ViGEm v1.10.0.0 faulty


I did a lot of research and testing the last couple days and have to share some results. In the latest release I assumed I fixed the bug where a deaf XBOX 360 headset was appearing on the system when – for some odd reason – the Up button on the D-Pad was pressed.

After an awful lot of searching and reading various threads I came across the IRP_MN_QUERY_DEVICE_RELATIONS request, which seemed to be linked to my particular issue. Since ViGEm uses the WDF I assumed that this request was handled differently than in WDM, the driver model that the ancestor ScpVBus uses. Well, I was partially right; the request does indeed get handled per default by the KMDF internally so i decided to just intercept and fail the BusRelations Request in my driver which at first glance seemed like it did the trick! Sadly due to all the euphoria I slapped together a new build and released it without further testing 🙄

But in reality I wasn’t intentionally fixing the issue with my code like I thought; I just forgot to read all of the documentation which stated that you also need to call IoSkipCurrentIrpStackLocation(Irp) after pre-processing the IRP or else! Well, from what I understand this ruined the IRPs stack in a way that the request got left in a pending state which looked fine after you create and use the emulated device but goes horribly wrong once you try to cleanly unplug it.

Ok, so I know what I have to revert but now we aren’t any closer to a proper solution like we were prior to this release 😕 Further investigation followed. In this case it was once again time for a Wireshark session and a real physical X360 pad. Simply pressing and holding the Up button on the D-Pad really isn’t a challenge and we receive the following expected INTERRUPT_IN traffic:

0000   1b 00 10 10 d5 b1 86 b8 ff ff 00 00 00 00 09 00 
0010   01 01 00 02 00 81 01 14 00 00 00 00 14 01 00 00 
0020   00 5e f5 24 03 20 fa 4f 08 00 00 00 00 00 00    

The last twenty bytes represent the transfer buffer content of one input HID report (well, it isn’t HID-compatible but you know what I mean) which looks just fine. Although this doesn’t differ in any way like my emulation layer does the native pad won’t announce it’s headphone jack while the virtual one does. I’m baffled. And out of ideas. For the moment.

I’ll be back on this! 😠