4 ms·

The sheer number of RISC-V extensions and the resulting fragmentation is blowing my mind. No wonder they can't provide a single generic kernel.

tadfisher 2y ago
There are baseline profiles, like RV23A, that standardize a set of extensions for a class of hardware. Problem right now is that Qualcomm and Si-Five disagree on what extensions should be supported, and there is hardware shipping or in development with two different definitions.
- panick21_ 2y ago
  Literally everybody agrees except Qualcomm who want to basically no participate, come in on the side and make it quasi propitiatory.
  - GeorgeTirebiter 2y ago
    Couldn't Google (who after all does Android) simply declare that the 'official' RV64 is IMAFD (aka 'G') CJQTVPBHLNSUX ? (or whatever makes sense, given the android roadmap). https://en.wikichip.org/wiki/risc-v/standard_extensions https://en.wikichip.org/wiki/risc-v/standard_extensions And if they did this, this would prove why Android's parent company is called Alphabet!
    - panick21_ 2y ago
      There is a standard profile called 'RVA22' and 'RVA23' after that. If you watch the presentations from google on this, they will almost certainty target one of those two standards, very likely RVA23, specially if its now delayed. Android could also define its own profile, but there probably wont be a reason for why they would need to do this.
yau8edq12i 2y ago
It's really not that bad when you consider that RISC-V is built to be used in anything from a tiny mcu to a large server cpu. Compare with the set of extensions to x64, too.
panick21_ 2y ago
It hasn't actually resulted in that much fragmentation. Android will target the standard profile, they have already announced that. There are standard profiles that pretty much get used by everybody that is trying to make something that runs generic software. If you have some one of consumer electronic device that runs one specific software, you might not follow a profile, but even then most will follow a specific profile.

tadfisher 2y ago

There are baseline profiles, like RV23A, that standardize a set of extensions for a class of hardware. Problem right now is that Qualcomm and Si-Five disagree on what extensions should be supported, and there is hardware shipping or in development with two different definitions.

panick21_ 2y ago
Literally everybody agrees except Qualcomm who want to basically no participate, come in on the side and make it quasi propitiatory.
- GeorgeTirebiter 2y ago
  Couldn't Google (who after all does Android) simply declare that the 'official' RV64 is IMAFD (aka 'G') CJQTVPBHLNSUX ? (or whatever makes sense, given the android roadmap). https://en.wikichip.org/wiki/risc-v/standard_extensions https://en.wikichip.org/wiki/risc-v/standard_extensions And if they did this, this would prove why Android's parent company is called Alphabet!
  - panick21_ 2y ago
    There is a standard profile called 'RVA22' and 'RVA23' after that. If you watch the presentations from google on this, they will almost certainty target one of those two standards, very likely RVA23, specially if its now delayed. Android could also define its own profile, but there probably wont be a reason for why they would need to do this.

yau8edq12i 2y ago

It's really not that bad when you consider that RISC-V is built to be used in anything from a tiny mcu to a large server cpu. Compare with the set of extensions to x64, too.

panick21_ 2y ago

It hasn't actually resulted in that much fragmentation. Android will target the standard profile, they have already announced that. There are standard profiles that pretty much get used by everybody that is trying to make something that runs generic software. If you have some one of consumer electronic device that runs one specific software, you might not follow a profile, but even then most will follow a specific profile.