Release 42.1

* Support for DMA4 "large address" controllers of the Raspberry Pi 4
* dmachannel: Can allocate DMA4 channel with DMA_CHANNEL_EXTENDED
* usb/xhcidevice: Newer RPi 4 (8GB) need additional mailbox call
* net: CSocket::Send(?, ?, 0) blocks, until TCP TX queue is empty
* FIXED: net/dnsclient: Parsing uncompressed answer records
* addon/wlan: Submodule hostap updated
* Recommended firmware revision updated
* FIXED: Doxyfile: Invalid WLAN path in EXCLUDE

Step 42 of Circle

* Add experimental WLAN support and sample in addon/wlan/
* addon/SDCard: Use SDHOST interface on RPi 1-3 and Zero
* System option USE_SDHOST added
* addon/SDCard: Use EMMC2 on RPi 4
* koptions: "usbspeed=full" added
* Add setjmp() and longjmp()
* util: Add strncasecmp(), strtoull() and atoi()
* CString::FormatV() supports "%llu" etc. with STDLIB_SUPPORT >= 1
* CString: Implement '#' (alternate) flag character
* addon/fatfs: Enable FF_USE_STRFUNC
* FIXED: Did not start with -O3 and AArch64
* Rules.mk: Use python3 to run serial boot tools now

Release 41.2

* CI2CMaster: Support additional devices of RPi 4
* Update sample/32-i2cshell to use additional I2C devices
* CSPIMaster: Support additional devices of RPi 4
* CSerialDevice: Support additional devices of RPi 4
* Add software profiling library to addon/profile/
* i2cslave: Supported on Raspberry Pi 4
* net: Improve ARP and ICMP handling
* net/dhcpclient: Add host name option to request
* Construct CMemorySystem object early in sysinit() in any case
* CTimer::RegisterPeriodicHandler() callable four times
* May manually acknowledge GPIO event detect status
* sound: Swap stereo channels, where it is necessary
* CLogger: SetNewTarget() added
* class CVCHIQSoundBaseDevice can be destroyed now
* bcm54213: Properly reset device in destructor
* exceptionstub: Remove superfluous GIC FIQ acknowledge
* exceptionstub64: Fix SMCStub
* net/transportlayer: Fix freeze in Connect() with multi-core
* net/ntpdaemon: Keep own copy of NTP server hostname
* linux/kthread: Non-kthread tasks can be used together with kthreads
* Add system option HEAP_BLOCK_BUCKET_SIZES
* Recommended firmware revision updated
* Doxygen documentation improved
* doc/bootloader.txt added

Hotfix: Bootloader did not work on Raspberry Pi 1 and Zero

Step 41 of Circle

* High memory support for RPi 4 added (see doc/new-operator.txt)
* System options HEAP_DEFAULT_{NEW|MALLOC} added
* xHCI driver supports RemoveDevice() and ReScanDevices()
* sample/39-umsdplugging added
* class CQEMUHostFile added to addon/qemu/
* sample addon/qemu/hostlogdemo added
* System option LEAVE_QEMU_ON_HALT added
* set_qemu_exit_status() added
* class CConsole can be used with two alternate devices
* All make-files enabled for header file dependency checking
* All system options can be defined in Config.mk (DEFINE += -DOPTION)
* Network performance vastly improved on RPi 4 AArch64
* FIXED: Dispmanx API did not work on Raspberry Pi 4
* FIXED: Possible infinite loop in CVCHIQSoundBaseDevice::Cancel()
* FIXED: CPWMSoundBaseDevice did not work with newer firmware on RPi 4
* Bluetooth support removed for legal reasons
* Recommended toolchain is based on GCC 9.2.1 now
* Recommended firmware revision updated
* tools/template: Geany project file added
* doc/qemu.txt updated
* CHANGELOG.md added

Release 40.1

* FIQ supported on Raspberry Pi 4 with AArch64 (requires ARM stub)
* Source of ARM stub armstub8-rpi4.bin added to boot/armstub/
* config.txt required for AArch64 mode
* boot/Makefile downloads specific firmware revision now
* class CUserTimer supported on Raspberry Pi 4
* addon/fatfs/ updated to FatFs R0.14 + patch1
* addon/littlevgl updated to v6.1.1
* Logging from LittlevGL implemented
* System option SCREEN_HEADLESS added
* Build option GC_SECTIONS allows garbage collection on sections
* FIXED: CI2SSoundBaseDevice didn't work with chunk size == 32
* Using -mcpu instead of -march and -mtune for build
* FIXED: Mac hangs on serial close in flasher.py and reboottool.py
* lib/bt/ is not build from makeall any more
* GNU Toolchain 8.3-2019.03 referenced in README.md

Step 40 of Circle

* Support for Raspberry Pi 4 Model B added
* GIC-400 supported (FIQ on AArch32 only)
* class CBcm54213Device implemented
* PCIe Host Bridge driver added
* Address map updated for access to xHCI controller
* USB xHCI driver implemented
* Automatic GPIO clock source and divider selection added
* DelayLoop and SpeedFactor re-tuned

Release 39.2

* addon/littlevgl/ (LittlevGL v6.0 support) added
* SD card access is faster now
* UMSD device removal on request added
* Can speed up network initialization now
* Back-light level of Official Touchscreen can be set
* Can query SD card ID from CEMMCDevice now
* CScreenDevice::GetFrameBuffer() added
* System option SAVE_VFP_REGS_ON_IRQ/FIQ supported with AARCH=64
* System option SERIAL_GPIO_SELECT added
* addon/fatfs/ updated to FatFs R0.13c + patch1/2/3/4
* Recommended toolchain is GNU-C 8.2.1 based now

Release 39.1

* In-memory kernel update (chain boot) support added
* class CHTTPDaemon supports content type "multipart/form-data"
* sample/38-bootloader added
* AArch64 C++ exception handling supported with circle-stdlib
* DMA channel resource management added
* DMA lite engines are supported
* class CScreenDevice uses DMA to speed-up scrolling
* ARMv7 Generic Timer supported on RPi 2/3 (qemu-system-aarch64 works)
* USE_PHYSICAL_COUNTER is default
* CGPIOPin::WriteAll() added
* FIXED: USB power delay on root port too small
* Target "install" added to Rules.mk
* Optional Config2.mk file included from Rules.mk
* tools/bootloader updated (record type 4 and length % 4 != 0 allowed)

Step 39 of Circle

* VC4 accelerated graphics support added to addon/vc4/interface/
* Supports EGL 1.4, OpenGL ES 1.1 and 2.0, OpenVG 1.1 and Dispmanx APIs
* <math.h> functions can be used with STDLIB_SUPPORT = 1
* Can re-scan for new USB devices on application request now
* Compute Module 3+ support added
* FIXED: Wrong stack alignment on exceptions in some cases
* FIXED: Act LED did not work with Compute Module 3
* FIXED: Possible compile errors with STDLIB_SUPPORT >= 2