TBH I still don't really get how it's different from MIPS. As far as I can tell... Loongson seems to be really just MIPS, while LoongArch is MIPS with some extra instructions.
Wait, this is a modern-ish ISA with a software-managed TLB, I didn’t realize that! The manual seems a bit unhappy about that part though:
> In the current version of this architecture specification, TLB refill and consistent maintenance between TLB and page tables are still [sic] all led by software.
(purely on vibes) loongson feels to me like an intermediate step/backup strategy rather than a longterm target (though they'll probably power govt equipment for decades of legacy either way :p)
TBH I still don't really get how it's different from MIPS. As far as I can tell... Loongson seems to be really just MIPS, while LoongArch is MIPS with some extra instructions.
They did get rid of the delay slots and some other MIPS oddities
LoongArch is, on a first approximation, an almost RISC-V user space instruction set together with MIPS-like privileged instructions and registers.
Wait, this is a modern-ish ISA with a software-managed TLB, I didn’t realize that! The manual seems a bit unhappy about that part though:
> In the current version of this architecture specification, TLB refill and consistent maintenance between TLB and page tables are still [sic] all led by software.
https://loongson.github.io/LoongArch-Documentation/LoongArch...
I think they have already added hardware page table walks.
https://lwn.net/Articles/932048/
But legally distinct! I guess calling it Ｍ○ＰＳ was not enough for plausible deniability.
ISAs shouldn't be patentable in the first place.
(purely on vibes) loongson feels to me like an intermediate step/backup strategy rather than a longterm target (though they'll probably power govt equipment for decades of legacy either way :p)