2 ms·

If the extra instructions also operate in extra state (e.g. extra registers) a kernel needs to know about their existence so it can correctly save and restore s

• my123 5y ago
  Not necessarily/really, the custom extensions still need to be enabled by the kernel before they can be used. As such, it isn’t actually an issue.
• ndesaulniers 5y ago
  You're confusing MSRs (which don't have to be saved/restored on context switch) with GPRs (which do).
  • saagarjha 5y ago
    Apple reserves certain MSRs that apply on a per-process basis, and thus must be applied on context switch.
  • ithkuil 5y ago
    Well if there is a truly undocumented extension, how do I know it doesn't come with it's own registers (e.g. like a floating point unit does)