Notes:

The RELEASES is the latest stable version.
The pre-release is the latest development version.
For OpenMediaVault the armhf variant is preferred, as it offers the best compatibility.
Credentials (console/ssh, except OMV): rock64/rock64
Credentials (OMV): admin/openmediavault (Web), root/openmediavault (Console)
To enable SSH for OMV go to Web > SSH > Permit Root Login > Save > Apply
The U-boot introduces recovery button mode selection: ayufan-rock64/linux-u-boot@ea6efec

Upgrade:

sudo apt-get update -y
sudo apt-get install linux-rock64 -y

0.6.x

0.6.10: Add images to flash u-boot to SPI,
0.6.10: Fix rock64_write|erase_spi_flash.sh,
0.6.9: Fix USB booting from OTG,
0.6.9: Enable SPI support for Winbond in u-boot,
0.6.9: Introduce recovery button mode selection,
0.6.9: Enable control of rk805 leds from u-boot,
0.6.9: The rock64_write|erase_spi_flash.sh check MTD name,
0.6.8: Fix rock64_write|erase_spi_flash.sh scripts,
0.6.7: Fix u-boot booting (regression since 0.6.6),
0.6.6: Fix eMMC not working since 0.6.1,
0.6.6: U-boot supports USB2/3 booting,
0.6.6: Use Rockchip's u-boot tree,
0.6.5: Tag all dependent repositories,
0.6.4: Include mainline kernel in release,
0.6.3: Rebase mainline kernel and u-boot patches,
0.6.3: Fix libmali (make it work),
0.6.3: Fix small bug in rock64_write_spi_flash.sh,
0.6.2: Use RK DDR and SPL (allows SPI booting),
0.6.2: Release bionic instead of artful,
0.6.2: Include a bunch of updated drivers: xserver, libdrm, xf86-video-armsoc, etc.,
0.6.2: Include updated 4.4 kernel,
0.6.1: Make SPL/TPL actually to work,
0.6.1: Introduce rock64_write_spi_flash.sh and rock64_erase_spi_flash.sh,
0.6.0: Highly experimental,
0.6.0: Use SPL/TPL instead of Rockchip's loaders (supports flashing and booting from SPI),

Provide feedback