SPARC is owned by SPARC International, a non-profit. Its specs and everything are open:

http://sparc.org/technical-documents/

One embedded implementation with a ton of supporting I.P. is GPL'd, FPGA-proven, ASIC-proven, and rad-hard in some verisons:

http://www.gaisler.com/index.php/downloads/leongrlib?task=vi...

And then there's Oracle, their badass chips, and their evil ass lawyers. We can stay away from all that. SPARC is better and safer than Oracle but very importantly SPARC != Oracle.

Is there are repository for this? Or do they still do the cathedral model?

I'm pretty sure it's the catheral model. I'm not even sure that they're doing open-source with Leon4 onward as pretty much nothing happened with GPL'd Leon3 and GRLIB. Comp Sci people and companies doing rad-hard, space apps are still getting and building on it.

Best way to deal with them is to straight-up license their tech for a Pi- or router-style board. Then fab, assemble, and sell that joker. That gets the ecosystem going. CompSci people doing CPU's or RISC-V work can keep building reusable components both can use. Then we just pay for the integrations.

I've done school-size CPUs with http://www.clash-lang.org/ --- it would be fun to convert someone's "real-world" design into Haskell with it. 'Twould really show off that order of magnitude code size reduction :).

I suppose cathedral vs bazaar doesn't affect that at all, but experience has ingrained in me "source tarball ==> won't easily build" biases.