* [tryboot] conditional statement + tryboot_a_b mode
* Support custom OTP mac addresses
* Increase TFTP_MAX_BLOCK_SIZE
* Stop NVMe cleanly
* Fixes for NETCONSOLE parsing and initialisation.
* Long filename support for start_file / fixup_file.
* Secure boot and display debug info on the diagnostis screen.
Enable Network Install in the default bootloader release.
This release is signed with the secure-boot key and supports
the new HTTP boot-order for downloading signed boot images for
automated provisioning systems.
Interesting changes since the last default release
* Support and bug fixes for all Compute Module variants.
* NVMe interoperability fixes
* FAT/GPT fixes and file-system performance improvements.
* Add secure-boot support for industrial applications
See https://github.com/raspberrypi/usbboot/blob/master/secure-boot-recovery/README.md
* Added ramdisk / boot.img - for RPIBOOT and secure-boot.
* Promote the recovery.bin from stable to default. This avoids an
issue where recovery.bin fails to load on large FAT32 boot partions with
32K clusters.
Interesting changes since the last default release:-
* Display VC_BUILD_ID strings instead of the SHA256 hash
* Add support for [cm4] and [pi400] config conditionals filters.
* Change network boot to use the same "RXID" Ethernet PHY configuration as the 5.10 kernel
* TFTP - reply to duplicate ACKS
* Skip rendering of HDMI diagnostics display for the first 8 seconds unless an error occurs.
* UDP checksum fixes
* Add support for the BCM2711 XHCI controller - BOOT_ORDER 0x5
* XHCI protocol layer fixes for non-VLI controllers
* Avoid USB MSD timeout of there is only one device
* Implement tryboot for OS upgrade fallback
* Check the update-timestamp before applying an update in SELF-UPDATE mode
* Update recovery.bin to 2021-04-13 release for error pattern fix
on SDRAM failure.
Select the recovery.bin to use according to FIRMWARE_RELEASE_STATUS
in order to allow a beta test version of recovery.bin to be provided
without risking breaking the stable version of recovery.bin
