RIOT-2020.04 - 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, soft
real-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 2020.04 release includes:

Add support for 6LoWPAN IPv6 extension header next header compression
Add support for DHCPv6 prefix delegation client
Add support for kw41zrf and at86rf215 IEEE 802.15.4 radios
Improvements on power management for ESP32
Improvements and extensions in support of fe310 and lpc2387
lwIP: provide support for asynchronous sock
Improvements on xtimer module and testing
Initial addition of the new timer subsystem: ztimer
Migration to Kconfig - phase I: add multiple GNRC and system modules
+10 new boards, +11 new drivers, +7 new packages

555 pull requests, composed of 1514 commits, have been merged since the
last release, and 22 issues have been solved. 60 people contributed with
code in 102 days. 3346 files have been touched with 358398 (+) insertions and
184720 deletions (-).

Notations used below:

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

New features and changes

System libraries

* core:
    + add optional support for executable space protections
    * sched: sched.h: remove not needed bitarithm include to avoid conflict
    + turn kernel_init.c and panic.c into submodules of core
+ sys/auto_init: allow delayed initialization of SAUL & gnrc_netif
* sys/base64: implement Base 64 Encoding with URL and Filename Safe Alphabet
* sys/crypto: define cipher using a module instead of CFLAGS
* sys/crypto/modes/ccm: handle input_len = 0
* sys/ecc: fix assertion in golay2412
* sys/event:
    + add event_wait_timeout64()
    + add shared event threads
* sys/newlib:
    + enable multiple heaps in _sbrk_r()
    * syscalls_default: update heap_stats for multiple heaps
* sys/puf_sram: counter based seed after soft reset
* sys/phydat: improvement of phydat_dump including test application
* sys/shell:
    + add rtt command
    * correctly detect and handle long lines
+ sys/shell_commands: + provide command to print version
* sys/spp: randomize canary value on each build
* sys/suit:
    * cleanup of TinyCBOR to NanoCBOR refactor
    * coap: make use of exposed tree handler function
    * update to draft-ietf-v3
+ sys/uri_parser: initial import of a minimal and non-destructive URI parsing
* sys/usb: use default VID/PID for RIOT-included peripherals
* sys/xtimer:
    * set now pointer correctly in _update_short_timers() loop
    + add xtimer_set_timeout_flag64()
    * xtimer_mutex_lock_timeout fix with short timeout
+ sys/ztimer: initial import

Networking

* net/coap:
    * deprecate gcoap_add_qstring() and update uses
    + Packet API function to add Uri-Query option
+ net/dhcpv6: initial implementation of a client (with IA_PD support)
* net/dns: fix DNS resolution in ping6
* net/gcoap:
    + add canonical uri query function names
    + allow proxied client requests
    * use sock_async and events
+ net/gnrc_dhcpv6_client_6lbr: initial import of a 6LBR DHCPv6 client
+ net/gnrc_ipv6_ext_frag: initial import of statistics module
* net/gnrc_ipv6_nib:
    * do not ignore prefix list for route resolution
    * fix border router with DNS & Context Compression
    * only route to prefix list entry if on-link
* net/gnrc_lorawan:
    * fix the handling of downlink frames without payload
    * remove netdev layer from MAC
* net/gnrc_netif:
    + add gnrc_netif_send and gnrc_netif_highlander functions
    * implementation of dynamic GNRC_NETIF_NUMOF approach
* net/gnrc_nettype: deprecate IOVEC type
* net/gnrc_pktbuf: deprecate gnrc_pktbuf_replace_snip()
+ net/gnrc_sixlowpan_iphc: add support for IPv6 extension header compression
+ net/gnrc_sock: provide implementation for `sock_*_recv_buf()`
* net/gnrc_sock_udp: choose random ephemeral port
- net/gnrc_tftp: remove module
* net/gnrc_uhcpc:
    * ensure compression context is managed by the ABR
    * only configure 6Lo-ND features if wireless-interface is 6LN
    * update compression context with new prefix
* net/nanocoap:
    + add coap_opt_add_uquery2() with parameter key value length
    + add convenience function for adding path elements
    * add uquery improvements
    * make separate tree handling function
    - remove obsolete functions for addition of Uri-Query option
+ net/netdev: add netdev_trigger_event_isr() function
- net/nhdp: remove module
+ net/sock:
    * async: add optional callback argument
    + amend with zero-copy receive functions
    + amend API to iterate over stack-internal buffer chunks

