On a Linux host the driver sets the environment of the
scripts/linux/setup-toolchain.py toolchain: the xcrun shim answers SDK
queries with the build tree's fakeroot, clang targets plain arm64 for
iOS 17, and CCC_OVERRIDE_OPTIONS turns off two warnings upstream clang
has and Apple clang does not (the archive builders use -Werror and
replay xnu's compile records, so only the clang driver sees them).
- build-xnu-4k-baseline.sh runs scripts/linux/prepare-xnu.py: source
rewrites the xnu sources that assume Apple's tools (SHA/AES assembler
macros, makesyscalls.sh under mawk, kextsymboltool and /dev/null) and
installs TargetConditionals.h into the fakeroot; libs builds
libcc_kext.a from compiler-rt's cc_kext profile sources. xnu's make
also gets the host compiler, mig and the machine sizes a Mac supplies.
ditto becomes cp.
- build-firehose.sh compiles libfirehose_kernel from its xcconfig.
- build-corecrypto-14.py reads project.pbxproj with scripts/pbxproj.py
(same JSON as plutil for all 13,112 objects).
- The kernelcache is decoded with lzfse.
The macOS path is unchanged apart from ditto. Built from the same
sources and configuration on Linux and with Xcode 27.1, the kernels have
the same global symbols, linked objects, archive symbols, 1,265
kalloc_type signatures, and prelink bindings and kexts.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
scripts/linux/setup-toolchain.py, run once as root, builds into
/opt/unixnu-linux (or PREFIX, or $UNIXNU_TOOLCHAIN):
- clang from llvm-project 58c46bae2118 with llvm-xnu-builtin-type.patch,
which adds __builtin_xnu_type_signature, __builtin_xnu_type_summary,
__builtin_xnu_types_compatible and xnu_usage_semantics; kalloc.h uses
the builtins with no fallback;
- cctools-port 1030.6.3-ld64-956.6 (its master, ld64-609, corrupts the
kernel link), with libdispatch for ld64;
- mig and migcom from bootstrap_cmds-138;
- iig-port, with iig-port-darwin-target.patch;
- xnu-host-cc, the host compiler for xnu's SETUP tools;
- lzfse for the kernelcache.
It installs the Command Line Tools shims (clang, clang++, cc, install,
gm4) under the prefix and xcrun, plutil and codesign in /usr/bin, where
xnu's makefiles call them. libmacho.a and libstuff.a go to /usr/lib and
libdispatch to /usr/local. Each step is skipped when its output exists.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
rponeawa