A happy medium might involve something like a BIOS that's just a vendor-provided library in an EEPROM but which somehow is guaranteed not to run anything in hid

A happy medium might involve something like a BIOS that's just a vendor-provided library in an EEPROM but which somehow is guaranteed not to run anything in hidden cores, BMCs, or via interrupts that the OS does not set up. Even then, it would be even better if that library were open source that the OS could carry its own artifacts of. Not because open source is great, but so the OS can truly be in control. The point u/bcantrill makes about the OS not getting DRAM error information gives me cold sweats! If the library is open source, then, yes, each boot loader and kernel will have to be built for the hardware it will boot on, at least until it gets far enough to get additional firmware/drivers from a boot image RAM disk or whatever.