Packages

+ pkg/cmsis-nn: add support
+ pkg/cryptoauthlib: add support
+ pkg/libbase58: add support
- pkg/libcose: remove monocypher crypto mode
+ pkg/littlefs2: add support for LittleFS v2.x.y
+ pkg/lvgl: add initial support for LittlevGL
* pkg/lwip:
    + add auto-init support for transceiver ENC28J60
    + provide sock_async support
* pkg/micropython: bump version for FreeBSD fix
* pkg/monocypher: bump to version 3.0.0
* pkg/nanopb: bump version to 0.4.1
* pkg/nimble/autoconn: various improvements
- pkg/oonf_api: remove support
+ pkg/qcbor: add support
* pkg/tinydtls: remove receive buffer indirection via mbox
* pkg/wolfssl: bump version to 4.3.0
+ pkg/yxml: add support Yxml XML parser library package

Boards

* boards: include common dfu logic where applicable
+ boards/adafruit-clue: add initial support
* boards/arduino-mkr: feather-m0: sodaq-*: provide stdio over USB and
  setup automatic flash with bossa
+ board/arduino-nano-33-ble: add initial support
+ boards/cc1312-launchpad: add support and documentation
* boards/feather-nrf52840:
    * use CDC ACM as default STDIO
    * fix LED macros
+ boards/esp32-heltec-lora32-v2: add support
+ boards/im880b: add support
+ boards/kw41z-mini: add support
* boards/mega-xplained: fix ADC line definitions
* boards/nrf51: fix UART hardware flow-control configuration
* boards/nucleo-l152re: fix uart1 pinout config
+ boards/nucleo-l412kb: add initial support
* boards/sam[r/d]21-xpro: prefer XOSC32K for RTC/RTT (GCLK2)
* boards/same54-xpro:
    * configure remaining EXT connectors
    * don't source peripheral clocks from main clock
* boards/samr30: add helper for antenna switch
* boards/stm32l4: add common clock configuration
+ boards/olimexino-stm32: add support
+ boards/openlabs-kw41z-mini-256kib: add support
* boards/openmote-b: add SAUL configuration and note about flashing
+ boards/p-nucleo-wb55: add initial support
+ boards/pic32*: add GPIO SAUL configuration
* boards/pinetime:
    * add defines for controlling the backlight pin
    * update mtd_spi_nor config
    * fix battery ADC line define
* doc/doxygen:
    + add 'Creating boards' section
    * improvements on various board's documentation

