SMP init

#define NR_CPUS         CONFIG_NR_CPUS // CONFIG_NR_CPUS was set in .config file

unsigned int setup_max_cpus = NR_CPUS;

void __init smp_init(void)

{

        unsigned int cpu;

        /* FIXME: This should be done in userspace --RR */

        for_each_present_cpu(cpu) {

                if (num_online_cpus() >= setup_max_cpus)

                        break;

                if (!cpu_online(cpu))

                        cpu_up(cpu);

        }

        /* Any cleanup work */

        printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());

        smp_cpus_done(setup_max_cpus);

}

cpu_up(cpu)

_cpu_up(cpu, 0)

__cpu_up(cpu)// in arch/arm/kernel/smp.c

boot_secondary() //in mach-xxxx/platsmp.c

gic_raise_softirq(cpumask_of(cpu), 1);

 b       secondary_start_kernel //arch/arm/kernel/head.S

 secondary_start_kernel()// in arch/arm/kernel/smp.c

printk("CPU%u: Booted secondary processor\n", cpu);

set_cpu_online(cpu, true);

log:

[    0.257168] CPU1: Booted secondary processor

[    0.290003] CPU1: Unknown IPI message 0x1

[    0.290027] Brought up 2 CPUs

[    0.290039] SMP: Total of 2 processors activated (2393.70 BogoMIPS).