没有定义 SYS_SUPPORTS_MULTITHREADING的话就不会定义CONFIG_MIPS_MT_SMTC

SYS_SUPPORTS_MULTITHREADING：
config SYS_SUPPORTS_MULTITHREADING
 bool
config MIPS_MALTA
config MIPS_SIM
config MIPS_MT_SMP
config MIPS_MT_SMTC
config MIPS_VPE_LOADER
 select SYS_SUPPORTS_MULTITHREADING

CONFIG_MIPS_MT_SMTC：
config MIPS_MT_SMTC
 bool "SMTC: Use all TCs on all VPEs for SMP"
 depends on CPU_MIPS32_R2
 #depends on CPU_MIPS64_R2  # once there is hardware ...
 depends on SYS_SUPPORTS_MULTITHREADING
 select CPU_MIPSR2_IRQ_VI
 select CPU_MIPSR2_IRQ_EI
 select MIPS_MT
 select NR_CPUS_DEFAULT_8
 select SMP
 select SYS_SUPPORTS_SMP
 select SMP_UP
 help
   This is a kernel model which is known a SMTC or lately has been
   marketesed into SMVP.
config ARCH_SUPPORTS_OPROFILE
 bool
 default y if !MIPS_MT_SMTC