【linux】【init】【main.c】start_kernel函数

林子

linux启动的C语言部分的主函数如下： 我先粘贴整个函数部分，后续对每个函数展开讲解。

asmlinkage void __init start_kernel(void)
{
char * command_line;
extern const struct kernel_param __start___param[], __stop___param[];
smp_setup_processor_id();
/*
  * Need to run as early as possible, to initialize the
  * lockdep hash:
  */
lockdep_init();
debug_objects_early_init();
/*
  * Set up the the initial canary ASAP:
  */
boot_init_stack_canary();
cgroup_init_early();
local_irq_disable();
early_boot_irqs_disabled = true;
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
*/
tick_init();
boot_cpu_init();
page_address_init();
printk(KERN_NOTICE "%s", linux_banner);
setup_arch(&command_line);
mm_init_owner(&init_mm, &init_task);
mm_init_cpumask(&init_mm);
setup_command_line(command_line);
setup_nr_cpu_ids();
setup_per_cpu_areas();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
build_all_zonelists(NULL);
page_alloc_init();
printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
parse_early_param();
parse_args("Booting kernel", static_command_line, __start___param,   __stop___param - __start___param,  &unknown_bootoption);
/*
  * These use large bootmem allocations and must precede
  * kmem_cache_init()
  */
setup_log_buf(0);
pidhash_init();
vfs_caches_init_early();   //虚拟文件系统早期初始化
sort_main_extable();
trap_init();

//memblock_reserve((phys_addr_t)0x50000000,(phys_addr_t)0x100000);
mm_init();
/*
  * Set up the scheduler prior starting any interrupts (such as the
  * timer interrupt). Full topology setup happens at smp_init()
  * time - but meanwhile we still have a functioning scheduler.
  */
sched_init();
/*
  * Disable preemption - early bootup scheduling is extremely
  * fragile until we cpu_idle() for the first time.
  */
preempt_disable();
if (!irqs_disabled())
{
  printk(KERN_WARNING "start_kernel(): bug: interrupts were enabled *very* early, fixing it\n");
  local_irq_disable();
}
idr_init_cache();
perf_event_init();
rcu_init();
radix_tree_init();
/* init some links before init_ISA_irqs() */
early_irq_init();
init_IRQ();
prio_tree_init();
init_timers();
hrtimers_init();
softirq_init();
timekeeping_init();
time_init();
profile_init();
call_function_init();
if (!irqs_disabled())
  printk(KERN_CRIT "start_kernel(): bug: interrupts were enabled early\n");
early_boot_irqs_disabled = false;
local_irq_enable();
/* Interrupts are enabled now so all GFP allocations are safe. */
gfp_allowed_mask = __GFP_BITS_MASK;
kmem_cache_init_late();
/*
  * HACK ALERT! This is early. We're enabling the console before
  * we've done PCI setups etc, and console_init() must be aware of
  * this. But we do want output early, in case something goes wrong.
  */
console_init();
if (panic_later)
  panic(panic_later, panic_param);
lockdep_info();
/*
  * Need to run this when irqs are enabled, because it wants
  * to self-test [hard/soft]-irqs on/off lock inversion bugs
  * too:
  */
locking_selftest();
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
     page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn)
{
  printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
        page_to_pfn(virt_to_page((void *)initrd_start)), min_low_pfn);
  initrd_start = 0;
}
#endif
page_cgroup_init();
enable_debug_pagealloc();
debug_objects_mem_init();
kmemleak_init();
setup_per_cpu_pageset();
numa_policy_init();
if (late_time_init)
  late_time_init();
sched_clock_init();
calibrate_delay();
pidmap_init();
anon_vma_init();
#ifdef CONFIG_X86
if (efi_enabled)
  efi_enter_virtual_mode();
#endif
thread_info_cache_init();
cred_init();
fork_init(totalram_pages);
proc_caches_init();
buffer_init();
key_init();
security_init();
dbg_late_init();
vfs_caches_init(totalram_pages);  //虚拟文件系统初始化
signals_init();
/* rootfs populating might need page-writeback */
page_writeback_init();
#ifdef CONFIG_PROC_FS
proc_root_init();
#endif
cgroup_init();
cpuset_init();
taskstats_init_early();
delayacct_init();
check_bugs();
acpi_early_init(); /* before LAPIC and SMP init */
sfi_init_late();
ftrace_init();
/* Do the rest non-__init'ed, we're now alive */
//printk(KERN_INFO "[mjdbg]MEM Check4:0x%x : 0x%x.\n", (int *)(phys_to_virt(0x50000000)),*(int *)(phys_to_virt(0x50000000)));
rest_init();
}

林子

start_kernel函数最后的函数rest_init函数代码如下
static noinline void __init_refok rest_init(void)
{
        int pid;
        //printk("**********************************************************\n");
        //printk(" rest_init: 0x%x!!!\n",(*(int *)phys_to_virt(0x50000000)));
        //printk("**********************************************************\n");

#ifdef CONFIG_KERNEL_PANIC_DUMP
        panic_dump_test();
#endif       


        rcu_scheduler_starting();
        /*
         * We need to spawn init first so that it obtains pid 1, however
         * the init task will end up wanting to create kthreads, which, if
         * we schedule it before we create kthreadd, will OOPS.
         */
        kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
        numa_default_policy();
        pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
        rcu_read_lock();
        kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
        rcu_read_unlock();
        complete(&kthreadd_done);

        /*
         * The boot idle thread must execute schedule()
         * at least once to get things moving:
         */
        init_idle_bootup_task(current);
        preempt_enable_no_resched();
        schedule();
        preempt_disable();

        /* Call into cpu_idle with preempt disabled */
        cpu_idle();
}