{"id":347,"date":"2018-03-14T09:45:18","date_gmt":"2018-03-14T01:45:18","guid":{"rendered":"http:\/\/www.max-shu.com\/blog\/?p=347"},"modified":"2018-03-14T09:45:18","modified_gmt":"2018-03-14T01:45:18","slug":"linux%e7%9a%84init-main-c","status":"publish","type":"post","link":"http:\/\/www.max-shu.com\/blog\/?p=347","title":{"rendered":"linux\u7684init\/Main.c"},"content":{"rendered":"
\u4ecehead-common.S\u8c03\u7528\u4e86start_kernel\u51fd\u6570\uff0c\u5c31\u5b9a\u4e49\u5728\u8fd9\u4e2a\u6587\u4ef6\u4e2d\uff0c\u8fd9\u91cc\u662f\u5185\u6838\u7684c\u51fd\u6570\u5165\u53e3\u70b9\u3002<\/div>\n
<\/div>\n
\u8fd9\u91cc\u5bf9\u6574\u4e2a\u7cfb\u7edf\u5185\u5b58\u3001cache\u3001\u4fe1\u53f7\u3001\u8bbe\u5907\u7b49\u8fdb\u884c\u521d\u59cb\u5316\uff0c\u6700\u540e\u751f\u6210init\u8fdb\u7a0b\u540e\uff0c\u8c03\u7528cpu_idle()\u5b8c\u6210\u5185\u6838\u542f\u52a8\u3002<\/strong><\/span><\/div>\n
<\/div>\n
asmlinkage void __init start_kernel(void)
\n{
\nchar * command_line;
\nextern struct kernel_param __start___param[], __stop___param[];<\/p>\n

smp_setup_processor_id();<\/p>\n

\/*
\n* Need to run as early as possible, to initialize the
\n* lockdep hash:
\n*\/
\nunwind_init();
\nlockdep_init();
\ndebug_objects_early_init();
\ncgroup_init_early();<\/p>\n

local_irq_disable();
\nearly_boot_irqs_off();
\nearly_init_irq_lock_class();<\/p>\n

\/*
\n* Interrupts are still disabled. Do necessary setups, then
\n* enable them
\n*\/
\nlock_kernel();
\ntick_init();
\nboot_cpu_init();
\npage_address_init();
\nprintk(KERN_NOTICE);
\nprintk(linux_banner);
\nsetup_arch(&command_line);
\nmm_init_owner(&init_mm, &init_task);
\nsetup_command_line(command_line);
\nunwind_setup();
\nsetup_per_cpu_areas();
\nsetup_nr_cpu_ids();
\nsmp_prepare_boot_cpu();\u00a0\u00a0\u00a0\u00a0 \/* arch-specific boot-cpu hooks *\/<\/p>\n

\/*
\n* Set up the scheduler prior starting any interrupts (such as the
\n* timer interrupt). Full topology setup happens at smp_init()
\n* time – but meanwhile we still have a functioning scheduler.
\n*\/
\nsched_init();
\n\/*
\n* Disable preemption – early bootup scheduling is extremely
\n* fragile until we cpu_idle() for the first time.
\n*\/
\npreempt_disable();
\nbuild_all_zonelists();
\npage_alloc_init();
\nprintk(KERN_NOTICE “Kernel command line: %s\\n”, boot_command_line);
\nparse_early_param();
\nparse_args(“Booting kernel”, static_command_line, __start___param,
\n__stop___param – __start___param,
\n&unknown_bootoption);
\nif (!irqs_disabled()) {
\nprintk(KERN_WARNING “start_kernel(): bug: interrupts were ”
\n“enabled *very* early, fixing it\\n”);
\nlocal_irq_disable();
\n}
\nsort_main_extable();
\ntrap_init();
\nrcu_init();
\ninit_IRQ();
\npidhash_init();
\ninit_timers();
\nhrtimers_init();
\nsoftirq_init();
\ntimekeeping_init();
\ntime_init();
\nsched_clock_init();
\nprofile_init();
\nif (!irqs_disabled())
\nprintk(“start_kernel(): bug: interrupts were enabled early\\n”);
\nearly_boot_irqs_on();
\nlocal_irq_enable();<\/p>\n

