product(intx, AllocatePrefetchStyle, 1, \
          "0 = no prefetch, " \
          "1 = prefetch instructions for each allocation, " \
          "2 = use TLAB watermark to gate allocation prefetch, " \
          "3 = use BIS instruction on Sparc for allocation prefetch") \
          range(0, 3) \

but PPC port has the following:

src/cpu/ppc/vm/vm_version_ppc.cpp:
...
  if (AllocatePrefetchStyle == 4) {
    AllocatePrefetchStepSize = cache_line_size; // Need exact value.
    if (FLAG_IS_DEFAULT(AllocatePrefetchLines)) AllocatePrefetchLines = 12; // Use larger blocks by default.
    if (AllocatePrefetchDistance < 0) AllocatePrefetchDistance = 2*cache_line_size; // Default is not defined?
  } else {