Xcode 3.2.6 is the last version of Xcode that supports building kernel extension for Mac OS X 10.4 and 10.5. However, running Xcode 3.2.6 on Mac OS X versions greater than 10.6 is unsupported and requires some tweaking.

Trying to build legacy kernel extension with Xcode 3.2.6 on OS X 10.10 will throw the following error:

dyld: lazy symbol binding failed: Symbol not found: _map_fd
  Referenced from: /Developer/usr/bin/ld_classic
  Expected in: /usr/lib/libSystem.B.dylib

The ld_classic tool included in Xcode 3.2.6 is based on the deprecated map_fd syscall, that is no longer available on OS X 10.10.

This project's libmap_fd.dylib addresses the issue by providing a custom implementation of the map_fd syscall based on mmap, that is compatible with ld_classic. For it to work libmap_fd.dylib needs to be injected into ld_classic. This can be accomplished by setting the following environment variables before invoking ld_classic:

DYLD_FORCE_FLAT_NAMESPACE=1
DYLD_INSERT_LIBRARIES="/path/to/libmap_fd.dylib"

The injection process can be automated by replacing the ld_classic binary with as shell script that sets the above environment variables and calls the original ld_classic tool. See the included ld_classic shell script.