\/*
\n* HACK ALERT! This is early. We’re enabling the console before
\n* we’ve done PCI setups etc, and console_init() must be aware of
\n* this. But we do want output early, in case something goes wrong.
\n*\/
\nconsole_init();
\nif (panic_later)
\npanic(panic_later, panic_param);<\/p>\n

lockdep_info();<\/p>\n

\/*
\n* Need to run this when irqs are enabled, because it wants
\n* to self-test [hard\/soft]-irqs on\/off lock inversion bugs
\n* too:
\n*\/
\nlocking_selftest();<\/p>\n

#ifdef CONFIG_BLK_DEV_INITRD
\nif (initrd_start && !initrd_below_start_ok &&
\npage_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
\nprintk(KERN_CRIT “initrd overwritten (0x%08lx < 0x%08lx) – ”
\n“disabling it.\\n”,
\npage_to_pfn(virt_to_page((void *)initrd_start)),
\nmin_low_pfn);
\ninitrd_start = 0;
\n}
\n#endif
\nvmalloc_init();
\nvfs_caches_init_early();
\ncpuset_init_early();
\npage_cgroup_init();
\nmem_init();
\nenable_debug_pagealloc();
\ncpu_hotplug_init();
\nkmem_cache_init();
\ndebug_objects_mem_init();
\nidr_init_cache();
\nsetup_per_cpu_pageset();
\nnuma_policy_init();
\nif (late_time_init)
\nlate_time_init();
\ncalibrate_delay();
\npidmap_init();
\npgtable_cache_init();
\nprio_tree_init();
\nanon_vma_init();
\n#ifdef CONFIG_X86
\nif (efi_enabled)
\nefi_enter_virtual_mode();
\n#endif
\nthread_info_cache_init();
\nfork_init(num_physpages);
\nproc_caches_init();
\nbuffer_init();
\nkey_init();
\nsecurity_init();
\nvfs_caches_init(num_physpages);
\nradix_tree_init();
\nsignals_init();
\n\/* rootfs populating might need page-writeback *\/
\npage_writeback_init();
\n#ifdef CONFIG_PROC_FS
\nproc_root_init();
\n#endif
\ncgroup_init();
\ncpuset_init();
\ntaskstats_init_early();
\ndelayacct_init();<\/p>\n

check_bugs();<\/p>\n

acpi_early_init(); \/* before LAPIC and SMP init *\/<\/p>\n

ftrace_init();<\/p>\n

\/* Do the rest non-__init’ed, we’re now alive *\/
\nrest_init(); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/*\u8fdb\u5165\u5269\u4f59\u521d\u59cb\u5316\uff0c\u5c31\u662f\u521d\u59cb\u5316init\u8fdb\u7a0b*\/
\n}<\/p><\/div>\n

<\/div>\n
static void noinline __init_refok rest_init(void) \u00a0 \/*\u5176\u4f59\u7684\u521d\u59cb\u5316*\/
\n__releases(kernel_lock)
\n{
\nint pid;<\/p>\n

kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND); \u00a0 \u00a0\/*\u542f\u52a8init\u8fdb\u7a0b\uff0c\u5165\u53e3\u4e3akernel_init()\u3002*\/
\nnuma_default_policy();
\npid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES); \u00a0\/*\u542f\u52a8kthread\u8fdb\u7a0b\uff0c\u5165\u53e3\u4e3akthreadd\uff0c\u5b9a\u4e49\u5728kthread.c\u3002\u5b83\u5c06\u4f1a\u5bf9\u6bcf\u4e2acpu\u5efa\u7acb\u5f88\u591a\u8bbe\u5907\u7684\u5185\u6838\u5b50\u8fdb\u7a0b*\/
\nkthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
\nunlock_kernel();<\/p>\n

\/*
\n* The boot idle thread must execute schedule()
\n* at least once to get things moving:
\n*\/
\ninit_idle_bootup_task(current);
\npreempt_enable_no_resched();
\nschedule();
\npreempt_disable();<\/p>\n

