Leon (SPARC V8 ISA) is a free, open source implementation, and is a radiation hardened processor.
Why is that not enough?
[1] https://www2.eecs.berkeley.edu/Pubs/TechRpts/2014/EECS-2014-...
How ironic that the paper thinks that reigster windows, one of the most powerful features of the UltraSPARC processor, which gives the processor 256 virtual registers, is including too much. Wow. Are these guys unfamiliar with the UltraSPARC, or what?!?
Also they imply that delayed branch in MIPS and SPARC is somehow bad, but they don't write that for every branch instruction an UltraSPARC doesn't take, one gets a free instruction execution slot inside of the same clock cycle... what's that all about?
The paper even mentions that SPARC V8 has been turned into a IEEE standard.
This whole paper reeks of the "not invented here", and "we just want to build our own processor and we think everyone should use ours, it's the best!"
The only practical plus I see in OpenRISC's favor is 128-bit addressing.
The only implication of non-free that I could find in the paper mentioning SPARC is that SPARC V9 is proprietary, but proprietary does not mean that it's not open, just that someone owns the implementation.
My conclusion is: "we just wanted to design our own processor no-matter-what, and you should use ours!"
Umm, no, I won't do that, because any new processor needs assembler coders with several decades of experience (I code in assembler, so I know what's involved), and they have to be capable of implementing a compiler which can generate code which can take advantage of the processor. Case in point is Itanium, a very fast processor which left out most of the hardware for an assumption that the compiler will be good enough to generate code which will take advantage of it. That never really materialized and Itanium has gone down in history of computing as "Itanic".
UltraSPARC is a very powerful processor, and when utilized correctly, it is a very fast processor, designed to be fast and designed to be powerful and extensible (SPARC stands for Scalable Processor ARChitecture). The code to synthesize and modify the existing design is free. Not only is it free, it was one of the first, if not the first processor designs ever to be open sourced and made freeware. It has Sun Studio which has evolved enough to take advantage of the processor features, so one can just hit the ground running with the design. 128-bit addressing of OpenRISC and not having to pay a one time $50 USD licensing fee is, in my view, not enough of an incentive to start from scratch trying to fix something (UltraSPARC RISC) which does not need fixing.
If some group with the resources and skills wanted to they could take UltraSPARC T1/T2 code, update the CPU with modern techniques for the design, and then ship it off to a fab company to have it built and sold and Sun's patents wouldn't be infringed upon so long as they make it Free software?
I don't know what you would change but from my understanding CPU design has had some major changes since this CPU so I'm assuming there are tricks or things that could be done to speed the thing up but then again I don't know.
I wish someone capable did this. Having a Free CPU would be great. It would be especially great for this sort of RISC CPU to create a new low-power high-performance that was promised.
Remember...
RISC architecture is gonna change everything - Hackers (1995)