Driver Backup using setupapi

I'm stuck. To cut long story sho开发者_如何学Gort, the task is to enumerate all driver files for backup. For some drivers like display adapter driver, I use

SetupScanFileQueue(queueHandle,
             SPQ_SCAN_USE_CALLBACKEX,NULL,
             DumpDeviceDriversCallback,&count,&scanResult)

from setupapi and that's working fine as in DumpDeviceDriversCallback I can get the Source of the device driver file and then copy it to backup location one by one.

However, the same function ignore the callback for system drivers. For example for "Direct memory access controller" I can not get the list of files. Funny thing, but windows device manager also can not find any files for some of the system devices.

Some special software like DriverMax and DoubleDriver actually CAN backup those driver. So, this is the problem that may be solved.

Anyone can explain me what is going on here?

There are lots of devices that are installed using what's called a "No Driver" INF. These INFs provide enough information such that Device Manager will have some info to show for the device (thus avoiding them appear in the "unknown devices" category) but don't actually install any drivers.

These devices do not need drivers because they are managed by either the O/S itself, the BIOS, or both. Usually these devices are all "installed" using machine.inf, which has a giant list of known no driver devices.

As for any software that claims to back the drivers for these devices up, either they're just copying the INF or they're full of it because there's nothing but the INF to back up.

-scott