4 ms·

Then you have to worry about any "management" modes on the FPGA. https://www.cl.cam.ac.uk/~sps32/Silicon_scan_draft.pdf https://www.cl.cam.ac.uk/~sps32/Silicon

• jgtrosh 4y ago
  What's left, RISC-V? https://en.wikipedia.org/wiki/RISC-V https://en.wikipedia.org/wiki/RISC-V
  • pjmlp 4y ago
    Not really, because most deployments use UEFI alongside them. https://github.com/riscv-admin/riscv-uefi-edk2-docs https://github.com/riscv-admin/riscv-uefi-edk2-docs So if it isn't from door A, door B will do.
    • yjftsjthsd-h 4y ago
      How is UEFI like ME/PSP? I thought it was just for booting.
      • robotnikman 4y ago
        Its surprisingly more complex than that. You can run Doom in UEFI https://github.com/Cacodemon345/uefidoom https://github.com/Cacodemon345/uefidoom
        • yjftsjthsd-h 4y ago
          Okay, but that doesn't really bother me; running arbitrary payloads is the point of a bootloader. The only reason I would be worried by UEFI on RISC-V is if the UEFI firmware in question stays running in the background after the OS boots, and isn't properly inspectable. That might be the case - I have some vague notion of UEFI providing post-boot services, and for all that the EDK version is FOSS you could certainly make a closed version - but I'm not seeing any reason to panic just yet.
          • derefr 4y ago
            UEFI can provide post-boot services, but only in the same sense that a DOS-era BIOS did: by providing memory-mapped code that UEFI applications can call into, exokernel style. The UEFI framework isn't a hypervisor; it has no capacity to have ongoing execution threads "behind" the OS kernel. Rather, the OS kernel just receives a memory+PCIe map from UEFI at startup that contains some stuff UEFI left mapped; and it's up to the OS kernel whether to keep it mapped and make use of it; or just to unmap it. And no production OS kernel really uses any of the code that UEFI maps, or keeps any of said code mapped. It may keep the data-table pages (e.g. ACPI sections) mapped, for a while; but usually only long enough to copy said data into its own internal data structures. (Which is a shame, actually, as an OS kernel that did take advantage of UEFI services like UEFI applications do, would be able to do things that modern kernels currently mostly can't — like storing startup logs and crash dumps in motherboard NAND space reserved for that function, to provide on-device debugging through a separate UEFI crash-log-viewer app in case of startup disk failure, rather than needing to attach a separate serial debugger.)
            • LargoLasskhyfv 4y ago
              On X86/AMD64 there is also ACPI and SMM (System Management Mode), which overlap in parts. ACPI calls into code provided by whichever bootloader, running post-boot above to operating system, or behind its back, so to speak. It's complicated. [1] https://en.wikipedia.org/wiki/System_Management_Mode https://en.wikipedia.org/wiki/System_Management_Mode [2] https://en.wikipedia.org/wiki/Advanced_Configuration_and_Power_Interface https://en.wikipedia.org/wiki/Advanced_Configuration_and_Pow... Mostly for dynamic powermanagement and voltage regulation, monitoring temperatures, hotplugging, etc. That's just the way it is (now). I remember when this first made the rounds over a decade ago with some mainboards from CENSORED Apple supplier which were pretty usable, except when running under something else than Microsoft Windows. IIRC it wasn't malice, only implemented in a way which made this hard to interface with from Linux, or the likes. Of course undocumented. Later, but about the same timeframe the first so called open source/security 'zealots' damning ACPI in general for those reasons. It may be called differently on other platforms, but similar/equivalent mechanisms exist on almost everthing which is not in a museeum or landfill.
        • smoldesu 4y ago
          A malicious actor can do a lot of things in UEFI, but they can't decrypt my disk, they can't boot into my OS, and they can't mess with my userland environment. If Johnny Blackhat fancies a game of Doom over TTY on my desktop's UEFI environment, he can be my guest.
    • zekica 4y ago
      It is not just for booting. UEFI has Runtime Services that an OS can call.
  • classichasclass 4y ago
    POWER8 and POWER9 say hi.
    • LargoLasskhyfv 4y ago
      Money says bye.