Btw, since today there is also another installation option that
involves only an SD card:
cd /tmp
wget http://d-i.debian.org/daily-images/armhf/daily/netboot/SD-card-images/firmware.MX6_Cubox-i.img.gz
wget http://d-i.debian.org/daily-images/armhf/daily/netboot/SD-card-images/partition.img.gz
zcat firmware.MX6_Cubox-i.img.gz partition.img.gz > /dev/sdZ
sync
with /dev/sdZ being the raw device for the SD card. This results
in an SD card that contains both u-boot and the netboot
installer, which loads everything else it needs over the network.
During the installation, you can simply repartition the SD card
and delete/overwrite any existing filesystem on it; i.e. you
simply replace the installer by the final installation. Once the
installer has started, it does not need anything from the SD card
anymore.
Regards,
Karsten