amount of physical memory, divide it by 4, and then allow machine
dependent code to place upper and lower bounds on the size. Export
the computed value to userspace via the new "vm.nkmempages" sysctl.
NKMEMCLUSTERS is now deprecated and will generate an error if you
attempt to use it. The new option, should you choose to use it,
is called NKMEMPAGES, and two new options NKMEMPAGES_MIN and
NKMEMPAGES_MAX allow the user to configure the bounds in the kernel
config file.