i.mx6 Android5.1.1 初始化流程之init进程(未完成)

概述:

 

接在i.mx6 Android5.1.1 初始化流程之框架之后

参考资料:http://blog.csdn.net/mr_raptor/article/category/799879

相关源码:  /system/core/init/

相关配置文件:/system/core/rootdir/

 

从下面全文可以得出:

1).init进程和其相关的文件init.rc、ueventd.rc是在ramdisk.img中

2).修改节点权限:  /ueventd.rc   /ueventd.Freescale.rc

3). 修改相关服务和创建文件:/init.rc  

 

1. mian.c

关于代码中的属性服务,可以查看:i.mx6 Android5.1.1 系统属性   

关于代码中的init.rc,可以查看:      i.mx6 Android5.1.1 初始化流程之init.rc解析

int main(int argc, char **argv)
{
    int fd_count = 0;
    struct pollfd ufds[4];
    char *tmpdev;
    char* debuggable;
    char tmp[32];
    int property_set_fd_init = 0;
    int signal_fd_init = 0;
    int keychord_fd_init = 0;
    bool is_charger = false;
    char watchdog[PROPERTY_MAX_VALUE];
    int ret;
    
  /*后面两个是初始化ueventd和看门狗,从上一章的ps中可以看出,这两个确实是进程init(PID=1)最初创建的两个进程*/
  /*查看是否有看门狗的属性*/ ret
= property_get("ro.boot.watchdogd", watchdog);
  /*启动ueventd进程*/
if (!strcmp(basename(argv[0]), "ueventd")) return ueventd_main(argc, argv);    if (!strcmp(basename(argv[0]), "watchdogd")) { if(ret && !(strcmp(watchdog, "disabled"))) { return 0; } else { return watchdogd_main(argc, argv); /*在这里启动看门狗*/ } } /* clear the umask */ umask(0); /* Get the basic filesystem setup we need put * together in the initramdisk on / and then we'll * let the rc file figure out the rest. */

  /* 创建目录,挂在文件系统,给权限
   * tmpfs :/dev

   * devpts :/dev/pts
   * proc :/proc  
   * sysfs :/sys
   */ mkdir(
"/dev", 0755); mkdir("/proc", 0755); mkdir("/sys", 0755); mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755"); mkdir("/dev/pts", 0755); mkdir("/dev/socket", 0755); mount("devpts", "/dev/pts", "devpts", 0, NULL); mount("proc", "/proc", "proc", 0, NULL); mount("sysfs", "/sys", "sysfs", 0, NULL); close(open("/dev/.booting", O_WRONLY | O_CREAT, 0000)); open_devnull_stdio(); //将标准输入、输出、错误定向到空 klog_init();     //将log重定向到/proc/kmsg当中 property_init(); //初始化属性服务,关于属性服务,可以查看:i.mx6 Android5.1.1 系统属性 get_hardware_name(hardware, &revision); //得到硬件信息和版本信息 get_soc_name(soc); //得到soc名字 process_kernel_cmdline(); // 设置基本属性 union selinux_callback cb; cb.func_log = log_callback; selinux_set_callback(SELINUX_CB_LOG, cb); cb.func_audit = audit_callback; selinux_set_callback(SELINUX_CB_AUDIT, cb); selinux_initialize(); /* These directories were necessarily created before initial policy load * and therefore need their security context restored to the proper value. * This must happen before /dev is populated by ueventd. */ restorecon("/dev"); restorecon("/dev/socket"); restorecon("/dev/__properties__"); restorecon_recursive("/sys"); is_charger = !strcmp(bootmode, "charger"); INFO("property init\n"); property_load_boot_defaults(); //加载/default.prop文件 进行默认属性配置相关的工作 INFO("reading config file\n"); init_parse_config_file("/init.rc"); //注意:解析/init.rc,并将所有元素加入链表,关于init.rc,可以查看:i.mx6 Android5.1.1 系统属性 

  /* 首先说明一下,在函数中对于init.rc命令的解析之后,将所有命令分类分别挂在了action_list,service_list,action_queue三个链表当中
   *
serevice_list:用于保存init.rc当中的service配置信息
   * action_list: 用于保存从init.rc当中解析出来的所有action
   * action_queue: 用于保存所有待执行的action
   *
   * 下面的两个函数action_for_each_trigger和queue_builtin_action

   * action_for_each_trigger:将action加入到action_queue当中,表示正准备执行
   * queue_builtin_action: 创建一个action,并将其挂在atcion_queue和action_list当中,
   */
    action_for_each_trigger("early-init", action_add_queue_tail); //接着上面,把链表中为on early-init的元素提取执行。(我们没有)将early-init动作添加到链表action_queue中   
    
    queue_builtin_action(wait_for_coldboot_done_action, "wait_for_coldboot_done"); //创建wait_for_coldboot_done动作并添加到链表action_queue和action_list中,在这里注意action_list用于保存从init.rc中解析出来的所有Action,而action_queue却是用于保存待执行的Action,action_queue是一个待执行队列。
 
    queue_builtin_action(mix_hwrng_into_linux_rng_action, "mix_hwrng_into_linux_rng");
    queue_builtin_action(keychord_init_action, "keychord_init");
    queue_builtin_action(console_init_action, "console_init");

    /* execute all the boot actions to get us started */
    action_for_each_trigger("init", action_add_queue_tail);//执行Init.rc中的on init(这个我们就有了),后面分析

    /* Repeat mix_hwrng_into_linux_rng in case /dev/hw_random or /dev/random
     * wasn't ready immediately after wait_for_coldboot_done
     */
    queue_builtin_action(mix_hwrng_into_linux_rng_action, "mix_hwrng_into_linux_rng");
    queue_builtin_action(property_service_init_action, "property_service_init");
    queue_builtin_action(signal_init_action, "signal_init");

