1. init进程
2. zygote进程
2.1 AndroidRuntime
2.2 ZygoteInit
3. system_server进程
3.1 init1阶段
3.2 init2阶段
接着Linux启动部分 http://blog.csdn.net/qianjin0703/article/details/6881107
1. init进程
系统在内核空间初始化进程,内存,文件系统,驱动模块之后,调用init_post()函数,开启第一个用户进程init,进入用户空间。
/kernel/init/main.c (仅截取部分重要代码)
-
static noinline int init_post(void)
-
{
-
-
run_init_process("/sbin/init");
-
run_init_process("/etc/init");
-
run_init_process("/bin/init");
-
run_init_process("/bin/sh");
-
}
-
static noinline int init_post(void)
-
{
-
-
run_init_process("/sbin/init");
-
run_init_process("/etc/init");
-
run_init_process("/bin/init");
-
run_init_process("/bin/sh");
-
}
终端下查看1号进程,
可见,init是系统守护进程和zygote的父进程。
/system/core/init/init.c
-
int main(int argc, char **argv)
-
{
-
-
mkdir("/dev", 0755);
-
mkdir("/proc", 0755);
-
mkdir("/sys", 0755);
-
-
mount("devpts", "/dev/pts", "devpts", 0, NULL);
-
mount("proc", "/proc", "proc", 0, NULL);
-
mount("sysfs", "/sys", "sysfs", 0, NULL);
-
-
open_devnull_stdio();
-
klog_init();
-
property_init();
-
-
get_hardware_name(hardware, &revision);
-
process_kernel_cmdline();
-
-
init_parse_config_file("/init.rc");
-
action_for_each_trigger("early-init", action_add_queue_tail);
-
-
queue_builtin_action(wait_for_coldboot_done_action, "wait_for_coldboot_done");
-
queue_builtin_action(keychord_init_action, "keychord_init");
-
queue_builtin_action(console_init_action, "console_init");
-
action_for_each_trigger("init", action_add_queue_tail);
-
-
for(;;) {
-
-
execute_one_command();
-
restart_processes();
-
-
nr = poll(ufds, fd_count, timeout);
-
-
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;
-
}
-
int main(int argc, char **argv)
-
{
-
-
mkdir("/dev", 0755);
-
mkdir("/proc", 0755);
-
mkdir("/sys", 0755);
-
-
mount("devpts", "/dev/pts", "devpts", 0, NULL);
-
mount("proc", "/proc", "proc", 0, NULL);
-
mount("sysfs", "/sys", "sysfs", 0, NULL);
-
-
open_devnull_stdio();
-
klog_init();
-
property_init();
-
-
get_hardware_name(hardware, &revision);
-
process_kernel_cmdline();
-
-
init_parse_config_file("/init.rc");
-
action_for_each_trigger("early-init", action_add_queue_tail);
-
-
queue_builtin_action(wait_for_coldboot_done_action, "wait_for_coldboot_done");
-
queue_builtin_action(keychord_init_action, "keychord_init");
-
queue_builtin_action(console_init_action, "console_init");
-
action_for_each_trigger("init", action_add_queue_tail);
-
-
for(;;) {
-
-
execute_one_command();
-
restart_processes();
-
-
nr = poll(ufds, fd_count, timeout);
-
-
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;
-
}
init进程归纳如下
-
解析init.rc和init.*.rc
-
挂载文件系统,建立文件夹和文件,设置权限,为一些文件写入初值
-
初始化property属性
-
启动系统守护进程如adbd, vold, rild等
-
启动zygote进程
2. zygote进程
zygote既是Android系统创建java世界的盘古,又是繁殖system_server和所有应用程序的女娲。
终端下查看zygote进程,
2.1 AndroidRuntime
/frameworks/base/cmds/app_process/app_main.cpp
-
int main(int argc, const char* const argv[])
-
{
-
-
AppRuntime runtime;
-
-
if (zygote) {
-
runtime.start("com.android.internal.os.ZygoteInit",
-
startSystemServer ? "start-system-server" : "");
-
}
-
int main(int argc, const char* const argv[])
-
{
-
-
AppRuntime runtime;
-
-
if (zygote) {
-
runtime.start("com.android.internal.os.ZygoteInit",
-
startSystemServer ? "start-system-server" : "");
-
}
AppRuntime是从AndroidRuntime类派生的,最后由runtime.start()进入Java世界。
/frameworks/base/core/jni/AndroidRuntime.cpp
-
void AndroidRuntime::start(const char* className, const char* options)
-
{
-
-
-
JNIEnv* env;
-
if (startVm(&mJavaVM, &env) != 0) {
-
return;
-
}
-
onVmCreated(env);
-
-
-
-
-
if (startReg(env) < 0) {
-
ALOGE("Unable to register all android natives\n");
-
