HOST_MIN_STACK_SIZE   27 arch/powerpc/kvm/booke_interrupts.S #define HOST_MIN_STACK_SIZE (HOST_NV_GPR(R31) + 4)
HOST_MIN_STACK_SIZE   46 arch/powerpc/kvm/bookehv_interrupts.S #define HOST_MIN_STACK_SIZE (HOST_NV_GPR(R31) + LONGBYTES)