Hi Bill and guys, I need to build IOHIDFamily, so I download source code from Apple Opensource Website, and I don't know why I can not compile and build them using Xcode, here is my environment: 1. iMac with Intel CPU + Mac OS 10.7 + Xcode 4.1: build corresponding version of IOHIDFamily and xnu, both can not be built. 2. iMac with Intel CPU + Mac OS 10.6.8 + Xcode 3.2.6: build corresponding version of IOHIDFamily and xnu, both can not be built. Then I found Darwinbuild, here is my testing result, 1. Mac OS 10.7 + Xcode 4.1 + Darwinbuild: of course can not be built. 2. Mac OS 10.6.8 + Xcode 3.2.6 + Darwinbuild: still have some errors, both can not be built. 3. Mac OS 10.6(10A432) + Xcode 3.2 + Darwinbuild: Xnu is working!!! But IOHIDFamily still have some errors. I know debug is difficult if we have different environments & configurations, so I want to know what environment and configuration can work? For example: Mac OS 10.6(10A432) + Xcode 3.1.3 + Darwinbuild(rev. 9xx) Thanks you all! Ice