\/* Call into cpu_idle with preempt disabled *\/
\ncpu_idle(); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/*\u8c03\u7528cpu_idle\uff0c\u5373\u8c03\u7528pm_idle\uff0c\u6700\u7ec8\u8c03\u7528cpuidle_idle_call\u3002*\/
\n}<\/p><\/div>\n

<\/div>\n
static int __init kernel_init(void * unused) \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/*init\u8fdb\u7a0b*\/
\n{
\nlock_kernel();
\n\/*
\n* init can run on any cpu.
\n*\/
\nset_cpus_allowed_ptr(current, CPU_MASK_ALL_PTR);
\n\/*
\n* Tell the world that we’re going to be the grim
\n* reaper of innocent orphaned children.
\n*
\n* We don’t want people to have to make incorrect
\n* assumptions about where in the task array this
\n* can be found.
\n*\/
\ninit_pid_ns.child_reaper = current;<\/p>\n

cad_pid = task_pid(current);<\/p>\n

smp_prepare_cpus(setup_max_cpus);<\/p>\n

do_pre_smp_initcalls();
\nstart_boot_trace();<\/p>\n

smp_init();
\nsched_init_smp();<\/p>\n

cpuset_init_smp();<\/p>\n

do_basic_setup();<\/p>\n

\/*
\n* check if there is an early userspace init.\u00a0 If yes, let it do all
\n* the work
\n*\/<\/p>\n

if (!ramdisk_execute_command)
\nramdisk_execute_command = “\/init”;<\/p>\n

if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
\nramdisk_execute_command = NULL;
\nprepare_namespace();
\n}<\/p>\n

\/*
\n* Ok, we have completed the initial bootup, and
\n* we’re essentially up and running. Get rid of the
\n* initmem segments and start the user-mode stuff..
\n*\/
\nstop_boot_trace();
\ninit_post();
\nreturn 0;
\n}<\/p><\/div>\n

<\/div>\n
static int noinline init_post(void)
\n{
\nfree_initmem();
\nunlock_kernel();
\nmark_rodata_ro();
\nsystem_state = SYSTEM_RUNNING;
\nnuma_default_policy();<\/p>\n

if (sys_open((const char __user *) “\/dev\/console”, O_RDWR, 0) < 0)
\nprintk(KERN_WARNING “Warning: unable to open an initial console.\\n”);<\/p>\n

(void) sys_dup(0);
\n(void) sys_dup(0);<\/p>\n

current->signal->flags |= SIGNAL_UNKILLABLE;<\/p>\n

if (ramdisk_execute_command) {
\nrun_init_process(ramdisk_execute_command);
\nprintk(KERN_WARNING “Failed to execute %s\\n”,
\nramdisk_execute_command);
\n}<\/p>\n

\/*
\n* We try each of these until one succeeds.
\n*
\n* The Bourne shell can be used instead of init if we are
\n* trying to recover a really broken machine.
\n*\/
\nif (execute_command) {
\nrun_init_process(execute_command);
\nprintk(KERN_WARNING “Failed to execute %s.\u00a0 Attempting ”
\n“defaults…\\n”, execute_command);
\n}
\nrun_init_process(“\/sbin\/init”);
\nrun_init_process(“\/etc\/init”);
\nrun_init_process(“\/bin\/init”);
\nrun_init_process(“\/bin\/sh”);<\/p>\n

panic(“No init found.\u00a0 Try passing init= option to kernel.”);
\n}<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

\u4ecehead-common.S\u8c03\u7528\u4e86start_kernel\u51fd\u6570\uff0c\u5c31\u5b9a\u4e49\u5728\u8fd9\u4e2a\u6587\u4ef6\u4e2d\uff0c\u8fd9\u91cc\u662f\u5185\u6838\u7684c\u51fd\u6570\u5165\u53e3\u70b9\u3002 …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15],"tags":[9,234,243,244],"class_list":["post-347","post","type-post","status-publish","format-standard","hentry","category-linuxandroid","tag-linux","tag-main-c","tag-243","tag-244"],"views":1670,"_links":{"self":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/347","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=347"}],"version-history":[{"count":1,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/347\/revisions"}],"predecessor-version":[{"id":348,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/347\/revisions\/348"}],"wp:attachment":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=347"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=347"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=347"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}