World's most simple Windows driver - windows

Question

I have a slightly odd problem involving a MoGo mouse failing to charge when put in the cartridge slot of my Windows XP laptop. Long story, but one suggestion to fix it is to write a bespoke driver which only says "I'm functioning OK: don't turn the power off".
I'm figuring that this should be next to trivial, but my only experience of drivers is to download and install them through provided MSIs. I realised that I don't know:
What language they're written in.
What conventions they must follow.
How they are associated with their respective hardware.
Where they are located.
Or indeed, anything at all...
I also haven't found anything staggeringly helpful on the web - probably because they are aimed at a far higher level than I'm at.
Any insights would be welcome.

Answer 1

Microsoft provides a "Hello World" driver example in their documentation. This is an example of "World's most simple Windows driver". Unfortunately, it's 13 pages long and thus not a good fit for a StackOverflow answer.
The language they are written in is C++.
To get started, be sure you have Microsoft Visual Studio, the Windows
SDK, and the Windows Driver Kit (WDK) installed.
Their example contains one file called Driver.c that looks like this:
#include <ntddk.h>
#include <wdf.h>
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD KmdfHelloWorldEvtDeviceAdd;
NTSTATUS
DriverEntry(
_In_ PDRIVER_OBJECT DriverObject,
_In_ PUNICODE_STRING RegistryPath
)
{
// NTSTATUS variable to record success or failure
NTSTATUS status = STATUS_SUCCESS;
// Allocate the driver configuration object
WDF_DRIVER_CONFIG config;
// Print "Hello World" for DriverEntry
KdPrintEx(( DPFLTR_IHVDRIVER_ID, DPFLTR_INFO_LEVEL, "KmdfHelloWorld: DriverEntry\n" ));
// Initialize the driver configuration object to register the
// entry point for the EvtDeviceAdd callback, KmdfHelloWorldEvtDeviceAdd
WDF_DRIVER_CONFIG_INIT(&config,
KmdfHelloWorldEvtDeviceAdd
);
// Finally, create the driver object
status = WdfDriverCreate(DriverObject,
RegistryPath,
WDF_NO_OBJECT_ATTRIBUTES,
&config,
WDF_NO_HANDLE
);
return status;
}
NTSTATUS
KmdfHelloWorldEvtDeviceAdd(
_In_ WDFDRIVER Driver,
_Inout_ PWDFDEVICE_INIT DeviceInit
)
{
// We're not using the driver object,
// so we need to mark it as unreferenced
UNREFERENCED_PARAMETER(Driver);
NTSTATUS status;
// Allocate the device object
WDFDEVICE hDevice;
// Print "Hello World"
KdPrintEx(( DPFLTR_IHVDRIVER_ID, DPFLTR_INFO_LEVEL, "KmdfHelloWorld: KmdfHelloWorldEvtDeviceAdd\n" ));
// Create the device object
status = WdfDeviceCreate(&DeviceInit,
WDF_NO_OBJECT_ATTRIBUTES,
&hDevice
);
return status;
}
Full details found here:
https://learn.microsoft.com/en-us/windows-hardware/drivers/gettingstarted/writing-a-very-small-kmdf--driver