Well, I spent several days trying to boot Archlinux ARM on H96 TV-Box and got so far. So, lemme explain investigation results and hope if anyone will help me to finish the work.
The idea was to connect to the Linux serial console via UART, so, playing for several minutes with a multimeter I figured out the UART port uses 3.3V voltage and after a barbaric way of soldering and a couple of attempts, it spills the RT/TX layout (see the h96-top.jpg attachment).
But, after connecting via (minicom -b1500000 -D/dev/ttyUSB0 -C log), what I was seeing was only a sequence of "cryptographic" characters. Changing baud-rate and pulling signal lines using resistors brought nothing useful. After minutes of research and changing USB-UART converter, it showed me the boot log and login prompt (see the 0-android.boot.log.gz attachment). Well, it happened the previous USB-UART didn't manage to work at 1500000 baud rate.
The next steps were:
- mounting an external SD card
- dumping all the internal /dev/block/mmcblk2 partitions in order to unpack them and find something useful (like DTB) in there.