Getting the Driver Module's ID

Individual drivers can be unloaded by module id. To determine the module ID assigned to a driver, use modinfo(1M). Find the driver's name in the output. The first column of that entry is the driver's module ID.

# modinfoId	Loadaddr			Size		Info		Rev		Module Name

...

124	ff211000			1df4		101		1		xx (xx driver v1.0)

The number in the Info field is the major number chosen for the driver.