CPU

* cpu:
    * add CPU feature for stack smash protections
    + add UART RX implementation on PIC32 devices
    * make default idle/main stacksizes configurable on all archs
    * move cpu level dependencies in dedicated Makefile.dep files
    * unify UART hardware flow control use to a generic module
* cpu/atmega_common: fix reboot issues
* cpu/cc13x2: rename cpu to cc26x2_cc13x2
* cpu/cc2538:
    * fix spi_transfer_bytes()
    + implement periph/pm
    * timer: handle power mode
* cpu/cc26xx_cc13xx: add power common code
* cpu/cortexm:
    + add support for Cortex-M interrupt sub-priorities
    * cleanup dependencies
    * move CPU_ARCH/FAM to Makefile.features
    * only enable MPU during low low level init
* cpu/efm32:
    * cleanup of makefiles
    * fix incorrect ADC status register
* cpu/esp_common:
    * allow WiFi modem sleep mode
    + esp-wifi: allow connecting to open networks
    * fixes in common CPU configurations
    * move dependency resolutions to Makefile.dep
* cpu/esp32:
    * activate automatic XTAL detection
    + add support for light/deep sleep and pm_layered
    * allow external 32 kHz crystal for the RTC hardware time
    + esp_wifi: add WPA2 enterprise mode with IEEE 802.1x/EAP authentication
    * fix wake-up sources for sleep mode
+ cpu/esp8266: add RTT implementation
* cpu/fe310:
    * fix power management configuration
    + implement driver for watchdog
* cpu/lpc2387:
    * fix RTC leap year calculation
    + implement periph/adc
    + implement periph/i2c
    * make SPI configurable
* cpu/native: fix c11_atomic sizes on FreeBSD
* cpu/native/can/candev_linux: add check for real can
+ cpu/nrf52/nRF802154: implement CCA
+ cpu/nrf5x: add and enable configuration for the built-in DC/DC converter
* cpu/sam0:
    + add gpio_disable_mux() function
    + add samd21j17d support
    * enhance power saving by switching EIC clock source during STANDBY mode
    * fix handling of PM_NUM_MODES
    + provide interface to query GCLK frequency
    * use generic exti_config
* cpu/samd21: pwm: allow to use channels > 3
* cpu/samd5x: disable RTC on init to prevent undefined RTC state
* cpu/[saml21/1x]: enable buck voltage regulator when possible
* cpu/stm32_common:
    + add USB OTG FS/HS usbdev peripheral driver
    * enable EXTI interrupt for rtt
    * eth: fix address and multicast filtering
* cpu/stm32f1: make RTC Y2038 safe
+ cpu/stm32wb: add initial support

Device Drivers

* doc: various fixes in driver documentation
+ drivers/apds99xx: add support for APDS99XX ambient light and proximity sensors
+ drivers/at24cxxx: add support for AT24Cxxx family of EEPROMs
+ drivers/at24mac: add support for unique ID chip
+ drivers/at25xx: add support for AT25xxx family of EEPROMs
+ drivers/at86rf215: add basic support for AT86RF215 dual-band radio
* drivers/at86rf2xx:
    * fix receive before send detection
    + implement basic mode
+ drivers/bh1900nux: add support
+ drivers/bme680: add support
+ drivers/can: add CAN support for nucleo-l476rg
+ drivers/cc110x: add support for promiscuous mode
+ drivers/disp_dev: add generic interface for display drivers
* drivers/ds18: fix temperature conversion
+ drivers/hmc5883l: add support for Honeywell HMC5883L magnetometer
+ drivers/kw41zrf: add support for radio
+ drivers/lis2dh12: add interrupt functionality
* drivers/mtd_spi_nor: erase timings in struct
+ drivers/periph_common/rtc: add rtc_mktime() & rtc_localtime() helper functions
+ drivers/rtt_rtc: add RTT-based RTC implementation, enable it for cpu/cc2538,
  nrf5x_common
* drivers/slipdev: provide stdio multiplexing over SLIP
+ drivers/sps30: add support for particulate matter sensor
* drivers/srf08: cleanup driver configuration scheme
+ drivers/stmpe811: add support for touchscreen controller
* drivers/ws281x:
    + add support for esp32
    + add VT100 backend for native

Build System / Tooling

* build system: Restructure dependency resolution
* dist:
    * cc2538-bsl: use upstream version
    + dhcpv6-pd_ia: initial import of a DHCPv6 server bootstrapper
    * edbg: update to latest upstream version
    * factor out static tests from build_and_test
    * packer: update vagrant image to Ubuntu 18.04 + refactoring
    + sliptty: introduce a new SLIP to TUN tool
    * sliptty/start_network.sh: configure global address for SLIP interface
    * testbed-support:
        * fix compatibility with cli-tools v3
        * use BINFILE for flashing on iotlab
+ doc: add section on configuration to 'Getting started'
* make:
    * disable implicit rules
    * remove support for make <4
    * native: turn on creation of debug symbols (CFLAGS += -g)
* Makefile:
    * arch: mips: Allow CFLAGS_DBG and CFLAGS_OPT to be overridden
    * boards: move remaining uses of USEMODULE from Makefile.include to
      Makefile.dep
    * disable stdio_% modules before they are included
    * fix duplicate modules from USEMODULE
    * fix sock_udp deps for stnp
    * include package deps earlier
    * info-global.inc.mk: reset BOARDSDIR
    * Makefile.dep: remove usage of DEFAULT_MODULE += stdio%
    * mips: cleanup include makefile
    * move cpu level dependencies in dedicated Makefile.dep files
    * periph_init based on USEMODULE
    * pkg/local.mk: add FORCE target to .PHONY
    + provide CPU as a feature
    * use simple expansion for widely used variables

