Debugging UMDF drivers at boot using WinDbg

WINDBG
1

Hi,
I'm trying to debug my UMDF driver at boot time using WinDbg on an external machine.
I could not successfully attach the debugger to my driver.
These are the configurations I have made:

  1. On the target machine: bcdedit /debug on
    bcdedit 1394 channel:3 2. On the host: I chose Kernel Debug and defined it to be 1394 with channel 3
  2. I defined in the registry of the target: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\WUDF\Services{193a1820-d9ac-4997-8c55-be817523f6aa} - value 0x4. (I also tried with 0x8000004, just in case. Both failed. By the way, is this value in the documentation correct? It is written that the highest bit should be set, meaning that this value is incorrect. It should be 0x80000004 (one zero more)).
  3. I've defined in Event Filters - load module wudf* - enabled - handled.
    I did this because unlike debugging from the machine itself (normal UMDF debugging), I couldn't attach the debugger to the WUDFHost.exe process directly when I opened the debugger (this process does not exist on the host machine).
  4. I've added breakpoints:
    bu WUDFOsrUsbFx2!DllMain
    bu WUDFOsrUsbFx2!DllGetClassObject
    bu WUDFOsrUsbFx2!CMyDriver::OnDeviceAdd
    And a few breakpoints in my code itself.

The results were - the host did connect to the target, it did stop somewhere, but not in those breakpoints (even when I pressed "go" several times), and breakpoints I've set manually on the code were not highlighted. They appeared in the breakpoints window, but only with line numbers, no symbols (and it is the exact same code of the driver).
This is what appeared in the debugger's screen:

nt!DbgLoadImageSymbols+0x47:
81c55201 cc int 3
0: kd> g
nt!DbgLoadImageSymbols+0x47:
81c55201 cc int 3
0: kd> g
*** ERROR: Symbol file could not be found. Defaulted to export symbols for spsys.sys - Keyboard Hook Success
nt!DbgLoadImageSymbols+0x47:
81c55201 cc int 3
1: kd> g
nt!DbgLoadImageSymbols+0x47:
81c55201 cc int 3
1: kd> g
UMDF: Waiting 4 seconds for debugger to attach.
*** ERROR: Module load completed but symbols could not be loaded for secdrv.SYS
UMDF: No user-mode debugger found.
UMDF: Waiting 4 seconds for debugger to attach.
UMDF: No user-mode debugger found.

If anyone has any idea what I'm doing wrong, or what's missing, I would be more than happy to know.
Thanks,
Gadi