Likely impossible unless you somehow come up with something vastly better (unlikely).
None of these things are remotely bad enough to make the downsides of using another ISA palatable.
Likely impossible unless you somehow come up with something vastly better (unlikely).
None of these things are remotely bad enough to make the downsides of using another ISA palatable.
How about EPIC-esque packet-based instructions?
64-bit instructions with 4 bits indicating instruction formats (60-bit, two 40+20-bit variants, 30+30-bit, 20+20+20-bit, three 30+15+15-bit variants, and 15+15+15+15-bit). Have each larger instruction type be a strict superset of the smaller instructions, but with larger immediates, more registers, and maybe additional instruction formats (eg, for SIMD).
Something like that would be even easier to decode (converting short instructions to long is simply a bit of wiring). Instruction density should increase due to 20-bit instruction type. Having properly-aligned instructions would help with fetching performance. Larger instructions means you can jump 4x further with the same immediate and 16-bit offsets. No need to have some of the V extension workarounds (from not wanting to add 48-bit instructions).
Anther ISA like ARM? It seems pretty palatable to just about everyone not academic.
The ARM ISAs are not free to implement. ARM holds patents relevant to the ISA.
Until the patents expire, which many have already.
The aarch64 stuff still has some time, particularly if you want stuff like virtualization.
You're vastly underestimating the amount of work that has gone into RISC-V that would need to be redone. It's not just a spec. There's an absolute mountain of software and hardware supporting it.
Sure. But … so was Linux, or Firefox, or GNOME or KDE, etc.
Even RISC-V itself was adopted by volunteers and supported by toolchains, and then kernels, and applications.
The amount of work is less a problem than the motivation. And motivation really just depends on recognizing that the status quo sucks, but is fixable.
And yet, new ISAs arise fairly regularly, for various reasons. RISC-V itself succeeded largely because it is gratis, I think.