were not present when dev_mkdb(8) was run.
First the dev_mkdb(8) database is searched, this caters for non-DEVFS
cases where people have renamed a device.
If that fails we ask the kernel using sysctl kern.devname if the device
driver has put a name in the dev_t. This covers DEVFS cloned devices.
If that also fails we format a string which isn't entirely useless.