Codeless kext loading problem

Question

I have created a codeless kext so that one of my USB devices does not get kidnapped by the AppleUSBUHCI driver. When I plug one in, it should be loading a different driver. It happens with both an FTDI and CSR device.

I put together my kext, and the info.plist looks a lot like the example here: http://www.projectosx.com/forum/index.php?showtopic=798 just with different VID/PID. I ran kextutil with -entZ and the only warning was that I had a different CFBundleId for my personality. I followed the instructions here, Reading and writing to USB (HID) interrupt endpoints on Mac, to get it loaded.

When I loaded the kext, it said it loaded successfully, but I cannot see it with kextstat, and when I plug in my device it still gets hijacked. When I try to do a kextunload, it says the kext was not loaded.

Any help would be appreciated.

Answer 1

From the Apple lists, I learned that codeless kexts will not show up with kextstat unless they link to an existing driver. My personality that linked to the IOKit bundle would only show after load if it had stub code.

For my device, I found an existing driver for similar devices, and first injected a personality into that driver. I was able to verify it loaded when I plugged in my device, and I could open my device. I restored that driver to the original state. Then I created a codeless kext with the personality I had injected in to the existing driver. That driver then got loaded when I plugged in my device and I was then able to communicate with my device.

The solution to my original problem was the CFBundleIdentifier for my original codeless kext and the bcdDevice. From http://lists.apple.com/archives/usb/2009/Aug/msg00050.html, I got hints about different types of codeless kexts and realized I needed to use the CFBundleIdentifier for the existing driver.