Testing

* tests:
    + add check_unittests helper function
    + add interactive_sync adapted to shell
    * fix compilation problems with NDEBUG
    * fix for `GNRC_NETIF_SINGLE`
    * fixes for evtimer_msg and bench_runtime_coreapis
+ tests/bench_xtimer_load: initial commit
* tests/buttons: fix build failure if BTN0_PIN is not declared
+ tests/candev: add initial version with native support
+ tests/driver_netdev_common: add compile-test for network drivers
+ tests/emcute: provide tests
+ tests/gnrc_ipv6_nib_dns: add test of RDNSS option handling
* tests/gnrc_rpl_srh: use AsyncSniffer for sniffing
* tests/periph_rtc: fix system locks in ISR
+ tests/xtimer_overhead: initial commit

Kconfig migration

Migration to Kconfig as configuration tool is currently on phase 1. Which means
that we are moving configuration options from modules to Kconfig files, and
leaving its use optional.

+ doc: add Kconfig section
* Kconfig:
    * add CPU and Board common symbols
    * add Drivers menu
    * include application-specific symbols first
    * net/gnrc/ipv6: group IPv6 related Kconfig options
+ Expose configurations to Kconfig of:
    + drivers/periph/wdt
    + drivers/mrf24j40
    + net/gcoap
    + net/gnrc/ipv6/ext/frag
    + net/gnrc/ipv6/nib
    + net/gnrc/sixlowpan
    + net/ieee802154
    + net/nanocoap
    + pkg/tinydtls
    + pkg/wakaama
    + sys/usbus
    + usbus/cdc/acm

API Changes

SUIT: update to draft-ietf-v3
Makefile.include: remove support for make <4
net/gnrc_netif: implementation of dynamic GNRC_NETIF_NUMOF approach
net/sock: amend with zero-copy receive functions:

+ /**
+  * @brief   Releases the stack-internal buffer space provided by the
+  *          `sock_*_recv_buf()` functions.
+  * @param[in] buf_ctx   Stack-internal buffer context to release.
+  */
+ void sock_recv_buf_free(void *buf_ctx);

+ /**
+  * @brief Decrypts and provides stack-internal buffer space containing a
+  *        message from a remote peer.
+  *
+  */
+ ssize_t sock_dtls_recv_buf(sock_dtls_t *sock, sock_dtls_session_t *remote,
+                            void **data, void **buf_ctx, uint32_t timeout);

+ /**
+ * @brief   Provides stack-internal buffer space containing an IPv4/IPv6
+ *          message from remote end point
+ */
+ ssize_t sock_ip_recv_buf(sock_ip_t *sock, void **data, void **buf_ctx,
+                         uint32_t timeout, sock_ip_ep_t *remote);

+ /**
+  * @brief   Provides stack-internal buffer space containing a UDP message from
+  *          a remote end point
+  */
+ ssize_t sock_udp_recv_buf(sock_udp_t *sock, void **data, void **buf_ctx,
+                           uint32_t timeout, sock_udp_ep_t *remote);

net/sock/async: add optional callback argument:

+ * @param[in] arg   Argument provided when setting the callback using
+ *                  @ref sock_dtls_set_cb(). May be NULL.
  */
- typedef void (*sock_dtls_cb_t)(sock_dtls_t *sock, sock_async_flags_t flags);
+ typedef void (*sock_dtls_cb_t)(sock_dtls_t *sock, sock_async_flags_t flags,
+                                void *arg);

