I am using the stretch-openmediavault-rock64-0.7.11-1075-armhf.img.xz with my rock64.
The latest image stretch-openmediavault-rock64-0.8.0rc10-1125-armhf.img.xz does not work.
some lines of the HDMI output:
... [23.217872] Rebooting in 90 seconds.. ... [9.627034] FAT-fs (mmcblk1p6): Volume was not properly unmounted. Some data may be corrupted. Please run fsck. [11.731829] rk-gmac-dwmac ff540000.ethernet eth0: Link is up -1Gbps/Full - flow control rx/tx [108.569222] systemd-journald: Failed to send WATCHDOG=1 notification message: Connection refused [192.784397] systemd-journald: Failed to send WATCHDOG=1 notification message: Transport Endpoint is not connected