MIPS

[paulbarker]

So, I'm getting reasonably close to my first release. The thing thats really slowing me down at the moment is supporting 2 platforms:
- x86 (Bochs emulator)
- MIPS r2000 / r3000 (sys/161 emulator, google it)

I'm planning to drop the MIPS support since I'm finding it too difficult. There seems to be a lack of tutorials and documentation. I have the processor manual but that alone is never enough. Also, most of the MIPS code I'm using has licensing issues I need to sort out before I can release it.

Basically, I'm wondering if anyone else has developed an OS for the MIPS platform or has any docs for it (especially relating to threading and stack-switching). Once I've got the low-level stuff done (mostly re-written from scratch) its a simpler platform to program than x86, especially with the emulator having a system bus specially designed for education and ease of programming. I'd like to use it, but if the low-level stuff continues to prove so difficult I'll just drop it.

Thanks in advance,
Paul Barker

[Colonel Kernel]

Once I've got the low-level stuff done (mostly re-written from scratch) its a simpler platform to program than x86

Have you tried running any of your MIPS code on real hardware? IIRC, there are no pipeline interlocks on MIPS processors, meaning that you have to be aware of things like branch delay slots etc. when hand-writing MIPS assembly. Not that I've done it myself, but I've heard it's a major pain...

[paulbarker]

Simpler to program in C - mostly because of a really simple system bus accessible by memory-mapped I/O.

Its the assembly code stuff thats giving me the trouble (I've got interrupt handlers done but stack switching is just not going to happen). The emulator, of course, acts like real hardware with branch delay slots (but no cache).

GAS does cut out most of the trouble. It does so by re-ordering most of the instructions you write.