Tested on Raspberry Pi 4 B+.
1. Download latest 14-CURRENT arm64 RPI snapshot and make a bootable microsd card.
2. Make `rpi-firmware` and install
```
cd /usr/ports/sysutils/rpi-firmware
make install
cp -pr /usr/local/share/rpi-firmware/* /boot/efi/
```
3. Make latest `u-boot-rpi4` and install
```
cd /usr/ports/sysutils/u-boot-rpi4
make install
cp /usr/local/share/u-boot/u-boot-rpi4/u-boot.bin /boot/
```
4. Reboot. This boot will automatically adjust disk size during boot. It might take several minutes or hours depending on your hardware.