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> The only argument I've ever seen for RISC-V that's vaguely logical is that there's no licensing to Arm involved, but since I can get M0/M3 devices for a dolla

> The only argument I've ever seen for RISC-V that's vaguely logical is that there's no licensing to Arm involved, but since I can get M0/M3 devices for a dollar or so with infinite tool and library support that's something that's totally irrelevant for most users. How expensive is it to license the instruction set so you can expand it?

lmz 2mo ago
Surely those expanding the instruction set do not fall into "most users"?
- jurgenburgen 2mo ago
  Everyone is paying for the license. Expanding was poorly phrased but the per-unit licensing cost might not be irrelevant. It might even make smaller batches cost-efficient for smaller manufacturers if they use an instruction set that doesn’t require a license.
pseudohadamard 2mo ago
Dunno, I'm still saving up for the billion-dollar fab I'll need before I can think about licensing an instruction set. As an aside, Espressif (or Xtensa if you want to split hairs) have been quietly doing a lot of what RISC-V is supposed to do for years now. I know they've also been fiddling with RV32's but all the real work is LX6/LX7. They're best-known for their use in ESP32s but they also crop up in an awful lot of industrial/commercial gear.
- just6979 2mo ago
  All the newest ESP32 variants for a bit now have been RISC-V. The last new LX7 was the ESP32-S3 (in fact, the S2 is the only other LX7), and LX6 is basically a legacy product that only lives on in the [non-variant] ESP32. The P4, the entire C and H series, and the new S31, are all RISC-V cores. Not to mention that RISC-V has even taken over for Espressif's classic ULP cores in all the same places (and even lives alongside it in the two LX7-based chips). They're well beyond "fiddling" with it.
- jurgenburgen 2mo ago
  My point is that if an ARM chip costs 1$ then how much is licensing? 0.1$? 0.5$? That’s money that doesn’t need to go to ARM if everyone is using unlicensed instruction sets.

lmz 2mo ago

Surely those expanding the instruction set do not fall into "most users"?

jurgenburgen 2mo ago
Everyone is paying for the license. Expanding was poorly phrased but the per-unit licensing cost might not be irrelevant. It might even make smaller batches cost-efficient for smaller manufacturers if they use an instruction set that doesn’t require a license.

pseudohadamard 2mo ago

Dunno, I'm still saving up for the billion-dollar fab I'll need before I can think about licensing an instruction set. As an aside, Espressif (or Xtensa if you want to split hairs) have been quietly doing a lot of what RISC-V is supposed to do for years now. I know they've also been fiddling with RV32's but all the real work is LX6/LX7. They're best-known for their use in ESP32s but they also crop up in an awful lot of industrial/commercial gear.

just6979 2mo ago
All the newest ESP32 variants for a bit now have been RISC-V. The last new LX7 was the ESP32-S3 (in fact, the S2 is the only other LX7), and LX6 is basically a legacy product that only lives on in the [non-variant] ESP32. The P4, the entire C and H series, and the new S31, are all RISC-V cores. Not to mention that RISC-V has even taken over for Espressif's classic ULP cores in all the same places (and even lives alongside it in the two LX7-based chips). They're well beyond "fiddling" with it.
jurgenburgen 2mo ago
My point is that if an ARM chip costs 1$ then how much is licensing? 0.1$? 0.5$? That’s money that doesn’t need to go to ARM if everyone is using unlicensed instruction sets.