Architectural Comparisons

This table compares important factors for a decision in which ISA to use and support

Open NO (1) NO (2) WIP (3) Yes
Libre-friendly NO (1) unknown Yes Yes
Trademarked Yes Yes Yes No
Extensible NO (4) unknown Potentially (5) Yes
gcc Yes Yes Yes Yes
llvm Yes Yes Yes Yes
llvm upstream Yes Yes Yes No
distros (debian) Yes Yes Yes No
distros (ubuntu) No No Yes No
distros (fedora) Yes Yes Yes No
buildroot Yes Yes Yes Yes
linux kernel Yes Yes Yes Yes
64-bit linux Yes Yes Yes No
virtualizable Yes unknown Yes No (6)
64-bit asics many many many none
sw community size large medium very large tiny (7)
little-endian asics Yes Yes Yes No
Java (OpenJDK) no JIT unknown Yes No
Java (Android) No? Yes No No
V8 node.js/chromium no JIT Yes Yes No
PyPy No No Yes No
Mono (.net) No? 32-bit Yes No
Spidermonkey (Firefox JS) no JIT Yes (JIT Unsupported) no JIT No
  • (1) too numerous reasons to count, for well over 4 years.
  • (2) efforts to be "open" have stalled, website non-functional
  • (3) OpenPower Foundation making a huge effort, really appreciated
  • (4) repeated in-good-faith requests for participation and inclusion in extending RISC-V have met with stone-cold silence for over 18 months, in direct violation of Trademark Law's clear-cut responsibilities.
  • (5) provisionally and in principle: yes. however as of 2019jan21 this is yet to be tested and an agreement reached.
  • (6) no mentions of virtualization found in spec
  • (7) dozens to hundreds of people, several companies