+ * @param[in] arg   Argument provided when setting the callback using
+ *                  @ref sock_ip_set_cb(). May be NULL.
  */
- typedef void (*sock_ip_cb_t)(sock_ip_t *sock, sock_async_flags_t flags);
+ typedef void (*sock_ip_cb_t)(sock_ip_t *sock, sock_async_flags_t flags,
+                              void *arg);

+ * @param[in] arg   Argument provided when setting the callback using
+ *                  @ref sock_tcp_set_cb(). May be NULL.
  */
- typedef void (*sock_tcp_cb_t)(sock_tcp_t *sock, sock_async_flags_t flags);
+ typedef void (*sock_tcp_cb_t)(sock_tcp_t *sock, sock_async_flags_t flags,
+                               void *arg);

+ * @param[in] arg   Argument provided when setting the callback using
+ *                  @ref sock_tcp_queue_set_cb(). May be NULL.
  */
  typedef void (*sock_tcp_queue_cb_t)(sock_tcp_queue_t *queue,
-                                     sock_async_flags_t flags);
+                                     sock_async_flags_t flags,
+                                     void *arg);

+ * @param[in] arg   Argument provided when setting the callback using
+ *                  @ref sock_udp_set_cb(). May be NULL.
  */
- typedef void (*sock_udp_cb_t)(sock_udp_t *sock, sock_async_flags_t type);
+ typedef void (*sock_udp_cb_t)(sock_udp_t *sock, sock_async_flags_t type,
+                               void *arg);

net/sock/dns: make sock_dns_query() return the length of the address:

/**
 * @brief Get IP address for DNS name
 *
- * @return      0 on success
- * @return      !=0 otherwise
+ * @return      the size of the resolved address on success
+ * @return      < 0 otherwise
 */
int sock_dns_query(const char *domain_name, void *addr_out, int family);

mtd_spi_nor: move const params to separate struct:

+ /**
+  * @brief Compile-time parameters for a serial flash device
+  */
+ typedef struct {
+     const mtd_spi_nor_opcode_t *opcode; /**< Opcode table for the device */
+     spi_clk_t clk;           /**< SPI clock */
+     uint16_t flag;           /**< Config flags */
+     spi_t spi;               /**< SPI bus the device is connected to */
+     spi_mode_t mode;         /**< SPI mode */
+     gpio_t cs;               /**< CS pin GPIO handle */
+     uint8_t addr_width;      /**< Number of bytes in addresses, usually 3 for small devices */
+ } mtd_spi_nor_params_t;
+

 typedef struct {
     mtd_dev_t base;          /**< inherit from mtd_dev_t object */
-    const mtd_spi_nor_opcode_t *opcode; /**< Opcode table for the device */
-    spi_t spi;               /**< SPI bus the device is connected to */
-    gpio_t cs;               /**< CS pin GPIO handle */
-    spi_mode_t mode;         /**< SPI mode */
-    spi_clk_t clk;           /**< SPI clock */
-    uint16_t flag;           /**< Config flags */
+    const mtd_spi_nor_params_t *params; /**< SPI NOR params */
     mtd_jedec_id_t jedec_id; /**< JEDEC ID of the chip */
     uint32_t page_addr_mask;
     uint32_t sec_addr_mask;
-    uint8_t addr_width;      /**< Number of bytes in addresses, usually 3 for small devices */
     uint8_t page_addr_shift;
     uint8_t sec_addr_shift;
 } mtd_spi_nor_t;

Deprecations

Warnings

make all-debug target will be removed for native after the 2020.10 release
net/gcoap: gcoap_add_qstring() will be removed after the 2020.10 release
net/gnrc/nettype: GNRC_NETTYPE_IOVEC type will be removed after 2020.10
release
net/gnrc_pktbuf: gnrc_pktbuf_replace_snip() will be removed after 2020.10
release
net/gnrc/sixlowpan: Configuration macro
GNRC_SIXLOWPAN_FRAG_RBUF_AGGRESSIVE_OVERRIDE will be removed after 2020.10
release.

