Hi Guys,
I have written a KMDF driver which needs at least three MSIx vectors and can handle up to Max of 32 MSIx vectors. If the driver gets anything less than three vectors, it cannot operate and returns error from “PrepareHardware” Callback. I have tested the driver under QEMU and it works great.
I tried the driver with actual hardware (FPGA) on another machine and for some reason the “PrepareHardware” always gets called with 1 interrupt resource and with only one MSIx message.
I looked at the registry to make sure that the INF file add registry directive is actually creating the MSIx registry entries. I could see that the registry entries are created under
Check the Full set of Capability structures, also.
Also, I like to check the requested resources by DbgPrint’ing the resource list(s) at the pre Prepare Hardware callbacks (like Query Resource RequirementsQuery Resource Requirements.
Maybe one of those will help you understand what’s going on.
Be certain you’re requesting MSI-X resources, and not MSI resources. You should be able to get 32 MSI-X resources, but you’re very unlikely to get 32 MSI resources.
Thanks for the help @“Peter_Viscarola_(OSR)” and everyone else , I have been a long long time poster on this list, though disappeared for a few years in between, and I always believed the community created by OSR is nothing short of a blessing for all the windows kernel developers. Its amazing what you guys have done and achieved.
-Aj