nvmeadm namespace [-n] [namespace] [-v] [controller_name]
For example:
To list namespaces on all NVMe controllers:
nvmeadm namespace
SUNW-NVME-1 Namespace: 1
For details on namespace 1 on controller SUNW-NVME-1:
nvmeadm namespace -n 1 -v SUNW-NVME-1
SUNW-NVME-1 Namespace: 1 Block Size: 512 Capacity: 786146787328 Metadata Size: 0 Block Device Name: /dev/rdsk/c5t0d0s2 Status: online