Syncronization between User dll and Kernel Extention Dll

Hi ,
I want to use a mechanism wherein i can achieve syncronization between a user side dll and a kernel ext dll. Can i use semaphores? do we have acees to same semaphore object across user and kernel boundary?

Is there any way i can share a global variable across the boundaries.\, so that i can use the same for syncronization.
I want to avoid publish subscribe mechanism to avoid delays.

Regards,
Rishi