GameCube support

[techflashYT]

Due to the inheritance of the original patches in use here (gc-linux -> DeltaResero -> neagix -> TheOtherOne -> here), this source tree still contains proper support for much of the hardware present in the Nintendo GameCube - not just the Wii.
However, this code has (supposedly) SEVERELY bitrotted over the years. Supposedly 4.19 doesn't even get into the bootwrapper properly, by some absurdity.
I'm hesitent to take this at face value, as I can't test this myself. I don't personally own a GameCube to test this on, and Dolphin doesn't seem to want to play ball, even with Rairii/Wack0's MMU patches that never got merged. So, this is all based off the words of Superbee, with his real GameCube and USB Gecko.

[techflashYT]

As of today, GameCube support works! Special thanks to Extrems for this commit in Swiss that allows real-mode executables such as the Linux kernel to boot properly!

See the attached boot log of wii-4.19 with a slightly modified gamecube_defconfig booting on Superbee's GameCube: bootlog.txt
A lot of work still needs to be done on it, but currently the framebuffer comes up, and it starts looking for a root device.
More to come soon.

[superbeelavaman]

Note: FBcon was also working, although with no rootfs and no (very expensive)
GameCube keyboard, I wasn't able to test much.

[techflashYT]

So, it boots:
(image of course by superbee again)

Currently systemd hangs, so this needed a modified version of mini_init to boot properly, but fixing systemd is being worked on.

Superbee has also said that he's getting a GameCube ASCII keyboard soon, so that can also be tested.
I still have some more optimization to do on the kernel, and will need to fix anything else that's discovered as broken, but as of currently, the supported features on GameCube:

• Controller support (the boot menu can now be controlled with it too)
• ARAM support (for swap)
• SDGecko support (primary storage method)
• Broadband Adapter (BBA) support (networking support)
• USB Gecko Support (serial console)
• (gcnfb) Video support

TODO:

• Kernel optimizations
• Ensure that the ASCII keyboard works
• Fix systemd
• Test audio
• Test overall system stability
• See if we can get paired singles working on the GameCube using the existing code from me and loganius
• Automated build tooling for GameCube
• Finishing polish
• Start publishing GameCube images on wii-linux.org

[techflashYT]

So there's been some new updates:

• Kernel has been optimized a bit
• ASCII keyboard is confirmed working

Most of the rest are still not done yet (the systemd crash is still particularly mysterious). Audio is very likely to work, though does still need to be tested. Haven't checked paired singles yet though they are quite likely to also work.