Windows OS Driver Development Notes

What is driver

a driver is a software component that lets the operating system and a device communicate with each other

What is filter driver? And what is their use case?

Drivers that perform auxiliary processing are called filter drivers

What is function driver and what is their use case?

The one driver in the stack that communicates directly with the device is called the function driver

What are software drivers and what is their purposes?

some drivers are not associated with any hardware device at all. It is not associated with a hardware device

What is I/O request packets (IRP)? What does it carry? Who sends and receive it?

Most of the requests that are sent to device drivers are packaged in I/O request packets (IRPs). An operating system component or a driver sends an IRP to a driver by calling IoCallDriver, which has two parameters: a pointer to a DEVICE_OBJECT and a pointer to an IRP.

What is device object? What is driver object? In what context they are used?

A device object represents a logical, virtual, or physical device for which a driver handles I/O requests.

driver object represents the image of a loaded kernel-mode driver.

What are the key steps to develop a driver and which APIs are most important?

DriverEntry - entry point for any driver like main in any app. This is not an API.

Here, we initialize driver-wide structures and resources. Mapping driver configuration to our call back funtion. Inside callback function we call WdfDeviceCreate to create device object.

WdfDriverCreate - Create driver object. It uses driver configuration object.