To flash U-Boot:

- Enter maskrom mode (hold down maskrom button during powerup or use the maskrom jumper)
- connect the usb c port of the board to your host 
- rkdeveloptool db rk3588_spl_loader_v1.08.111.bin
- rkdeveloptool wl 64 u-boot-rockchip.bin

Some notes:

- The boot image is an EFI system partition, U-Boot implements EFI
- You can flash it to eMMC, SD card or USB disks (booting from USB requires running usb start in U-Boot shell manually)
- Includes mesa 25.1.0, which isn't in Alpine yet
- Kernel and device packages aren't packaged in postmarketOS yet, so future upgrades are impossible
- This is only intended for testing
- The image includes systemd + GNOME, you can switch to OpenRC or a difference DE by (un)installing the appropriate packages
- Quirks:
    - Rebooting is broken and will not power up the board after shutdown, you will need to manually power cycle it
    - MIPI CSI / DSI and PCIe are not implemented yet (amongst some other things, see https://gitlab.collabora.com/hardware-enablement/rockchip-3588/notes-for-rockchip-3588/-/blob/main/mainline-status.md?ref_type=heads)