Fix & document the GE module

[artart78]

This module was long in a stall state, as the reverse engineered code was finished, but not much documented, and buggy as rendering stopped at some point during boot.

The issue was actually quite basic: some enum's taking the space of an u32 instead of an u8 introduced an incompatibility between sceGeListUpdateStallAddr, written in assembly, and the rest of the code. (It also made the size wrong, which could introduce further bugs).

During this work, a few nice discovers were made:

• the old/codename of the GE is "Aw" (although it's unknown what these letters stand for);
• there exists a "L2 cache" (name found from NIDs) on the newer (04g+) models, which seems to be another controller to which commands are sent, although nothing more is known about it
• and, of course, various details about how the GE works for the "end user" (mostly kernel-side).

Now pretty much 100% of the GE is understood (if we don't care too much about the fussy details about "why must this be synchronized only in that case?"). Yay!

The code also could give access to GE debugging functions, which are normally not accessible on retail PSPs.

PS: I didn't do it yet, so I'll try to test the last version with the uOFW installer before this is merged.

[Felix-Dev]

@artart78 Our gh-actions script has just been updated in PR https://github.com/uofw/uofw/commit/2410eb9a606fe274b4f47b5aad0c01de6c009bd6 so you can merge master into this branch to get the build pipeline results.

[artart78]

FYI, I tested the latest GE module yesterday and it works perfectly in the VSH and in a game!

I'm not a big fan of letting that pull request stay here forever, so if someone wants to review it, let me know, otherwise I'll merge it in a week or so.

[devnoname120]

@artart78 I don't have extensive knowledge about GE. But if you want I can do a cursory review anyway.

[artart78]

@devnoname120 sorry I forgot to answer your comment. I'll merge this anyway as it has been waiting for a while but feel free to review the code anytime if you want ;)

[devnoname120]

@artart78 No worries! Life got a bit busier nowadays so I'll let an hypothetical future traveler review it 😉