Init进程启动.doc

Init进程启动asmlinkage void _init start_kernel(void).rest_init();static noinline void _init_refok rest_init(void)_releases(kernel_lock)int pid;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);unlock_kernel();/* * 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();static int _init kernel_init(void * unused)/* * Wait until kthreadd is all set-up. */wait_for_completion(&kthreadd_done);lock_kernel();do_basic_setup(); .init_post();return 0;static noinline int init_post(void)_releases(kernel_lock)/* need to finish all async _init code before freeing the memory */async_synchronize_full();free_initmem();unlock_kernel();mark_rodata_ro();system_state = SYSTEM_RUNNING;numa_default_policy();current-signal-flags |= SIGNAL_UNKILLABLE;if (ramdisk_execute_command) run_init_process(ramdisk_execute_command);printk(KERN_WARNING Failed to execute %sn,ramdisk_execute_command);/* * We try each of these until one succeeds. * * The Bourne shell can be used instead of init if we are * trying to recover a really broken machine. */if (execute_command) run_init_process(execute_command);printk(KERN_WARNING Failed to execute %s. Attempting defaults.n, execute_command);run_init_process(/sbin/init);run_init_process(/etc/init);run_init_process(/bin/init);run_init_process(/bin/sh);panic(No init found. Try passing init= option to kernel. See Linux Documentation/init.txt for guidance.);static void run_init_process(char *init_filename)argv_init0 = init_filename;kernel_execve(init_filename, argv_init, envp_init);systemcoreinitinit.cint main(int argc, char *argv) int fd_count = 0; struct pollfd ufds4; char *tmpdev; char* debuggable; char tmp128; int property_set_fd_init = 0; int signal_fd_init = 0; int keychord_fd_init = 0; if (!strcmp(basename(argv0), ueventd) return ueventd_main(argc, argv);int ueventd_main(int argc, char *argv) struct pollfd ufd; int nr; char tmp32; open_devnull_stdio(); log_init(); INFO(starting ueventdn); get_hardware_name(hardware, &revision); ueventd_parse_config_file(/ueventd.rc); snprintf(tmp, sizeof(tmp), /ueventd.%s.rc, hardware); ueventd_parse_config_file(tmp); device_init(); ufd.events = POLLIN; ufd.fd = get_device_fd(); while(1) ufd.revents = 0; nr = poll(&ufd, 1, -1); if (nr = 0) continue; if (ufd.revents = POLLIN) handle_device_fd(); /* clear the umask */umask(0);/创建一些linux根文件系统中的目录，mount一些分区 mkdir(/dev, 0755); mkdir(/proc, 0755); mkdir(/sys, 0755); mount(tmpfs, /dev, tmpfs, 0, 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); /打开标准输入，标准输出，标准错误文件描述符 open_devnull_stdio();/ log 初始化 log_init(); /* initialize array. */ calibration0 = 0;INFO(reading config filen);/读取并且解析init.rc文件init_parse_config_file(/init.rc);int init_parse_config_file(const char *fn) char *data; data = read_file(fn, 0); if (!data) return -1; parse_config(fn, data); DUMP(); return 0;void *read_file(const char *fn, unsigned *_sz) char *data; int sz; int fd; data = 0; fd = open(fn, O_RDONLY); if(fd 0) return 0; sz = lseek(fd, 0, SEEK_END); if(sz 0) goto oops; if(lseek(fd, 0, SEEK_SET) != 0) goto oops; data = (char*) malloc(sz + 2); if(data = 0) goto oops; if(read(fd, data, sz) != sz) goto oops; close(fd); datasz = n; datasz+1 = 0; if(_sz) *_sz = sz; return data;oops: close(fd); if(data != 0) free(data); return 0;static void parse_config(const char *fn, char *s) struct parse_state state; char *argsINIT_PARSER_MAXARGS; int nargs; nargs = 0; state.filename = fn; state.line = 1; state.ptr = s; state.nexttoken = 0; state.parse_line = parse_line_no_op; for (;) switch (next_token(&state) case T_EOF: state.parse_line(&state, 0, 0); return; case T_NEWLINE: if (nargs) int kw = lookup_keyword(args0); if (kw_is(kw, SECTION) state.parse_line(&state, 0, 0); parse_new_section(&state, kw, nargs, args); else state.parse_line(&state, nargs, args); nargs = 0; break; case T_TEXT: if (nargs name, trigger) func(act); void action_add_queue_tail(struct action *act) list_add_tail(&action_queue, &act-qlist); /*把wait_for_coldboot_done_action, property_init_action, keychord_init_action, logo_init_action, console_init_action, set_init_propertyes_action加到action_queue 里*/queue_builtin_action(wait_for_coldboot_done_action, wait_for_coldboot_done);void queue_builtin_action(int (*func)(int nargs, char *args), char *name) struct action *act; struct command *cmd; act = calloc(1, sizeof(*act); act-name = name; list_init(&act-commands); cmd = calloc(1, sizeof(*cmd); cmd-func = func; cmd-args0 = name; list_add_tail(&act-commands, &cmd-clist); list_add_tail(&action_list, &act-alist); action_add_queue_tail(act); queue_builtin_action(property_init_action, property_init); queue_builtin_action(keychord_init_action, keychord_init); queue_builtin_action(console_init_action, console_init); queue_builtin_action(set_init_properties_action, set_init_properties); /触发在init脚本文件中名字为init,early-fs,fs,post-fs的action，并且执行其commandsaction_for_each_trigger(init, action_add_queue_tail); action_for_each_trigger(early-fs, action_add_queue_tail); action_for_each_trigger(fs, action_add_queue_tail); action_for_each_trigger(post-fs, action_add_queue_tail);/*把property_service_init_action, signal_init_action, check_startup_action加到action_queue 