7 ms·

Zb extension is in both RVA22 and RVA23 profiles, meaning application cores (targeting consumer devices like smartphones) designed in the past few years almost

Zb extension is in both RVA22 and RVA23 profiles, meaning application cores (targeting consumer devices like smartphones) designed in the past few years almost certainly have shXadd instructions in order to be compatible with the mainstream software ecosystem

dmitrygr 2y ago
> meaning application cores (targeting consumer devices like smartphones where are they?
- camel-cdr 2y ago
  You are aware that hardware takes time to build, tapeout and productise? On the open-source front, I can right now download a RVA23 supporting RISC-V implementation, simulate the RTL and have it out perform my current Zen1 desktop per cycle in scalar code: https://news.ycombinator.com/item?id=41331786 https://news.ycombinator.com/item?id=41331786 (see the XiangShanV3 numbers)
  - fidotron 2y ago
    RISC-V has existed for over a decade and in that time no one has got close to building a competitive non microcontroller level CPU with it. How long is this supposed to take? How long until it is accepted that RISC-V looks like a semiconductor nerd snipe of epic proportion designed to divert energy away from anything that might actually work? If it was not designed for this it is definitely what it has achieved.
    - camel-cdr 2y ago
      The name RVA23 might give you a hint around which time the extensions required for high performance implementations to be viable were rougly standardized. The absolutely essential bitmanip and vector extensions were just ratified at the end of 2021 and the also quite important vector crypto just in 2023.
      - fidotron 2y ago
        So it took 10 years to ratify absolutely essential extensions? Somehow I suspect in 10 years there will be a new set of extensions promising to solve all your woes. Seriously, the way to do this is for someone to just go off and do what it takes to build a good CPU and for the ISA it uses to become the standard. Trying to do this the other way around is asking for trouble, unless sitting in committees for twenty years is actually the whole idea.
        snvzz 2y ago
        10 years from where? The base specifications in RISC-V were only ratified in 2019.
        fidotron 2y ago
        The first RISC-V chip was taped out in 2011. Source: https://riscv.org/about/#history https://riscv.org/about/#history
        snvzz 2y ago
        And the RISC paper[0] was published in 1980. Both are milestones that paved the way to RISC-V's base spec ratification in 2019. Incidentally, the Earth is estimated to be 4.54 billion years old. 0. https://dl.acm.org/doi/10.1145/641914.641917 https://dl.acm.org/doi/10.1145/641914.641917
        fidotron 2y ago
        So the ratification of a spec that will enable high performance implementation would be another 4.54 billion years after 2019? It's actually worse than that, because until it's done there's no guarantee it will ever get there.
        snvzz 2y ago
        Everything needed for high performance was ratified in 2021, just two years after the base spec. That's RVA22 and Vector 1.0. Low-end hardware implementing the spec already exists (Milk-V Jupiter). High end implementations (e.g. Ventana Veyron V2, designed for servers) will be deployed in 2025.

dmitrygr 2y ago

> meaning application cores (targeting consumer devices like smartphones where are they?

camel-cdr 2y ago
You are aware that hardware takes time to build, tapeout and productise? On the open-source front, I can right now download a RVA23 supporting RISC-V implementation, simulate the RTL and have it out perform my current Zen1 desktop per cycle in scalar code: https://news.ycombinator.com/item?id=41331786 https://news.ycombinator.com/item?id=41331786 (see the XiangShanV3 numbers)
- fidotron 2y ago
  RISC-V has existed for over a decade and in that time no one has got close to building a competitive non microcontroller level CPU with it. How long is this supposed to take? How long until it is accepted that RISC-V looks like a semiconductor nerd snipe of epic proportion designed to divert energy away from anything that might actually work? If it was not designed for this it is definitely what it has achieved.
  - camel-cdr 2y ago
    The name RVA23 might give you a hint around which time the extensions required for high performance implementations to be viable were rougly standardized. The absolutely essential bitmanip and vector extensions were just ratified at the end of 2021 and the also quite important vector crypto just in 2023.
    - fidotron 2y ago
      So it took 10 years to ratify absolutely essential extensions? Somehow I suspect in 10 years there will be a new set of extensions promising to solve all your woes. Seriously, the way to do this is for someone to just go off and do what it takes to build a good CPU and for the ISA it uses to become the standard. Trying to do this the other way around is asking for trouble, unless sitting in committees for twenty years is actually the whole idea.
      - snvzz 2y ago
        10 years from where? The base specifications in RISC-V were only ratified in 2019.
        fidotron 2y ago
        The first RISC-V chip was taped out in 2011. Source: https://riscv.org/about/#history https://riscv.org/about/#history
        snvzz 2y ago
        And the RISC paper[0] was published in 1980. Both are milestones that paved the way to RISC-V's base spec ratification in 2019. Incidentally, the Earth is estimated to be 4.54 billion years old. 0. https://dl.acm.org/doi/10.1145/641914.641917 https://dl.acm.org/doi/10.1145/641914.641917
        fidotron 2y ago
        So the ratification of a spec that will enable high performance implementation would be another 4.54 billion years after 2019? It's actually worse than that, because until it's done there's no guarantee it will ever get there.
        snvzz 2y ago
        Everything needed for high performance was ratified in 2021, just two years after the base spec. That's RVA22 and Vector 1.0. Low-end hardware implementing the spec already exists (Milk-V Jupiter). High end implementations (e.g. Ventana Veyron V2, designed for servers) will be deployed in 2025.