how windows finds correct drivers?

[mastermagrath]

Hi folks,

Can anyone describe how windows generally works in finding correct drivers for hardware. I've noticed over the years that when i insert e.g. USB based devices, windows as usual auto detects them adn attempts to find drivers for the device, which it may or may not find, this leads me to the following questions:

1. How does windows know if a driver is the correct one or incorrect one, i.e. can it read something from the device like a filename and look for it or something?
2. When windows suggests that 'a closer match was found' what makes a closer match? Is it by date or does the device supply a number of driver files to look for?

The reason i ask is so many times if i don't have the actual driver file that comes with a device i spend time going through a trial and error approach or relying on windows drivers. Is there some way a user can find out from the device what windows is looking for so the/she can go about finding it?

Cheers

 

[bcastner]

It can read a Hardware ID. To determine which driver to use it has a ranking system:

Windows XP Professional uses driver-ranking schemes to determine which driver to load when multiple drivers are available for a device. Drivers are ranked by whether they are signed and how closely their Plug and Play ID matches the device's Plug and Play ID. The Plug and Play ID of a driver or device consists of hardware IDs and compatible IDs. If the hardware ID of the driver exactly matches one of the hardware IDs of the device, there is a hardware match. If some other match occurs (for example, device hardware ID to driver compatible ID) there is a compatible match. Driver rank also depends upon whether the device information file (.inf file) for the device includes information specifically for installations in a Microsoft® Windows NT® environment. If multiple drivers for a device exist, the lowest ranking driver is installed. The following list summarizes the driver-ranking scheme for Windows XP Professional from lowest (best match) to highest rank:

1. Signed driver with a hardware match to the device.
2. Signed driver with a compatible match to the device.
3. Unsigned driver with a hardware match to the device (with Windows NT–targeted INF section).
4. Unsigned driver with a compatible match to the device (with Windows NT–targeted INF section).
5. Unsigned driver with a hardware match to the device (without Windows NT–targeted INF section).
6. Unsigned driver with a compatible match to the device (without Windows NT–targeted INF section).

 

[mastermagrath]

Thanks...

I guess then it doesn't really matter what a driver file is called, its actually the content. I originally wondered if i could find out what file the device needed (by name), then go through my disks and find it that way.....oh well!!