AMD features
  * Leaf 0x8000 0019  L1 TLB 1G Identifiers
  * Leaf 0x8000 001A  Performance Optimization Identifiers
  * Leaf 0x8000 001B  Instruction Based Sampling Identifiers

AMD bugs (?)
  * Figure out why leaf 0x8000001D L3 cache is half-size on e.g. Ryzen 5 1400
    + Most likely because the "max threads sharing" is half of the threads on
      the physical die (i.e. there are *two* L3 caches on one physical chip)
