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defaulting VMCONFIG to /dev/null, and additionally ensuring VMCONFIG is not a character device before it is sourced. While here, be sure to exit if usage() is called. This should effectively be no-op, but the usage() output was discovered while investigating a larger issue. MFC after: 1 week X-MFC-with: r277458, r277536, r277606, r277609, r277836, r278118, r278119, r278206 Sponsored by: The FreeBSD Foundation