If you have built a linux kernel before, you know it is based upon config in a .config-file. We have some ready-made config files in our repo, so our first step is often just to use one as a base. When we discussed building earlier, our first operation was simply stating that we want to use the gamecube_defconfig configuration. You find this file in arch/powerpc/configs/gamecube_defconfig.

The contents of this file is simply a set of switches on the form: MYCONFIG=y. (which means MYCONFIG turned on, as omission is by default no).

There are a few small changes I make to this file when building:

# turn serial communication over USB Gecko on
CONFIG_SERIAL_USBGECKO=y

# activate the possibility to use ext3 filesystem
CONFIG_EXT3_FS=y

# Make sure these are commented out. Causes some issues with more modern software like udevd. Might be okay for older software.
# CONFIG_SYSFS_DEPRECATED=y
# CONFIG_SYSFS_DEPRECATED_V2=y

What you may want to set here will depend on what you want to do.

One of the most important steps to configure during compilation is the kernel boot arguments. You might have to tweak these a bit as a you go, depending on your use case. Where to boot from etc. In arch/powerpc/boot/dts/gamecube.dts you find something along the lines of this (line 23 in my file):

chosen {
    bootargs = "root=/dev/gcnsda2 rw ip=on video=gcn-vifb:tv=auto force_keyboard_port=4";
    linux,stdout-path = &USBGECKO0;
};

Which tells the kernel to read the root file system from the second partition on the first memory card device. The most important bootargs to think abut here is:

• root= - Describes the root file system to boot from. By default, this is a network file system. Above it is changed to the second partition of the memory card in slot A.
• console= - The device to send the kernel log messages to.
• init= - The init application that will run once the system starts. Debian and others use SysVInit, SystemD etc. to start, and a explicit init-target is not needed. If you on the other hand just want to run a script or something, simple, then you can specify it here.
• video= - Describes how the image is rendered to the screen. gcn-vifb is the device to show it to, and tv describes the other settings (PAL vs NTSC and refresh rate). Some useful writeup of the options is available on the GameCube linux wiki.
• force_keyboardport= - Specifies which port we have our keyboard controller plugged into. I just use port 4 here, is that is where I plug the keyboard into. (for the uninitiated, the GameCube keyboard controller has two plugs; one for the regular gaming controller and one for the keyboard).
• ip=on - Do network setup at boot time.

Note! I have only tested the ASCII Keyboard Controller ASC-1901PO, but I guess it will work the same for the Action Replay keyboard.

This is probably the easiest way of interacting with the system. Just plug the keyboard in and use! You should make sure you have something to interact with. This can for example be done by setting up a getty (login process) on the console device using /etc/inittab:

0:2345:respawn:/sbin/getty 38400 console

Note: Why console? Why not tty1 or similar? Just because I couldn't find a way of doing so. I usually use my systems by using CTRL-ALT-Fx to navigate ttys, and couldn't find a way to access them interactively. Usually you just spam the inittabs with tty sessions and use them directly.

There are some drawbacks with approach:

• No CTRL-ALT-F1 keys to switch between TTYs. Seems like the layout hardcodes the F-keys to upper case letters. This is the main reason I overuse the console device instead of a tty device.
• Hard coded keyboard layout. The layout seems to be hardcoded to the layout printed on it.

The broadband adapter works pretty much out of the box. Just boot your system, and things will connect during initialization thanks to the ip=on boot argument. On boot the GameCube will also print its ip address, which is super convenient if you want to log into it. In Debian you can simply install openssh-server, and you can connect right away.

Having issues connecting to the internet? Only having local connection? Check a few things, like your /etc/resolv.conf and make sure it has valid values. Sometimes it is set to an ip that doesn't resolve correctly. I just set it to the google public dns:

nameserver 8.8.8.8

If you might also want to check your /etc/network/interfaces file to see that it has a valid setting for eth0:

auto eth0
iface eth0 inet dhcp

If you don't have it, you might want to try to install some software that handles internet connections like ifupdown in Debian. Other useful tools for debugging internet includes net-tools (for ifconfig) and iputils-ping (to be able to ping various addresses).

In the section about compiling above, I activated the USBGECKO serial option. This makes it possible for us to the the USB Gecko device for serial communication. To actually use it, we have to do two things:

• Create device node. Port A: mknod /dev/usbgecko0 c 4 64

  Port B: mknod /dev/usbgecko1 c 4 65

• Present something, like an application, to our gecko device. One example is by using inittab and specify it to use a getty process: t1:23:respawn:/sbin/getty 38400 usbgecko1

Using the above process, I can now plug my USB Gecko into slot B and my Macbook Air. On my Mac I see a device called /dev/tty.usbserial-GECKUSB0 when the USB Gecko is plugged in. This means I can for example use screen to log into my gamecube:

screen /dev/tty.usbserial-GECKUSB0

This will behave like any other shell, expect that you are communicating with your host over a GameCube Memory Card port! :)

Usage is also documented on the GC-Linux wiki page with some notes on root logins etc.

Like we saw above with USB Gecko, there are a few device nodes that can be useful to make (unless it happens automatically). Some can be useful for mounting file systems, while others are useful for logging in (like: USB Gecko). You can either make these as root on a running system, or during your debootstrap setup.

• Memory cards:

  # found in comments in drivers/block/gcn-sd.c
  # the device itself of memory card A
  mknod dev/gcnsda   b 61 0
  
  # the partitions in A
  # (max 7 partitions)
  mknod dev/gcnsda1  b 61 1
  mknod dev/gcnsda2  b 61 2
  mknod dev/gcnsda3  b 61 3
  mknod dev/gcnsda4  b 61 4
  mknod dev/gcnsda5  b 61 5
  mknod dev/gcnsda6  b 61 6
  mknod dev/gcnsda7  b 61 7
  
  
  # ---------
  
  # the device itself of memory card A
  mknod dev/gcnsdb   b 61 8
  
  # the partitions in A
  # (max 7 partitions)
  mknod dev/gcnsdb1  b 61 9
  mknod dev/gcnsdb2  b 61 10
  mknod dev/gcnsdb3  b 61 11
  mknod dev/gcnsdb4  b 61 12
  mknod dev/gcnsdb5  b 61 13
  mknod dev/gcnsdb6  b 61 14
  mknod dev/gcnsdb7  b 61 15
  

• Audio RAM:

  mknod dev/aram b 37 0
  

• USB Gecko

  # port A
  mknod /dev/usbgecko1 c 4 64
  
  # port B
  mknod /dev/usbgecko1 c 4 65
  

Sound seems to work out of the box, but requires some setup. The device gcn-ai seems to be detected just fine by Alsa when installed and running. Like all other linux distros set up from scratch, you will probably have some sound issues :)