Driver to driver communcation

NTDEV
1

Dear,

My USB mouse exposes a keyboard and a mouse interface. I’ve created two filter driver for each of these interfaces and I’d like to be able to have them communicating, if possible by sharing a common buffer.

I’m trying to follow this guide : http://www.osronline.com/article.cfm?id=177

I have a few questions :

  • Is this guide still valid ? is it the WDF way to do this ?
  • What does “context block” means ? Can you point me to the function that will help me create one ?
  • As I need a PDEVICE_OBJECT to use IoCallDriver, I’ll need (from the mouse filter driver point of view) to get the one corresponding to the keyboard interface. I tried using IoGetDeviceObjectPointer but I need to determine the ObjectName…
    So I tried using IoGetDeviceInterfaces to get the names of the device interfaces corresponding to the keyboard and I end up listing all the keyboard interfaces available on my computer. How can I narrow down this list to the keyboard interfaces of my physical device only ?

Hope someone will be able to help me sort this out.

Best regards,

2

I tried using :

status = IoGetDeviceInterfaces((GUID*)&GUID_DEVINTERFACE_KEYBOARD,
WdfDeviceWdmGetPhysicalDevice(device),
0,
&symbolicLinkList);

But I end up with no results at all.

3

You don’t get to your own physical device object on the stack where you find the device interface for another stack. are the 2 filters in the same driver object/.sys file? if so, you can judiciously use globals to keep track of state and then you don’t have to send io requests to each filter. opening a handle to a filter in the input stacks is difficult; mouclass and kbdclass will not let your io requests go through to the filter below them.

d

4

The two filters are not in the same .sys file. But if it’s possible I’d like to do that.
I definitely need more precision about that if that could be done, and I’d like to understand what’s the difference between my situation and the one related in the article ?

5

When I try referencing the same .sys in both .INF I end up with this error :

Windows cannot load the device driver for this hardware because a previous instance of the device driver is still in memory. (Code 38)

Any clue ?

6

I think the problem was the service installation in the INF file.
I can use globals now, and I think this will solve my problem.

Thank you !