3 ms·
Yeah m68k is still around too and it has more than a decade on alpha. People use and maintain them and they have very little impact outside arch/ nowadays so t
by starspangled 2y ago
Yeah m68k is still around too and it has more than a decade on alpha.
People use and maintain them and they have very little impact outside arch/ nowadays so they're on the happy side of cost/benefit I guess.
- winocm 2y agoI guess the biggest difference is that Coldfire parts are still being produced (c.f: MCF52256CVN66). I'm not sure if Alphas are even being made anymore, even 15-20 years ago.
- Locutus_ 2y agoM68k has the advantage that it has a fairly typical memory model. Alpha's memory model has problems with providing atomic access to single bytes, which i'd imagine in a kernel is a bit annoying :-) And then there's just the social aspect, m68k was used in the Amiga/Atari/Mac/QL/x68k, so there is a whole generation of us m68k fans who are willing to keep it alive. Alpha has it's fans (me included!), but it's not exactly the same. So in a way it's no surprise it's slowly bitrotting away.
- winocm 2y agoAh, my favorite instructions, 'hw_ldl/l', 'hw_stl/c', 'ldl_l', 'stl_c' and their quadword siblings.
- starspangled 2y agoSince the C compiler can hide that, for core kernel code I think the more problematic thing was Alpha's memory consistency model where (data-)dependent loads accesses did not imply ordering, which is unusual and more burdensome to the programmer than any other ISA. That required this smp_read_barrier_depends() through the kernel, but actually in recent years that has basically been subsumed by other concurrent access primitives that all the core kernel must use, so I think alpha is no longer much of a problem outside arch/alpha