I got my MK802 working like this:
1. Download and install a pre-built Ubuntu image (google for it); that got me a working system, so I could be sure that the bootloader, kernel etc were correctly configured.
2. Backup the /lib/modules diectory from the working image
3. Wipe the linux partition, and then install the Arch runtime into it
(
http://us.mirror.archlinuxarm.org/os/Ar ... est.tar.gz)
I also installed the netcfg package.
4. Edit the following files to ensure that I could log into the system after it had booted:
/etc/shadow (to set a root password: I just copied this from another machine)
/etc/rc.conf (to load the "net-profiles" daemon)
/etc/conf.d/netcfg (to load a profile named "wlan0")
/etc/network.d/wlan0 (copy /etc/network.d/examples/wireless-wpa and fill in the ESSID and key)
5. Copy back the contents of the Ubuntu /lib/modules directory into /usr/lib/modules
Then the MK802 booted into Arch, using the ubuntu kernel,and I could log in using ssh.
If it doesn't seem to be working, mount the SD card on another machine and have a look at /var/log/boot and /var/log/everything.log to see what is wrong.
The next stage will be to replace the Ubuntu kernel and bootloader with the Arch ones, to see whether I can get them to work.