This is xnu-8019. See this file in:
Directory listing for xnu-8019//osfmk/i386
AT386/
Diagnostics.c
Diagnostics.h
Makefile
acpi.c
acpi.h
apic.h
arch_types.h
asm.h
asm64.h
atomic.h
bit_routines.h
bsd_i386.c
bsd_i386_native.c
commpage/
cpu.c
cpu_affinity.h
cpu_capabilities.h
cpu_data.h
cpu_number.h
cpu_threads.c
cpu_threads.h
cpu_topology.c
cpu_topology.h
cpuid.c
cpuid.h
eflags.h
endian.h
exec.h
fp_simd.s
fpu.c
fpu.h
gdt.c
genassym.c
hibernate_i386.c
hibernate_restore.c
hpet.c
hpet.h
hw_defs.h
hw_lock_types.h
i386_init.c
i386_lock.s
i386_lowmem.h
i386_timer.c
i386_vm_init.c
io_map.c
io_map_entries.h
io_port.h
iopb.h
ktss.c
lapic.c
lapic.h
lapic_native.c
lbr.h
ldt.c
lock.h
locks.h
locks_i386.c
locks_i386_inlines.h
locks_i386_opt.c
machdep_call.c
machdep_call.h
machine_check.c
machine_check.h
machine_cpu.h
machine_routines.c
machine_routines.h
machine_rpc.h
machine_task.c
machlimits.h
machparam.h
memory_types.h
misc_protos.h
mp.c
mp.h
mp_desc.c
mp_desc.h
mp_events.h
mp_native.c
mtrr.c
mtrr.h
pal_hibernate.h
pal_lock_asm.h
pal_native.h
pal_routines.c
pal_routines.h
pal_rtclock_asm.h
panic_hooks.c
panic_hooks.h
panic_notify.c
panic_notify.h
pcb.c
pcb_native.c
phys.c
pio.h
pmCPU.c
pmCPU.h
pmap.h
pmap_common.c
pmap_internal.h
pmap_pcid.h
pmap_x86_common.c
postcode.h
proc_reg.h
rtclock.c
rtclock_asm.h
rtclock_asm_native.h
rtclock_native.c
rtclock_protos.h
sched_param.h
seg.h
serial_io.h
setjmp.h
simple_lock.h
smp.h
stab.h
task.h
thread.h
trap.c
trap.h
trap_native.c
tsc.c
tsc.h
tss.h
ucode.c
ucode.h
user_ldt.c
user_ldt.h
vm_tuning.h
vmx/
vmx.h
x86_hypercall.c
x86_hypercall.h