally, big thanks to all of you
contributing in so many different ways to make RIOT worthwhile!

More information

http://www.riot-os.org

IRC, Matrix and Forum

• Join the RIOT Matrix room at: #riot-os:matrix.org
• Join the RIOT Forum at: forum.riot-os.org

License

• The code developed by the RIOT community is licensed under the GNU Lesser
  General Public License (LGPL) version 2.1 as published by the Free Software
  Foundation.
• Some external sources and packages are published under a separate license.

All code files contain licensing information.