Some users trying to fix the BE issues of Mupen64Plus. I was able to compile Mupen64Plus on ubuntu MATE 16.04.5 LTS PowerPC today. Unfortunately it runs only with a black screen. I tested it with the rice and arachnoid video plugin. I posted my test in the Mupen64Plus PowerPC Big Endian issue thread. I hope, the developers can fix the issue. It would be great to have Mupen64Plus on the X5000 and X1000.
Those AmigaOne machines are badass. I remember reading about the X1000 and the XMOS co-processor before it was released. I have a bunch of vintage machines including numerous Amigas, but nothing with PowerPC processors. Very nice.
I never saw it with my own eyes, but I remember that people reported success in getting Mupen64Plus to run on the PS3 and the Wii in the 2008/9/10 era. We have always strived for cross-platform and CPU-independent support, but none of the current developers use any big-endian machines.
You're right that there is some kind of problem in the core. The debugging information that you posted above is very useful and shows some obvious differences in basic values which should match. I'll start digging through the code and see if I can find further tests to run, or problems which could cause the mismatch.
Yeah - it's worth noting that Wii64, the Nintendo 64 emulator for GameCube, Wii and Wii U, is an old fork of Mupen64. Mupen64plus and Wii64 diverged a long time ago, but it does mean that it was likely more compatible at some point in the past.
As an aside - it seems the bug we are discussing is in the CPU interpreter code. Wii64 actually has a custom MIPS dynarec developed for PowerPC, which actually makes games perform rather well (especially on the Wii U that has 1.24GHz PowerPC G3 derivative). I'm guessing it's a pipe dream to have that backported to mainline Mupen64plus, but it's an interesting challenge for those that are up to it.