MFC r276439 (by alc):
Make the creation of the free lists dynamic, i.e., it is based on the
available physical memory at boot time. For amd64 systems with 64 GB
or more of physical memory, create free lists for managing pages with
physical addresses below 4 GB.

PR: 185727
Requested by: alc
Approved by: re (gjb)

MFC r270202:
Increase max number of physical segments on amd64 to 63.

MFC r257854 (discussed with alc@)

As of r257209, all architectures have defined
VM_KMEM_SIZE_SCALE. In other words, every architecture is now
auto-sizing the kmem arena. This revision changes kmeminit() so
that the definition of VM_KMEM_SIZE_SCALE becomes mandatory and
the definition of VM_KMEM_SIZE becomes optional.

Replace or eliminate all existing definitions of VM_KMEM_SIZE.
With auto-sizing enabled, VM_KMEM_SIZE effectively became an
alternate spelling for VM_KMEM_SIZE_MIN on most architectures.
Use VM_KMEM_SIZE_MIN for clarity.

MFC r276439 (by alc):
Make the creation of the free lists dynamic, i.e., it is based on the
available physical memory at boot time. For amd64 systems with 64 GB
or more of physical memory, create free lists for managing pages with
physical addresses below 4 GB.

PR: 185727
Requested by: alc
Approved by: re (gjb)

MFC r270202:
Increase max number of physical segments on amd64 to 63.

MFC r257854 (discussed with alc@)

As of r257209, all architectures have defined
VM_KMEM_SIZE_SCALE. In other words, every architecture is now
auto-sizing the kmem arena. This revision changes kmeminit() so
that the definition of VM_KMEM_SIZE_SCALE becomes mandatory and
the definition of VM_KMEM_SIZE becomes optional.

Replace or eliminate all existing definitions of VM_KMEM_SIZE.
With auto-sizing enabled, VM_KMEM_SIZE effectively became an
alternate spelling for VM_KMEM_SIZE_MIN on most architectures.
Use VM_KMEM_SIZE_MIN for clarity.