return;
-
}
-
-
-
-
-
-
char* slashClassName = toSlashClassName(className);
-
jclass startClass = env->FindClass(slashClassName);
-
-
jmethodID startMeth = env->GetStaticMethodID(startClass, "main",
-
"([Ljava/lang/String;)V");
-
-
env->CallStaticVoidMethod(startClass, startMeth, strArray);
-
-
}
-
void AndroidRuntime::start(const char* className, const char* options)
-
{
-
-
-
JNIEnv* env;
-
if (startVm(&mJavaVM, &env) != 0) {
-
return;
-
}
-
onVmCreated(env);
-
-
-
-
-
if (startReg(env) < 0) {
-
ALOGE("Unable to register all android natives\n");
-
return;
-
}
-
-
-
-
-
-
char* slashClassName = toSlashClassName(className);
-
jclass startClass = env->FindClass(slashClassName);
-
-
jmethodID startMeth = env->GetStaticMethodID(startClass, "main",
-
"([Ljava/lang/String;)V");
-
-
env->CallStaticVoidMethod(startClass, startMeth, strArray);
-
-
}
-> 创建虚拟机
注意这里会设置虚拟机的heapsize,默认16M,一般32M,不能太小,否则在操作大尺寸图片时无法分配所需内存。
-> 注册jni函数
这里注册了本地方法,这些方法最终被编译进动态链接库libandroid_runtime.so,供上层Java调用。
-
static const RegJNIRec gRegJNI[] = {
-
REG_JNI(register_android_debug_JNITest),
-
REG_JNI(register_com_android_internal_os_RuntimeInit),
-
REG_JNI(register_android_os_SystemClock),
-
REG_JNI(register_android_util_Log),
-
REG_JNI(register_android_os_Process),
-
REG_JNI(register_android_os_SystemProperties),
-
REG_JNI(register_android_os_Binder),
-
REG_JNI(register_android_view_Display),
-
REG_JNI(register_android_graphics_Bitmap),
-
REG_JNI(register_android_graphics_Camera),
-
REG_JNI(register_android_database_SQLiteDatabase),
-
REG_JNI(register_android_os_Power),
-
REG_JNI(register_android_os_StatFs),
-
REG_JNI(register_android_net_NetworkUtils),
-
REG_JNI(register_android_nfc_NdefMessage),
-
REG_JNI(register_com_android_internal_os_ZygoteInit),
-
REG_JNI(register_android_hardware_Camera),
-
REG_JNI(register_android_hardware_SensorManager),
-
REG_JNI(register_android_hardware_UsbDevice),
-
REG_JNI(register_android_media_AudioRecord),
-
REG_JNI(register_android_media_AudioSystem),
-
REG_JNI(register_android_media_AudioTrack),
-
REG_JNI(register_android_opengl_classes),
-
REG_JNI(register_android_bluetooth_BluetoothSocket),
-
REG_JNI(register_android_server_BluetoothService),
-
-
REG_JNI(register_android_app_ActivityThread),
-
REG_JNI(register_android_app_NativeActivity),
-
REG_JNI(register_android_view_InputChannel),
-
REG_JNI(register_android_view_InputQueue),
-
REG_JNI(register_android_view_KeyEvent),
-
REG_JNI(register_android_view_MotionEvent),
-
REG_JNI(register_android_view_PointerIcon),
-
-
};
-
static const RegJNIRec gRegJNI[] = {
-
REG_JNI(register_android_debug_JNITest),
-
REG_JNI(register_com_android_internal_os_RuntimeInit),
-
REG_JNI(register_android_os_SystemClock),
-
REG_JNI(register_android_util_Log),
-
REG_JNI(register_android_os_Process),
-
REG_JNI(register_android_os_SystemProperties),
-
REG_JNI(register_android_os_Binder),
-
REG_JNI(register_android_view_Display),
-
REG_JNI(register_android_graphics_Bitmap),
-
REG_JNI(register_android_graphics_Camera),
-
REG_JNI(register_android_database_SQLiteDatabase),
-
REG_JNI(register_android_os_Power),
-
REG_JNI(register_android_os_StatFs),
-
REG_JNI(register_android_net_NetworkUtils),
-
REG_JNI(register_android_nfc_NdefMessage),
-
REG_JNI(register_com_android_internal_os_ZygoteInit),
-
REG_JNI(register_android_hardware_Camera),
-
REG_JNI(register_android_hardware_SensorManager),
-
REG_JNI(register_android_hardware_UsbDevice),
-
REG_JNI(register_android_media_AudioRecord),
-
REG_JNI(register_android_media_AudioSystem),
-
REG_JNI(register_android_media_AudioTrack),
-