里*/ queue_builtin_action(property_service_init_action, property_service_init); queue_builtin_action(signal_init_action, signal_init); queue_builtin_action(check_startup_action, check_startup); /*触发在init脚本文件中名字为early-boot,boot的action，并且执行其commands */ action_for_each_trigger(early-boot, action_add_queue_tail);action_for_each_trigger(boot, action_add_queue_tail);/*把queue_property_triggers_action加到action_queue里*/ queue_builtin_action(queue_property_triggers_action, queue_propety_triggers);#if BOOTCHART queue_builtin_action(bootchart_init_action, bootchart_init);#endifaction触发顺序：early-initinitearly-fsfspost-fsearly-bootboot for(;) int nr, i, timeout = -1; /按序执行action_queue里的action execute_one_command();void execute_one_command(void) int ret; if (!cur_action | !cur_command | is_last_command(cur_action, cur_command) cur_action = action_remove_queue_head(); cur_command = NULL; if (!cur_action) return; INFO(processing action %p (%s)n, cur_action, cur_action-name); cur_command = get_first_command(cur_action); else cur_command = get_next_command(cur_action, cur_command); if (!cur_command) return; ret = cur_command-func(cur_command-nargs, cur_command-args); INFO(command %s r=%dn, cur_command-args0, ret); restart_processes();static void restart_processes() process_needs_restart = 0; service_for_each_flags(SVC_RESTARTING,restart_service_if_needed);void service_for_each_flags(unsigned matchflags, void (*func)(struct service *svc) struct listnode *node; struct service *svc; list_for_each(node, &service_list) svc = node_to_item(node, struct service, slist); if (svc-flags & matchflags) func(svc); static void restart_service_if_needed(struct service *svc) time_t next_start_time = svc-time_started + 5; if (next_start_time flags &= (SVC_RESTARTING); service_start(svc, NULL); return; if (next_start_time 0) ufdsfd_count.fd = get_property_set_fd(); ufdsfd_count.events = POLLIN; ufdsfd_count.revents = 0; fd_count+; property_set_fd_init = 1; if (!signal_fd_init & get_signal_fd() 0) ufdsfd_count.fd = get_signal_fd(); ufdsfd_count.events = POLLIN; ufdsfd_count.revents = 0; fd_count+; signal_fd_init = 1; if (!keychord_fd_init & get_keychord_fd() 0) ufdsfd_count.fd = get_keychord_fd(); ufdsfd_count.events = POLLIN; ufdsfd_count.revents = 0; fd_count+; keychord_fd_init = 1; if (process_needs_restart) timeout = (process_needs_restart - gettime() * 1000; if (timeout 0) if (timeout BOOTCHART_POLLING_MS) timeout = BOOTCHART_POLLING_MS; if (bootchart_step() 0 | -bootchart_count = 0) bootchart_finish(); bootchart_count = 0; #endif /调用poll等待监听事情的发生 nr = poll(ufds, fd_count, timeout); if (nr = 0) continue; for (i = 0; i magic = PROP_AREA_MAGIC; pa-version = PROP_AREA_VERSION; /* plug into the lib property services */ _system_property_area_ = pa; property_area_inited = 1; return 0;3) keychord_init_actionstatic int keychord_init_action(int nargs, char *args) keychord_init(); return 0;void keychord_init() int fd, ret; service_for_each(add_service_keycodes); /* nothing to do if no services require keychords */ if (!keychords) return; fd = open(/dev/keychord, O_RDWR); if (fd = 0) have_console = 1; close(fd); #define INIT_IMAGE_FILE/initlogo.rle if( load_565rle_image(INIT_IMAGE_FILE) ) fd = open(/dev/tty0, O_WRONLY); if (fd = 0) const char *msg; msg = n n n n n n n / console is 40 cols x 30 lines n n n n n n n A N D R O I D ; write(fd, msg, strlen(msg); close(fd); return 0;5) set_init_properties_actionstatic int set_init_properties_action(int nargs, char *args) char tmpPROP_VALUE_MAX; if (qemu0) import_kernel_cmdline(1); if (calibration0) PRINT(#: set ro.calibration 1.n); property_set(ro.calibration, 1); else PRINT(#: set ro.calibration 0.n); property_set(ro.calibration, 0); /* In fastsleep mode. */ if (!strcmp(bootmode,fastsleep) PRINT(#: fastsleep mode.n); PRINT(#: fastsleep mode.n); PRINT(#: fastsleep mode.n); property_set(ro.fastsleep, 1); fastsleep_enable = 1; if (!strcmp(bootmode,factory) property_set(ro.factorytest, 1); else if (!strcmp(bootmode,factory2) property_set(ro.factorytest, 2); else property_set(ro.factorytest, 0); property_set(ro.serialno, serialno0 ? serialno : ); property_set(ro.bootmode, bootmode0 ? bootmode : unknown); property_set(ro.baseband, baseband0 ? baseband : unknown); property_set(ro.carrier, carrier0 ? carrier : unknown); property_set(ro.bootloader, bootloader0 ? bootloader : unknown); property_set(ro.hardware, hardware); snprintf(tmp, PROP_VALUE_MAX, %d, revision); property_set(ro.revision, tmp); return 0;6) property_service_init_actionstatic int property_service_init_action(int nargs, char *args) start_property_service(); return 0;void start_property_service(void) int fd;#define PROP_PATH_RAMDISK_DEFAULT /p#define PROP_PATH_SYSTEM_BUILD /system/p#define PROP_PATH_SYSTEM_DEFAULT /system/p#define PROP_PATH_LOCAL_OVERRIDE /data/p load_properties_from_file(PROP_PATH_SYSTEM_BUILD); load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT); load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE); /* Read persistent properties after all default values have been loaded. */ load_persistent_properties(); fd = create