ARM linux的启动部分源代码简略分析

575 __start___param, __stop___param - __start___param,

576 &unknown_bootoption);

577 /*

578 * These use large bootmem allocations and must precede

579 * kmem_cache_init()

580 */

581 pidhash_init();

582 vfs_caches_init_early();

583 sort_main_extable();

584 trap_init();

585 mm_init();

586 /*

587 * Set up the scheduler prior starting any interrupts (such as the

588 * timer interrupt). Full topology setup happens at smp_init()

589 * time - but meanwhile we still have a functioning scheduler.

590 */

591 sched_init();

592 /*

593 * Disable preemption - early bootup scheduling is extremely

594 * fragile until we cpu_idle() for the first time.

595 */

596 preempt_disable();

597 if (!irqs_disabled()) {

598 printk(KERN_WARNING "start_kernel(): bug: interrupts were "

599 "enabled *very* early, fixing it\n");

600 local_irq_disable();

601 }

602 rcu_init();

603 radix_tree_init();

604 /* init some links before init_ISA_irqs() */

605 early_irq_init();

606 init_IRQ();

607 prio_tree_init();

608 init_timers();

609 hrtimers_init();

610 softirq_init();

611 timekeeping_init();

612 time_init();

613 profile_init();

614 if (!irqs_disabled())

615 printk(KERN_CRIT "start_kernel(): bug: interrupts were "

616 "enabled early\n");

617 early_boot_irqs_on();

618 local_irq_enable();

619

620 /* Interrupts are enabled now so all GFP allocations are safe. */

621 gfp_allowed_mask = __GFP_BITS_MASK;

622

623 kmem_cache_init_late();

624

625 /*

626 * HACK ALERT! This is early. Were enabling the console before

627 * weve done PCI setups etc, and console_init() must be aware of

628 * this. But we do want output early, in case something goes wrong.

629 */

630 console_init();

631 if (panic_later)

632 panic(panic_later, panic_param);

633

634 lockdep_info();

635

636 /*

637 * Need to run this when irqs are enabled, because it wants

638 * to self-test [hard/soft]-irqs on/off lock inversion bugs

639 * too:

640 */

641 locking_selftest();

642

643 #ifdef CONFIG_BLK_DEV_INITRD

644 if (initrd_start && !initrd_below_start_ok &&

645 page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {

646 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "

647 "disabling it.\n",

648 page_to_pfn(virt_to_page((void *)initrd_start)),

649 min_low_pfn);

650 initrd_start = 0;

651 }

652 #endif

653 page_cgroup_init();

654 enable_debug_pagealloc();

655 kmemtrace_init();

656 kmemleak_init();

657 debug_objects_mem_init();

658 idr_init_cache();

659 setup_per_cpu_pageset();

660 numa_policy_init();

661 if (late_time_init)

662 late_time_init();

663 sched_clock_init();

664 calibrate_delay();

665 pidmap_init();

666 anon_vma_init();

667 #ifdef CONFIG_X86

668 if (efi_enabled)

669 efi_enter_virtual_mode();

670 #endif

671 thread_info_cache_init();

672 cred_init();

673 fork_init(totalram_pages);

674 proc_caches_init();

675 buffer_init();

676 key_init();

677 security_init();

678 vfs_caches_init(totalram_pages);

679 signals_init();

680 /* rootfs populating might need page-writeback */

681 page_writeback_init();

682 #ifdef CONFIG_PROC_FS

683 proc_root_init();

684 #endif

685 cgroup_init();

686 cpuset_init();

687 taskstats_init_early();

688 delayacct_init();

689

690 check_bugs();

691

692 acpi_early_init(); /* before LAPIC and SMP init */

693 sfi_init_late();

694

695 ftrace_init();

696

697 /* Do the rest non-__inited, were now alive */

698 rest_init();

699 }

接着我们来近距离的观察一下start_kernel函数中调用的这些重量级的函数。

首先来看setup_arch(&command_line)函数，这个函数（对于我们的mini2440平台来说）在arch/arm/kernel/setup.c中定义：

664 void __init setup_arch(char cmdline_p)

665 {

666 struct tag *tags = (struct tag *)&init_tags;

667 struct machine_desc *mdesc;

668 char *from = default_command_line;

669

670 unwind_init();

671

672 setup_processor();