In general, the steps for exporting device or kernel memory are:
Set the D_DEVMAP flag in the cb_flag flag of the cb_ops(9S) structure.
Define a devmap(9E) driver entry point to export the mapping.
To set up user mappings to the device, use devmap_devmem_setup(9F). To set up user mappings to kernel memory, use devmap_umem_setup(9F).