Friday, October 31, 2014

Building xnu for OS X 10.10 Yosemite

The OS X kernel source (xnu) has been released for OS X 10.10 Yosemite: here

Building xnu requires Xcode and some additional open-source (but not pre-installed) dependencies. You can build xnu manually by doing:


  1. Install OS X Yosemite and Xcode 6.1 from the Mac App Store, make sure the Xcode license has been agreed-to with "sudo xcodebuild -license"
  2. Download the source for the dtrace and AvailabilityVersions projects, which are required dependencies, as well as xnu itself
    $ curl -O http://opensource.apple.com/tarballs/dtrace/dtrace-147.tar.gz
    $ curl -O http://opensource.apple.com/tarballs/AvailabilityVersions/AvailabilityVersions-9.tar.gz
    $ curl -O http://opensource.apple.com/tarballs/xnu/xnu-2782.1.97.tar.gz
  3. Build and install CTF tools from dtrace
    $ tar zxf dtrace-147.tar.gz
    $ cd dtrace-147
    $ mkdir -p obj sym dst
    $ xcodebuild install -target ctfconvert -target ctfdump -target ctfmerge ARCHS="x86_64" SRCROOT=$PWD OBJROOT=$PWD/obj SYMROOT=$PWD/sym DSTROOT=$PWD/dst
    ...
    $ sudo ditto $PWD/dst/usr/local /usr/local
    Password:
    $ cd ..
    
  4. Install AvailabilityVersions
    $ tar zxf AvailabilityVersions-9.tar.gz
    $ cd AvailabilityVersions-9
    $ mkdir -p dst
    $ make install SRCROOT=$PWD DSTROOT=$PWD/dst
    $ sudo ditto $PWD/dst/usr/local `xcrun -sdk macosx -show-sdk-path`/usr/local
    $ cd ..
    
  5. Build xnu
    $ tar zxf xnu-2782.1.97.tar.gz
    $ cd xnu-2782.1.97
    $ make SDKROOT=macosx ARCH_CONFIGS=X86_64 KERNEL_CONFIGS=RELEASE
See xnu's top-level README for additional build variables that can be passed on the command-line, such as BUILD_LTO=0 .

Update: If you are attempting to add system calls, you may also need to build Libsyscall.


  1. Download the Libsystem source
    $ curl -O http://opensource.apple.com/tarballs/Libsystem/Libsystem-1213.tar.gz
    
  2. Install Libsystem headers
    $ tar zxf Libsystem-1213.tar.gz 
    $ cd Libsystem-1213
    $ xcodebuild installhdrs -sdk macosx ARCHS='x86_64 i386' SRCROOT=$PWD OBJROOT=$PWD/obj SYMROOT=$PWD/sym DSTROOT=$PWD/dst
    $ sudo ditto $PWD/dst `xcrun -sdk macosx -show-sdk-path`
    $ cd ..
    
  3. Install xnu and Libsyscall headers
    $ cd xnu-2782.1.97
    $ mkdir -p BUILD.hdrs/obj BUILD.hdrs/sym BUILD.hdrs/dst
    $ make installhdrs SDKROOT=macosx ARCH_CONFIGS=X86_64 SRCROOT=$PWD OBJROOT=$PWD/BUILD.hdrs/obj SYMROOT=$PWD/BUILD.hdrs/sym DSTROOT=$PWD/BUILD.hdrs/dst
    $ xcodebuild installhdrs -project libsyscall/Libsyscall.xcodeproj -sdk macosx ARCHS='x86_64 i386' SRCROOT=$PWD/libsyscall OBJROOT=$PWD/BUILD.hdrs/obj SYMROOT=$PWD/BUILD.hdrs/sym DSTROOT=$PWD/BUILD.hdrs/dst
    $ sudo ditto BUILD.hdrs/dst `xcrun -sdk macosx -show-sdk-path`
  4. Build Libsyscall
    $ mkdir -p BUILD.libsyscall/obj BUILD.libsyscall/sym BUILD.libsyscall/dst
    $ xcodebuild install -project libsyscall/Libsyscall.xcodeproj -sdk macosx ARCHS='x86_64 i386' SRCROOT=$PWD/libsyscall OBJROOT=$PWD/BUILD.libsyscall/obj SYMROOT=$PWD/BUILD.libsyscall/sym DSTROOT=$PWD/BUILD.libsyscall/dst