What:		/sys/bus/vmbus/devices/.../driver_override
Date:		August 2019
Contact:	Stephen Hemminger <sthemmin@microsoft.com>
Description:
		This file allows the driver for a device to be specified which
		will override standard static and dynamic ID matching.  When
		specified, only a driver with a name matching the value written
		to driver_override will have an opportunity to bind to the
		device.  The override is specified by writing a string to the
		driver_override file (echo uio_hv_generic > driver_override) and
		may be cleared with an empty string (echo > driver_override).
		This returns the device to standard matching rules binding.
		Writing to driver_override does not automatically unbind the
		device from its current driver or make any attempt to
		automatically load the specified driver.  If no driver with a
		matching name is currently loaded in the kernel, the device
		will not bind to any driver.  This also allows devices to
		opt-out of driver binding using a driver_override name such as
		"none".  Only a single driver may be specified in the override,
		there is no support for parsing delimiters.