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DriverEntry is the first routine called after a driver is loaded, and is responsible for initializing the driver.
NTSTATUS
DriverEntry(
IN PDRIVER_OBJECT DriverObject,
IN PUNICODE_STRING RegistryPath
);
If the routine succeeds, it must return STATUS_SUCCESS. Otherwise, it must return one of the error status values defined in ntstatus.h.
The DriverObject parameter supplies the DriverEntry routine with a pointer to the driver's driver object, which is allocated by the I/O Manager. The DriverEntry routine must fill in the driver object with entry points for the driver's standard routines.
The DriverObject pointer gives the driver access to DriverObject->HardwareDatabase, which points to a counted Unicode string that specifies a path to the registry's \Registry\Machine\Hardware tree.
The registry path string pointed to by RegistryPath is of the form \Registry\Machine\System\CurrentControlSet\Services\DriverName. A driver can use this path to store driver-specific information; see Driver Information in the Registry. The DriverEntry routine should save a copy of the Unicode string, not the pointer, since the I/O Manager frees the RegistryPath buffer after DriverEntry returns.
A driver's DriverEntry routine executes in a system thread context at IRQL = PASSIVE_LEVEL.
For more information about implementing a DriverEntry routine, see Writing a DriverEntry Routine.
While it is possible to name this routine something other than DriverEntry, doing so is not recommended. The DDK-supplied build tools automatically inform the linker that the driver's entry point is called DriverEntry, so giving the routine another name requires you to modify the build tools. For more information about build tools, see Building Drivers.