When I add the .ko file to
/lib/module/(uname -r)/kernel/drivers/net/wireless/
the driver will be used to drive my USB adapter when I start the computer, at least when I execute 'depmod' after copying the file to a folder under .../kernel/drivers/net/wireless/
or .../kernel/net/wireless/
When I copy the driver to a folder under .../build
the driver which is also a module isn't used to drive my USB adapter when I start the computer. Also when placed under build, 'modprobe' can't find the module after executing 'depmod'.
This actually tells me that .../build is never a good choice for placing a driver.