Removals

Makefile.include: remove support for GNU make <4
pkg/oonf_api: remove package
pkg/tinydtls: remove TINYDTLS_LOG configuration macro
sys/net/gnrc_tftp: remove module
sys/net/nhdp: remove module

Known issues (136)

Networking related issues (48)

#13834: DHCPv6 client ends up in busy loop after a while
#13745: ethos: Unable to choose global source address.
#13496: cpu/stm32/eth, board/nucleo-f767z1: ethernet buffering issue (ping >1s)
after debug break
#13490: cpu/stm32/eth, board/nucleo-f767z1: ethernet initialisation fails
sometimes
#13209: examples/gnrc_border_router is crashing after some time
#13088: Riot-os freezes with lwip + enc28j60 + stm32L4
#12943: driver/mrf24j40: blocks shell input with auto_init_gnrc_netif
#12884: examples/cord_ep: Dead lock when (re-)registering in callback function
#12858: KW2XRF: Broken network communication without netstats-l2
#12857: examples/gnrc_networking_mac broken on ATmega
#12565: gnrc_icmpv6_echo: flood-pinging another node leads to leaks in own
packet buffer
#12264: ethos: Unable to handle fragmented IPv6 packets from Linux kernel
#12210: stale border router does not get replaced
#11988: ethos: fails to respond to first message.
#11860: send data with UDP at 10HZ, the program die
#11859: examples: dtls-echo fails silently when DTLS_ECC flag enabled
#11852: scan-build errors found during 2019.07 testing
#11795: gnrc_tftp: string functions on non-null terminated input
#11405: nrfmin: communication not possible after multicast ping with no interval
#11212: POSIX sockets + lwIP: bad file descriptor
#11033: 6lo: RIOT does not receive packets from Linux when short_addr is set
#10969: net: netdev_driver_t::send() doc unclear
#10861: cpu/esp8266: Tracking open problems of esp_wifi netdev driver
#10809: openthread: does not build on current Arch
#10410: Missing drop implementations in netdev_driver_t::recv
#10389: gnrc_sock_udp: Possible Race condition on copy in application buffer
#10380: netdev_ieee802154: Mismatch between radio ll address and in memory
address
#10370: gomach: Resetting netif with cli doesn't return
#10338: xbee: setting PAN ID sometimes fails
#9709: examples: failed assertion in dtls-echo example
#9656: gnrc/netif: various problems after resetting interface a second time
#8779: CC2538 RF overlapping PIN usage
#8752: mrf24j40: does not link for examples/default
#8271: app/netdev: application stops working after receiving frames with
assertion or completely without error
#8242: at86rf2xx: Dead lock when sending while receiving
#8199: gcoap example request on tap I/F fails with NIB issue
#8172: gnrc_netif, gnrc_uhcpc: Replacing prefix on border router results in no
configured prefix
#8086: gnrc_rpl_p2p: port to nib and fix compile errors
#7737: pkg: libcoap is partially broken and outdated
#7474: 6lo gnrc fragmentation expects driver to block on TX
#7304: General 802.15.4/CC2538 RF driver dislikes fast ACKs
#6018: nRF52: gnrc_6lowpan_ble: memory leak with nordic_softdevice_ble
#5863: OSX + SAMR21-xpro: shell cannot handle command inputs larger than 64
chars
#5748: gnrc: nodes crashing with too small packet buffer
#5486: at86rf2xx: lost interrupts
#5230: gnrc ipv6: multicast packets are not dispatched to the upper layers
#5051: Forwarding a packet back to its link layer source should not be allowed
#4527: gnrc_ipv6: Multicast is not forwarded if routing node listens to the
address

Timer related issues (17)

