There are two kernel images in the binaries/kernel directory.
- zImageBoot is the standard one, which will mount a root filesystem from flash.
- zImageInitrd uses an initial RAM disk for its root filesystem.
The default root password is 'rootme'. You'll be asked to change it at first login. I changed it to something else and then immediately back to 'rootme' so it remains the same as the Balloon 2 default root password.
To use ZMODEM to send files to the Balloon while it's running Linux, lrzsz needs to be installed. The Debian package file for this is conveniently in /root, so after logging in:
dpkg -i lrzsz_0.12.21-4.1_arm.deb
will do the necessary.
The root filesystem image doesn't have any kernel modules installed as standard, so you'll have to upload them to the Balloon. There's a file modules.tgz in the directory binaries/kernel. Upload this file and untar it into /lib/modules.
cd /lib/modules tar xzf [wherever]/modules.tgz
afterwards because it seemed like a good idea, but I don't know whether it's really required.