XCode 4.5 builds invalid 32-bit kext binaries

Number:rdar://12353507 Date Originated:22-Sep-2012 09:56 PM
Status:Open Resolved:
Product:Developer Tools Product Version:4.5
Classification:Serious Bug Reproducible:Always
i386 kernel extension binaries built by XCode 4.5 contain the loader commands LC_DATA_IN_CODE and LC_FUNCTION_STARTS. Neither of these is supported by kxld in kernels older than OSX 10.8. The kexts built this way are therefore rejected by OSX Lion, Snow Leopard, etc.

Steps to Reproduce:
- Open XCode
- File -> New -> Project…
- Choose "I/O Kit Driver"
- Complete the assistant
- Set the target's deployment target to 10.7 or earlier
- Set architectures to Intel 32/64-bit.
- Build the 32-bit version (or a fat 32+64-bit binary)
- Run the terminal command:
otool -lV -arch i386 /path/to/kext/Contents/MacOS/binary_name

Expected Results:
No unsupported commands should be listed.

Actual Results:
Near the end, LC_DATA_IN_CODE and LC_FUNCTION_STARTS commands are present.

If you open and build the same project using XCode 4.4.1 or earlier, the produced kexts are fine.

- It does not matter whether XCode 4.5 is running on OS X 10.7 or 10.8, the produced kexts are always bad.
- The 64-bit versions are not affected and do not contain the relevant commands.
- An affected "fat" kext can be loaded on a 64-bit system, but it seems to interfere with kernel prelinking.
- Relevant thread in the darwin-kernel mailing list: http://lists.apple.com/archives/darwin-kernel/2012/Sep/msg00025.html


Fixed as for me with 4.6 (4H127).

Update from Apple

29-Nov-2012 06:37 PM Apple Developer Bug Reporting Team :

We believe this issue has been addressed in the latest Xcode 4.6 Developer Preview.

This is a pre-release version of the Xcode developer toolset for Mac, iPhone, and iPad. It includes the Xcode IDE, iOS Simulator, and all required tools and frameworks for building OS X and iOS apps.  Please verify with this release, and update your bug report with the results.  

Xcode 4.6 Build 4H95e

Posted Date: November 12, 2012

Mac Developers: Log in to the Developer site at https://developer.apple.com/devcenter/mac/index.action

iOS Developers: Log in to the Developer site at https://developer.apple.com/devcenter/ios/index.action# (and click on 'iOS 6.1 SDK beta' tab)

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