MetallibSupportPkg

MetallibSupportPkg

A collection of utilities related to patching Metal Libraries (.metallib) in macOS, specifically with the goal of restoring support for legacy hardware (namely Metal 3802-based GPUs on macOS Sequoia).

Logic

MetallibSupportPkg houses the metal_libraries python library, which was developed to streamline Metal Library patching through the following:

1. Programmatically fetching the latest macOS Sequoia IPSW.
2. Extract the system volume DMG from the IPSW.
3. If the disk image is AEA encrypted, decrypt using aastuff.
4. Mount the disk image, and extract all supported .metallib files.
5. Patch the .metallib files to support Metal 3802 GPUs.
6. Convert the directory into a macOS Distribution Package (PKG).

Notes regarding patching individual .metallib files:

1. Each .metallib file is actually a collection of .air files. Need to extract them using zhouwei's format.
   • metallib/patch.py: _unpack_metallib_to_air()
2. Certain .metallib files are actually FAT Mach-O files. Thus they need to be thinned manually (Apple's lipo utility does not support the AIR64 architecture we need).
   • metallib/patch.py: _thin_file()
3. .air files need to be next decompiled to .ll (LLVM IR) using Apple's metal-objdump utility.
   • metallib/patch.py: _decompile_air_to_ll()
4. With the LLVM IR, we can begin patching the AIR version to v26 (compared to Sequoia's v27) as well as other necessary changes.
   • metallib/patch.py: _patch_ll()
5. To compile IR to .air, we use Apple's metal utility.
   • metallib/patch.py: _recompile_ll_to_air()
6. To pack each .air to a .metallib collection, we use Apple's metallib utility.
   • metallib/patch.py: _pack_air_to_metallib()

Once finished, the resulting .metallib files should work with Metal 3802-based GPUs in macOS Sequoia.

Usage

MetallibSupportPkg is not meant to be used by general users, the following is intended for developers.

Install the required dependencies:

python3 -m pip install -r requirements.txt
# Note Xcode is required to be installed for the `metal` and `metal-objdump` utilities

Fetch IPSW URL:

python3 metallib.py -d
# Example result: UniversalMac_15.0_24A5279h_Restore.ipsw

Extract system volume from IPSW:

python3 metallib.py -e <path_to_ipsw>
# Example result: 090-49684-056.dmg

Fetch Metal libraries from system volume, will extract to 15.x-:

python3 metallib.py -f <path_to_system_volume>
# Example result: 15.0-24A5279h

Patch Metal libraries:

# Directory containing the Metal libraries
python3 metallib.py -p <path_to_metallib_dir>
# Individual Metal library
python3 metallib.py -p <path_to_metallib>

Convert Metal libraries to macOS package:

python3 metallib.py -z <path_to_metallib_dir>
# Example result: MetallibSupportPkg-15.0-24A5279h.pkg

---

usage: metallib.py [-h] [-d] [-e EXTRACT] [-f FETCH] [-p PATCH] [-b BUILD_SYS_PATCH] [-z BUILD_PKG] [-c]

Download, extract, fetch, and patch Metal libraries.

options:
  -h, --help            show this help message and exit
  -d, --download        Download the latest IPSW.
  -e EXTRACT, --extract EXTRACT
                        Extract the system volume from an IPSW.
  -f FETCH, --fetch FETCH
                        Fetch Metal libraries from the system volume.
  -p PATCH, --patch PATCH
                        Patch Metal libraries.
  -b BUILD_SYS_PATCH, --build-sys-patch BUILD_SYS_PATCH
                        Build a system patch dictionary.
  -z BUILD_PKG, --build-pkg BUILD_PKG
                        Build a macOS package.
  -c, --continuous-integration
                        Run in continuous integration mode.