#13072: periph/timer: timer_set() underflow safety check (tracking issue)
#12909: Bug: Unexpected behavior with xtimer_periodic_wakeup() for large periods
on Nucleo-f401re
#11523: xtimer_periodic_wakeup crashing at high frequencies on frdm-kw41z
#11149: xtimer: hang on xtimer_spin_until (corner case)
#10545: periph_timer: systematic proportional error in timer_set
#10523: saml21 system time vs rtc
#10510: xtimer_set_msg: crash when using same message for 2 timers
#10073: xtimer_usleep wrong delay time
#9187: sys/newlib: gettimeofday() returns time since boot, not current wall
time.
#9052: misc issues with tests/trickle
#9049: xtimer mis-scaling with long sleep times
#8746: stm32_common/periph/rtc: current implementation broken/poor accuracy
#8251: MSP430: periph_timer clock config wrong
#7347: xtimer_usleep stuck for small values
#7114: xtimer: add's items to the wrong list if the timer overflows between
_xtimer_now() and irq_disable()
#6442: cpu/native: timer interrupt issue
#6052: tests: xtimer_drift gets stuck on native

Drivers related issues (9)

#13444: Potential security and safety race conditions on attached devices
#12445: driver/hts221: Temperature and Humidity readings incorrect
#12371: fail to send data to can bus
#12045: floats and doubles being used all over the place.
#11388: SD card initialization: timeouts effectively blocking
#11104: STM32: SPI clock not returning to idle state and generating additional
clock cycles
#9419: cpu/msp430: GPIO driver doesn't work properly
#8045: stm32/periph/uart: extra byte transmitted on first transmission
#4876: at86rf2xx: Simultaneous use of different transceiver types is not
supported

Native related issues (3)

#11472: Warnings from objcopy and size (binutils 2.32)
#5796: native: tlsf: early malloc will lead to a crash
#495: native not float safe

Other platforms related issues (18)

#13606: gcoap/esp8266: Stack overflow with gcoap example
#13408: Bug: PWM test crashes on Arduino Mega 2560
#13390: Cannot use LLVM with Cortex-M boards
#13267: Failing tests on MSP430 (z1)
#13104: boards/hifive1: flashing issue
#13086: Failing tests on FE310 (Hifive1b)
#12763: [TRACKING] Fixes for automatic tests of ESP32 boards.
#12651: Failing tests on AVR (tested with atmega256rfr2-xpro)
#12168: pkg/libb2: blake2s doesn't work on AVR
#12057: ESP32 + DHT + SAUL reading two endpoints causes freeze.
#10258: Incorrect default $PORT building for esp32-wroom-32 on macOS
#10122: Indeterministic hard fault in _mutex_lock(), with nRF52 SoftDevice
#10076: cpu/cortexm_common: irq_enable returns the current state of interrupts
(not previous)
#8408: pkg/fatfs: linker error when build tests/pkg_fatfs_vfs for msb430 based
boards
#7753: pic32-wifire: race-condition when linking in concurrent build
#6567: periph/spi: Switching between CPOL=0,1 problems on Kinetis with software
CS
#5774: cpu: cortexm_common: context switching code breaks when compiling with
LTO
#4954: chronos: compiling with -O0 breaks

Build system related issues (11)

#13492: make -j flash broken on esp* (will always flash the previous binary)
#13419: Can't use nimble as prefix for modules
#12771: dist/tools/cppcheck/cppchck.sh: errors when running with Cppcheck 1.89
#10850: Tracking: remove harmful use of export in make and immediate
evaluation
#9913: Build dependencies - processing order issues
#9742: buildtest uses wrong build directory
#9645: Different build behavior between murdock and riot/riotbuild:latest
image
#8913: make: use of immediate value of variables before they have their final
value
#8122: doxygen: riot.css modified by 'make doc'
#6120: Windows AVR Mega development makefile Error
#4053: macros: RIOT_FILE_RELATIVE printing wrong file name for headers

Other issues (30)

