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开机过程关键日志记录和介绍

news 2026/8/7 22:58:31

前言

开机阶段描述

先用命令:

adb logcat -b events|grep boot

过滤出启动阶段的主要事件。可以看到关键log基本把开机的每一步都打印了出来

01-01 08:00:18.096 591 591 I boot_progress_start: 12229 01-01 08:00:19.291 591 591 I boot_progress_preload_start: 13425 01-01 08:00:21.902 591 591 I boot_progress_preload_end: 16035 01-01 08:00:22.196 1504 1504 I boot_progress_system_run: 16330 01-01 08:00:22.817 1504 1504 I boot_progress_pms_start: 16950 01-01 08:00:23.189 1504 1504 I boot_progress_pms_system_scan_start: 17322 01-01 08:00:25.347 1504 1504 I boot_progress_pms_data_scan_start: 19480 01-01 08:00:25.462 1504 1504 I boot_progress_pms_scan_end: 19595 01-01 08:00:25.626 1504 1504 I boot_progress_pms_ready: 19759 05-08 18:46:58.709 1504 1504 I boot_progress_ams_ready: 20802 05-08 18:47:00.093 1504 1632 I boot_progress_enable_screen: 22187 05-08 18:47:01.931 742 2191 I sf_stop_bootanim: 24024 05-08 18:47:01.934 1504 1632 I wm_boot_animation_done: 24027

阶段	描述
boot_progress_start	系统进入用户空间，标志着kernel启动完成
boot_progress_preload_start	Zygote启动
boot_progress_preload_end	Zygote结束
boot_progress_system_run	SystemServer ready,开始启动Android系统服务
boot_progress_pms_start	PMS开始扫描安装的应用
boot_progress_pms_system_scan_start	PMS先行扫描/system目录下的安装包
boot_progress_pms_data_scan_start	PMS扫描/data目录下的安装包
boot_progress_pms_scan_end	PMS扫描结束
boot_progress_pms_ready	PMS就绪
boot_progress_ams_ready	AMS就绪
boot_progress_enable_screen	AMS启动完成后开始激活屏幕，从此以后屏幕才能响应用户的触摸，它在WindowManagerService发出退出开机动画的时间节点之前
sf_stop_bootanim	SF设置service.bootanim.exit属性值为1，标志系统要结束开机动画了
wm_boot_animation_done	开机动画结束，这一步用户能直观感受到开机结束

一.各个阶段对应的代码

1. boot_progress_start

frameworks/base/core/jni/AndroidRuntime.cpp

void AndroidRuntime::start(const char* className, const Vector<String8>& options, bool zygote)
{
...
/*
* 'startSystemServer == true' means runtime is obsolete and not run from
* init.rc anymore, so we print out the boot start event here.
*/
for (size_t i = 0; i < options.size(); ++i) {
if (options[i] ==startSystemServer) {
primary_zygote = true;
/* track our progress through the boot sequence */
const intLOG_BOOT_PROGRESS_START= 3000;
//日志打印
LOG_EVENT_LONG(LOG_BOOT_PROGRESS_START, ns2ms(systemTime(SYSTEM_TIME_MONOTONIC)));
}
}
...
}

对应的

3000boot_progress_start (time|2|3)

2. boot_progress_preload_start

3. boot_progress_preload_end

/frameworks/base/core/java/com/android/internal/os/ZygoteInit.java

private static final intLOG_BOOT_PROGRESS_PRELOAD_START= 3020;
private static final intLOG_BOOT_PROGRESS_PRELOAD_END= 3030;
public static void main(String[] argv) {
...
// In some configurations, we avoid preloading resources and classes eagerly.
// In such cases, we will preload things prior to our first fork.
if (!enableLazyPreload) {
bootTimingsTraceLog.traceBegin("ZygotePreload");
EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_START,SystemClock.uptimeMillis());
preload(bootTimingsTraceLog); //输出日志
EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_END, SystemClock.uptimeMillis());
bootTimingsTraceLog.traceEnd(); // ZygotePreload
}
// Do an initial gc to clean up after startup
bootTimingsTraceLog.traceBegin("PostZygoteInitGC");
gcAndFinalize();
bootTimingsTraceLog.traceEnd(); // PostZygoteInitGC
bootTimingsTraceLog.traceEnd(); // ZygoteInit
Zygote.initNativeState(isPrimaryZygote);
/// M: Added for BOOTPROF
addBootEvent("Zygote:Preload End");
...
}

system/logging/logcat/event.logtags

# ZygoteInit class preloading starts:3020boot_progress_preload_start (time|2|3) # ZygoteInit class preloading ends:3030boot_progress_preload_end (time|2|3)