VM_KMEM_SIZE_SCALE specifies which fraction of the available physical
memory, after deduction of the kernel itself and other early statically
allocated memory, can be used for the kmem_map. The kmem_map provides
for all UMA/malloc allocations in KVM space.
Previously ARM was using a fixed kmem_map size of (12*1024*1024) = 12MB
without regard to effectively available memory. This is too small for
recent ARM SoC with more than 128MB of RAM.
For reference a description of others related kmem_map parameters:
VM_KMEM_SIZE default start size of kmem_map if SCALE is
not defined
VM_KMEM_SIZE_MIN hard floor on the kmem_map size
VM_KMEM_SIZE_MAX hard ceiling on the kmem_map size
VM_KMEM_SIZE_SCALE fraction of the available real memory to
be used for the kmem_map, limited by the
MIN and MAX parameters.
Tested by: ian
MFC after: 1 week
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