#13918: cpu/stm32f1: CPU hangs after wake-up from STOP power mode
#13527: examples/dtls-wolfssl not working on pba-d-01-kw2x
#13345: sys/xtimer: segmentation fault: in function xtimer_msg_received_timeout
#13277: Y2038 tracking issue / strategy
#13133: tests/pkg_tensorflow-lite: tests randomly failing on nrf52dk and
esp32-wroom-32
#13120: tests: broken with stdio_rtt if auto_init is disabled
#13044: _NVIC_SystemReset stuck in infinite loop when calling pm_reboot through
shell after flashing with J-Link
#12732: tests: some tests don't work with newlib lock functions.
#12205: core: atomic: Unable to compile starting with gcc 9.1.0
#12108: make term output is inconsistent between boards, ethos and native
#12105: [TRACKING] sys/shell refactoring.
#11885: arm7: printf() with float/double not working
#11243: sys/riotboot: documentation issues
#10751: Possible memset optimized out in crypto code
#10731: nanocoap: incomplete response to /.well-known/core request
#10639: sys/stdio_uart: dropped data when received at once
#10121: RIOT cannot compile with the latest version of macOS (10.14) and Xcode
10
#9882: sys/tsrb is not thread safe on AVR
#9518: periph/i2c: tracking bugs and untested acks
#9371: assert: c99 static_assert macro doesn't function for multiple
static_asserts in the same scope
#8589: Why using -F in avrdude?
#8436: Kinetis PhyNode: failed to flash binary > 256K
#7220: sys/fmt: Missing tests for fmt_float, fmt_lpad
#6533: tests/lwip target board for python test is hardcoded to native
#5769: Possible problem in scheduler
#5009: RIOT is saw-toothing in energy consumption (even when idling)
#4866: periph: GPIO drivers are not thread safe
#4488: Making the newlib thread-safe
#3256: make: Setting constants on compile time doesn't really set them
everywhere
#2346: Tracker: Reduce scope on unintended COMMON variables

There are 137 known issues in this release

Fixed Issues since the last release (2020.01)

#13920: stm32: ztimer RTT backend overflow
#13680: suit-tool runs on every build - ModuleNotFoundError: No module named
'cbor' when building anything
#13587: drivers/cc110x: Lost IRQs can lead to driver deadlock
#13471: 6ctx: incorrectly removes 6ctx context when the non-zero part of the
address matches
#13460: Makefile.dep: DEFAULT_MODULE += stdio_rtt will always load dependencies
- even if other stdio is selected
#13459: cpu/cortex-m23: gcc 9 bug when compiling c11 atomics
#13447: gnrc_sock_dns is not working
#13442: gnrc_networking not sending packets when hardware has multiple
interfaces
#13369: native:in file gnrc_rpl_p2p.c function trickle_start() has extra and
some undeclared variables.
#13358: iotlab-m3: long HW address is in reversed order
#13353: tests/unittests/tests-ecc: segfault with golay, when enabling asserts
#13309: cpu/native/can: Segmentation fault when manipulating vcan's through
socketcan
#13287: Driver for DS18B20 returns invalid values
#13265: tests: compilation of some test applications fail with NDEBUG
#13015: Quickest start does not build with vagrant
#12854: pm_reboot() not working on AVR when compiled with LTO=1
#12370: Undocumented uint8_t assumptions in nrf52840 peripherals
#12037: cpu/sam0_common: i2c baudrate calculation fails if CLOCK_CORECLOCK > 51
MHz
#11026: Recent changes effectively killed modular board designs
#8213: at86rf2xx: Basic mode and NETOPT_AUTOACK
#8130: gcoap: can't build with network stacks other than GNRC
#7020: isr_rfcoreerrors while pinging between CC2538DKs

22 fixed issues since last release (2020.01)

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

Mailing lists

RIOT OS kernel developers list
[email protected] (http://lists.riot-os.org/mailman/listinfo/devel)
RIOT OS users list
[email protected] (http://lists.riot-os.org/mailman/listinfo/users)
RIOT commits
[email protected] (http://lists.riot-os.org/mailman/listinfo/commits)
Github notifications
[email protected] (http://lists.riot-os.org/mailman/listinfo/notifications)

IRC

Join the RIOT IRC channel at: irc.freenode.net, #riot-os

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.

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Release-2020.04