4 ms·

Yep, it's not the full story. For ARM, the standard for that is SystemReady. UEFI is nice, but it realistically only defines the boot process. Once the OS has

by jchw 3y ago

Yep, it's not the full story. For ARM, the standard for that is SystemReady. UEFI is nice, but it realistically only defines the boot process. Once the OS has taken over there's a ton of other stuff that it has to do that will be defined by not the ISA of the CPU but by the platform, like enumerate devices or coordinate interrupts. For those two things in particular, it looks like a form of ACPI may be supported by some RISC-V platforms, and there's PLIC and APLIC for interrupts. Undoubtedly there are more things that I'm not thinking of, but I think that's a good start, as those are two things that were in fact NOT standard on many ARM SBCs.

mort96 3y ago
That seems correct to my understanding. So the question is, will RISC-C SBCs standardise on some set of technologies which makes it possible to make generic RV64 images which work across a host of machines? Or will those technologies stay niche, like SystemReady has in the ARM world?
- jchw 3y ago
  Good question; I hope they choose the path of standards early on, but it's not clear yet. I wonder if there's a genuine cost-cutting reason to not implement standards like ACPI. I believe SiFive was involved in the ACPI-on-RISC-V work, so that's probably a good sign. But honestly? I think we'll just have to wait and see.
- snvzz 3y ago
  Yes, and already done. For UEFI specifically, there's a relevant spec[0]. 0. https://github.com/riscv-non-isa/riscv-uefi/releases https://github.com/riscv-non-isa/riscv-uefi/releases
  - mort96 3y ago
    Oh, those technologies have already become non-niche? So if I survey the world of RISC-V SBCs, I will find that they can all pretty much just boot the same generic RV64 Linux distro images? No?
    - snvzz 3y ago
      AIUI Sifive's most recent board and VisionFive2 have working EDK2 UEFI. VF2's is early (boots Linux, but only from mmc. No NVMe, USB or display yet), but being worked on by StarFive themselves. In the future, with OS-A Platform spec, you can expect RISC-V computers to be no different than PCs from a user perspective. Under the hood, the platform is modern, and carries none of the legacy x86 PCs do. The scope of standardization is also broader: It's not just interrupts, timers or memory map, but also things like the interfaces for Watchdogs, GPIOs are being standardized.

by jchw 3y ago

mort96 3y ago

That seems correct to my understanding. So the question is, will RISC-C SBCs standardise on some set of technologies which makes it possible to make generic RV64 images which work across a host of machines? Or will those technologies stay niche, like SystemReady has in the ARM world?

jchw 3y ago
Good question; I hope they choose the path of standards early on, but it's not clear yet. I wonder if there's a genuine cost-cutting reason to not implement standards like ACPI. I believe SiFive was involved in the ACPI-on-RISC-V work, so that's probably a good sign. But honestly? I think we'll just have to wait and see.
snvzz 3y ago
Yes, and already done. For UEFI specifically, there's a relevant spec[0]. 0. https://github.com/riscv-non-isa/riscv-uefi/releases https://github.com/riscv-non-isa/riscv-uefi/releases
- mort96 3y ago
  Oh, those technologies have already become non-niche? So if I survey the world of RISC-V SBCs, I will find that they can all pretty much just boot the same generic RV64 Linux distro images? No?
  - snvzz 3y ago
    AIUI Sifive's most recent board and VisionFive2 have working EDK2 UEFI. VF2's is early (boots Linux, but only from mmc. No NVMe, USB or display yet), but being worked on by StarFive themselves. In the future, with OS-A Platform spec, you can expect RISC-V computers to be no different than PCs from a user perspective. Under the hood, the platform is modern, and carries none of the legacy x86 PCs do. The scope of standardization is also broader: It's not just interrupts, timers or memory map, but also things like the interfaces for Watchdogs, GPIOs are being standardized.