REG_JNI(register_android_opengl_classes),
-
REG_JNI(register_android_bluetooth_BluetoothSocket),
-
REG_JNI(register_android_server_BluetoothService),
-
-
REG_JNI(register_android_app_ActivityThread),
-
REG_JNI(register_android_app_NativeActivity),
-
REG_JNI(register_android_view_InputChannel),
-
REG_JNI(register_android_view_InputQueue),
-
REG_JNI(register_android_view_KeyEvent),
-
REG_JNI(register_android_view_MotionEvent),
-
REG_JNI(register_android_view_PointerIcon),
-
-
};
2.2 ZygoteInit
/frameworks/base/core/java/com/android/internal/os/ZygoteInit.java
-
public static void main(String argv[]) {
-
try {
-
SamplingProfilerIntegration.start();
-
-
registerZygoteSocket();
-
-
preload();
-
-
SamplingProfilerIntegration.writeZygoteSnapshot();
-
-
if (argv[1].equals("start-system-server")) {
-
startSystemServer();
-
}
-
-
runSelectLoopMode();
-
-
closeServerSocket();
-
}
-
}
-
public static void main(String argv[]) {
-
try {
-
SamplingProfilerIntegration.start();
-
-
registerZygoteSocket();
-
-
preload();
-
-
SamplingProfilerIntegration.writeZygoteSnapshot();
-
-
if (argv[1].equals("start-system-server")) {
-
startSystemServer();
-
}
-
-
runSelectLoopMode();
-
-
closeServerSocket();
-
}
-
}
-> 建立服务端Socket
zygote及系统中其他程序的通信没有使用Binder,而是采用了基于AF_UNIX类型的Socket.
-> 预加载类和资源
预加载的类可以在 /frameworks/base/preloaded-classes 查看。预加载的资源生成framewrok-res.apk,主要是一些图标,刷机达人经常修改它。
-> 启动system_server进程
zygote进程fork出system_server子进程,把任务繁重的系统服务全部托管出去,自己负责循环监听所有应用程序的请求。
-> 等待应用程序的请求
zygote通过runSelectLoopMode()处理应用程序客户端的请求,由ZygoteConnection的runOnce()孵化出新的应用程序。
综上所述,zygote进程归纳如下
-
创建虚拟机
-
注册jni函数
-
预加载类和资源
-
启动system_server进程
-
监听应用程序请求
3. system_server进程
/frameworks/base/services/java/com/android/SystemServer.java
-
public static void main(String[] args) {
-
-
System.loadLibrary("android_servers");
-
init1(args);
-
}
-
public static void main(String[] args) {
-
-
System.loadLibrary("android_servers");
-
init1(args);
-
}
3.1 init1阶段
加载libandriod_server.so库,实现init1
/frameworks/base/cmds/system_server/library/system_init.cpp
-
extern "C" status_t system_init()
-
{
-
-
sp grim = new GrimReaper();
-
sm->asBinder()->linkToDeath(grim, grim.get(), 0);
-
-
char propBuf[PROPERTY_VALUE_MAX];
-
property_get("system_init.startsurfaceflinger", propBuf, "1");
-
if (strcmp(propBuf, "1") == 0) {
-
-
SurfaceFlinger::instantiate();
-
}
-
-
property_get("system_init.startsensorservice", propBuf, "1");
-
if (strcmp(propBuf, "1") == 0) {
-
-
SensorService::instantiate();
-
}
-
-
AndroidRuntime* runtime = AndroidRuntime::getRuntime();
-
-
jclass clazz = env->FindClass("com/android/server/SystemServer");
-
jmethodID methodId = env->GetStaticMethodID(clazz, "init2", "()V");
-
env->CallStaticVoidMethod(clazz, methodId);
-
-
return NO_ERROR;
-
}
-
extern "C" status_t system_init()
-
{
-
-
sp grim = new GrimReaper();
-
sm->asBinder()->linkToDeath(grim, grim.get(), 0);
-
-
char propBuf[PROPERTY_VALUE_MAX];
-
property_get("system_init.startsurfaceflinger", propBuf, "1");
-
if (strcmp(propBuf, "1") == 0) {
-
-
SurfaceFlinger::instantiate();
-
}
-
-
property_get("system_init.startsensorservice", propBuf, "1");
-
if (strcmp(propBuf, "1") == 0) {
-
-
SensorService::instantiate();
-
}
-
-
AndroidRuntime* runtime = AndroidRuntime::getRuntime();
-
-
jclass clazz = env->FindClass("com/android/server/SystemServer");
-
jmethodID methodId = env->GetStaticMethodID(clazz, "init2", "()V");
-
env->CallStaticVoidMethod(clazz, methodId);
-
-
return NO_ERROR;
-
}
3.2 init2阶段
init2回到Java层,启动一个ServerThread线程,启动系统的各项服务。
http://blog.csdn.net/leerobin83/article/details/7306177
阅读(1455) | 评论(0) | 转发(0) |