    /* Don't mount filesystems or start core system services if in charger mode. */
    if (is_charger) {
        action_for_each_trigger("charger", action_add_queue_tail); //执行这个,不执行下面的
    } else {
        action_for_each_trigger("late-init", action_add_queue_tail);
    }

    /* run all property triggers based on current state of the properties */
    queue_builtin_action(queue_property_triggers_action, "queue_property_triggers");


#if BOOTCHART
    queue_builtin_action(bootchart_init_action, "bootchart_init");
#endif
  
    for(;;) {
        int nr, i, timeout = -1;

        execute_one_command();  //按序执行action_queue里的action
        restart_processes();    //重启一些关键进程,也就是守护进程
        //添加,只执行一次
        if (!property_set_fd_init && get_property_set_fd() > 0) {
            ufds[fd_count].fd = get_property_set_fd();
            ufds[fd_count].events = POLLIN;
            ufds[fd_count].revents = 0;
            fd_count++;
            property_set_fd_init = 1;
        }
     /*同上*/
if (!signal_fd_init && get_signal_fd() > 0) { ufds[fd_count].fd = get_signal_fd(); ufds[fd_count].events = POLLIN; ufds[fd_count].revents = 0; fd_count++; signal_fd_init = 1; }
     /*同上*/
if (!keychord_fd_init && get_keychord_fd() > 0) { ufds[fd_count].fd = get_keychord_fd(); ufds[fd_count].events = POLLIN; ufds[fd_count].revents = 0; fd_count++; keychord_fd_init = 1; } //计算超时时间 if (process_needs_restart) { timeout = (process_needs_restart - gettime()) * 1000; if (timeout < 0) timeout = 0; } if (!action_queue_empty() || cur_action) timeout = 0; #if BOOTCHART if (bootchart_count > 0) { if (timeout < 0 || timeout > BOOTCHART_POLLING_MS) timeout = BOOTCHART_POLLING_MS; if (bootchart_step() < 0 || --bootchart_count == 0) { bootchart_finish(); bootchart_count = 0; } } #endif //监控句柄池中的事件,如果都没有变化,程序就停在这里了 nr = poll(ufds, fd_count, timeout); if (nr <= 0) continue; //对于监听到的事件进行处理 for (i = 0; i < fd_count; i++) { if (ufds[i].revents & POLLIN) { if (ufds[i].fd == get_property_set_fd()) handle_property_set_fd(); else if (ufds[i].fd == get_keychord_fd()) handle_keychord(); else if (ufds[i].fd == get_signal_fd()) handle_signal(); } } } return 0; }

 

小结:

1。启动ueventd和watchdogd进程

2。将标准输入,输出,错误定向到null

3.重定向log

4.初始化属性的区域

5.添加各种属性

6.解析init.rc

7.将init.rc中解析出来的行为进行分类保存,并再添加一些默认行为

8.进入循环守护

  1). 执行action_queue中的action

  2). 守护一些关键进程

  3). 建立属性、信号、组合按键的监听。当有行为发生时,对其进行相应处理,没有则停滞在这里 

 

 

从上诉程序可以分析出action的执行顺序为:

early-init                   ------------------>>init.rc
wait_for_coldboot_done
mix_hwrng_into_linux_rng
keychord_init
console_init
init         ------------------>>init.rc
mix_hwrng_into_linux_rng
property_service_init
signal_init
charger或者late-init  ------------------>>init.rc
queue_property_triggers

 

2. ueventd_main

int ueventd_main(int argc, char **argv)
{
    struct pollfd ufd;
    int nr;
    char tmp[32];

    /*
     * init sets the umask to 077 for forked processes. We need to
     * create files with exact permissions, without modification by
     * the umask.
     */
    umask(000);

    /* Prevent fire-and-forget children from becoming zombies.
     * If we should need to wait() for some children in the future
     * (as opposed to none right now), double-forking here instead
     * of ignoring SIGCHLD may be the better solution.
     */
    signal(SIGCHLD, SIG_IGN);

    open_devnull_stdio();
    klog_init();
#if LOG_UEVENTS
    /* Ensure we're at a logging level that will show the events */
    if (klog_get_level() < KLOG_INFO_LEVEL) {
        klog_set_level(KLOG_INFO_LEVEL);
    }
#endif

    union selinux_callback cb;
    cb.func_log = log_callback;
    selinux_set_callback(SELINUX_CB_LOG, cb);

    INFO("starting ueventd\n");

    /* Respect hardware passed in through the kernel cmd line. Here we will look
     * for androidboot.hardware param in kernel cmdline, and save its value in
     * hardware[]. */
    import_kernel_cmdline(0, import_kernel_nv);

    get_hardware_name(hardware, &revision);
    //解析ueventd.rc和ueventd.fressale.rc
    ueventd_parse_config_file("/ueventd.rc");

    snprintf(tmp, sizeof(tmp), "/ueventd.%s.rc", hardware);
    ueventd_parse_config_file(tmp);
    //设备初始化
    device_init();

    ufd.events = POLLIN;
    ufd.fd = get_device_fd();

    while(1) {
        ufd.revents = 0;
        nr = poll(&ufd, 1, -1);    //循环等待
        if (nr <= 0)
            continue;
        if (ufd.revents & POLLIN)
               handle_device_fd();  //讲接收过来的信息进行处理
    }
}

 

 

 

 

往下查看 i.mx6 Android5.1.1 初始化流程之init.rc解析

 

posted on 2017-10-13 14:42  maogefff  阅读(557)  评论(0编辑  收藏  举报

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