CONFIG_SMP is not available for thedefaultarchitecture x86.
Result is shown for architecture sparc64

Symmetric multi-processing support

modulename: ip27-smp.ko

and/or

platsmp.ko

and/or

smp.ko

and/or

mpc86xx_smp.ko

and/or

topology.ko

and/or

percpu_counter.ko

and/or

allocpercpu.ko

and/or

trampoline.ko

and/or

malta_smp.ko

and/or

sim_smp.ko

and/or

q-smp.ko

and/or

voyager_smp.ko

and/or

locks.ko

and/or

cpu.ko

configname: CONFIG_SMP

Linux/UltraSPARC Kernel Configuration
└─>General machine setup
└─>Symmetric multi-processing support
In linux kernel since version 2.6.12  
This enables support for systems with more than one CPU. If you have
a system with only one CPU, say N. If you have a system with more than
one CPU, say Y.

If you say N here, the kernel will run on single and multiprocessor
machines, but will use only one CPU of a multiprocessor machine. If
you say Y here, the kernel will run on many, but not all,
singleprocessor machines. On a singleprocessor machine, the kernel
will run faster if you say N here.

People using multiprocessor machines who say Y here should also say
Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
Management" code will be disabled if you say Y here.

See also the Documentation/smp.txt,
Documentation/nmi_watchdog.txt and the SMP-HOWTO available at
<http://www.tldp.org/docs.html#howto>.

If you don't know what to do here, say N.