I have fixed and compiled xnu-1504.9.17 or 10.6.5 kernel. I had added " /* NMI: ummasked, off course */
LAPIC_WRITE(LVT_LINT1, LAPIC_LVT_DM_NMI);" and that way machines with issues with lapic.c con boot up without "CPUS=" and load all cores.

so the code will look like this:
----------------------------------------------------------
}

/* Set flat delivery model, logical processor id */
LAPIC_WRITE(DFR, LAPIC_DFR_FLAT);
LAPIC_WRITE(LDR, (get_cpu_number()) << LAPIC_LDR_SHIFT);

/* Accept all */
LAPIC_WRITE(TPR, 0);

LAPIC_WRITE(SVR, LAPIC_VECTOR(SPURIOUS) | LAPIC_SVR_ENABLE);

/* ExtINT */
if (get_cpu_number() == master_cpu) {
value = LAPIC_READ(LVT_LINT0);
value &= ~LAPIC_LVT_MASKED;
value |= LAPIC_LVT_DM_EXTINT;
LAPIC_WRITE(LVT_LINT0, value);
}

/* NMI: ummasked, off course */
LAPIC_WRITE(LVT_LINT1, LAPIC_LVT_DM_NMI);


/* Timer: unmasked, one-shot */
LAPIC_WRITE(LVT_TIMER, LAPIC_VECTOR(TIMER));

/* Perfmon: unmasked */
LAPIC_WRITE(LVT_PERFCNT, LAPIC_VECTOR(PERFCNT));

/* Thermal: unmasked */
LAPIC_WRITE(LVT_THERMAL, LAPIC_VECTOR(THERMAL));



------------------------------------------------------------





Here is a Vanilla Kernel 10.6.4 that has lapic issue fixed (that affect HP's laptops).

Installing or replacing the kernel will give you the option of booting up 64 bit mode, not with the Legacy kernel which work on 32 bit only. So, the kernel works great same as the Legacy kernel, loading all 4 cores/8 threads but on 64 bit mode.

10.6.5 mach kernel (Mediafire)

10.6.5 mach kernel (Megaupload)

I have added in the mach_kernel folder "i386, X86_64 and Universal Binary Kernel (meanings both).


If you're booting up from your Hard drive remember to replace the mach_kernel from both, system root and preboot.dmg


Enjoy it...