3 ms·

We probably want to encourage people to forget pre 1.0 vectors exists, to ease ecosystem fragmentation

• brucehoult 3y ago
  That's what the SiFive mafia have been trying to get people to do, for the three years since Nezha arrived with RVV 0.7.1, while they (still!) have zero RVV hardware available for the end user to buy. It's pure FUD. The x86 world somehow survives with MMX, SSE, SSE2, SSE3, SSE4, AVX, AVX2, AVX512. The Arm word has a few incompatible variants too, with VFP, a couple of variations of NEON, SVE, SVE2, MVE. In comparison, RVV draft 0.7.1 and ratified 1.0 are practically the same thing. With GCC 14 transparently compiling unmodified code using RVV C intrinsics to either 0.7.1 or 1.0 there is very little cost or reason not to support both. RVV 0.7.1 is available in the vast majority of RISC-V SBCs in the world today, from the $5 Milk-V Duo (1.0 GHz C906, 64 MB RAM, 256M & 512M available for a few bucks more), to the ~$30 Lichee RV [dock] and MangoPi MQ Pro, to the $120-$180 Lichee Pi 4A, to the $2500 64 core Milk-V Pioneer. With the sole exception of the CanMV-K230 (single core, 0.5 GB RAM), if a RISC-V board on sale today doesn't have RVV 0.7.1 then it doesn't have vectors at all.
  • kragen 3y ago
    i think the vast majority of risc-v sbcs in the world today don't support any v extension at all, yeah it's wonderful news that gcc is able to paper over the compatibility problems now
  • oconnor663 3y ago
    Deciding what to do about the version split seems tricky, but on the plus side, it's impressive that they implemented a lot of real hardware before they even froze the extension.
    • kragen 3y ago
      not really. standards consortia are notoriously sluggish and chinese hardware companies are famously agile