在Andorid8.x系統之前，Android系統的服務不是在SystemServer.java中啓動，就在init進程初始化xxx.xxx.rc中啓動。
而Android8.x開始，會發現像/vendor/etc/init/android.hardware.*@2.0-service.rc這種類型的服務和初始化不知道在什麼地方加載起來，本文主要這個這種情況進行分析和優化。
本文轉自：https://blog.csdn.net/touxiong/article/details/80537777
優化開機速度--抓log發現很多用不着的service
[ 22.577559] c3 init: Parsing directory /vendor/etc/init...
[ 22.583263] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.592402] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.603000] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.612471] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.622456] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.631375] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.640973] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.650100] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.659732] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.669427] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.678653] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.689081] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.699269] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.708675] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.718172] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.727480] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.737140] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.746312] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.755606] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.764512] c3 init: Parsing file /vendor/etc/init/[email protected]...
[ 22.773805] c3 init: Parsing file /vendor/etc/init/[email protected]..
想着以前都是在init.rc中把這些腳本import解析執行，搜了一大圈沒找到，又去SystemServer.java中找，也沒找到，回過頭分析log，“Parsing directory” 找到
./core/init/init_parser.cpp: LOG(INFO) << "Parsing directory " << path << "...";
./core/init/init_parser.cpp
bool Parser::ParseConfig(const std::string& path) {
if (is_dir(path.c_str())) {
return ParseConfigDir(path);
}
return ParseConfigFile(path);
}
繼續搜索
std::string bootscript = GetProperty("ro.boot.init_rc", "");
if (bootscript.empty()) {
parser.ParseConfig("/init.rc");
parser.set_is_system_etc_init_loaded(
parser.ParseConfig("/system/etc/init"));
parser.set_is_vendor_etc_init_loaded(
parser.ParseConfig("/vendor/etc/init"));
parser.set_is_odm_etc_init_loaded(parser.ParseConfig("/odm/etc/init"));
} else {
parser.ParseConfig(bootscript);
parser.set_is_system_etc_init_loaded(true);
parser.set_is_vendor_etc_init_loaded(true);
parser.set_is_odm_etc_init_loaded(true);
static void import_late(const std::vector<std::string>& args, size_t start_index, size_t end_index) {
Parser& parser = Parser::GetInstance();
if (end_index <= start_index) {
// Fallbacks for partitions on which early mount isn't enabled.
if (!parser.is_system_etc_init_loaded()) {
parser.ParseConfig("/system/etc/init");
parser.set_is_system_etc_init_loaded(true);
}
if (!parser.is_vendor_etc_init_loaded()) {
parser.ParseConfig("/vendor/etc/init");
parser.set_is_vendor_etc_init_loaded(true);
}
if (!parser.is_odm_etc_init_loaded()) {
parser.ParseConfig("/odm/etc/init");
parser.set_is_odm_etc_init_loaded(true);
}
那請問 /vendor/etc/init 是在上面藍色還是紅色出解析的呢？
接口和軟件包
HIDL 是圍繞接口進行編譯的，接口是面向對象的語言使用的一種用來定義行爲的抽象類型。每個接口都是軟件包的一部分。
軟件包
軟件包名稱可以具有子級，例如 package.subpackage。已發佈的 HIDL 軟件包的根目錄是 hardware/interfaces 或 vendor/vendorName（例如 Pixel 設備爲 vendor/google）。軟件包名稱在根目錄下形成一個或多個子目錄；定義軟件包的所有文件都位於同一目錄下。例如，package [email protected] 可以在 hardware/interfaces/example/extension/light/2.0 下找到。
下表列出了軟件包前綴和位置：
| 軟件包 | 位置 |
| android.hardware.* | hardware/interfaces/* |
| android.frameworks.* | frameworks/hardware/interfaces/* |
| android.system.* | system/hardware/interfaces/* |
| android.hidl.* | system/libhidl/transport/* |
軟件包目錄中包含擴展名爲 .hal 的文件。每個文件均必須包含一個指定文件所屬的軟件包和版本的 package 語句。文件 types.hal（如果存在）並不定義接口，而是定義軟件包中每個接口可以訪問的數據類型.
現在刪除部分serveice:
hidl-gen工具
在Treble架構中，經常會提到HIDL，首先介紹和HIDL相關的一個工具hidl-gen,系統定義的所有的.hal接口，都是通過hidl-gen工具轉換成對應的代碼。比如hardware/interfaces/power/1.0/IPower.hal，會通過hidl-gen轉換成out/soong/.intermediates/hardware/interfaces/power/1.0/[email protected]_genc++/gen/android/hardware/power/1.0/PowerAll.cpp文件，爲了深入瞭解，介紹相關原理,首先分析hidl-gen。
hidl-gen源碼路徑：system/tools/hidl，是在ubuntu上可執行的二進制文件。
使用方法：hidl-gen -o output-path -L language (-r interface-root) fqname
列子：
hidl-gen -Lmakefile -r android.hardware:hardware/interfaces -r android.hidl:system/libhidl/transpor
diff --git a/update-base-files.sh b/update-base-files.sh
index 1eb6b51..b5b1a99 100755
--- a/update-base-files.sh
+++ b/update-base-files.sh
@@ -22,9 +22,9 @@ options="-Lexport-header \
hidl-gen $options \
-o hardware/libhardware/include/hardware/sensors-base.h \
[email protected]
-hidl-gen $options \
- -o hardware/libhardware/include/hardware/nfc-base.h \
- [email protected]
+#hidl-gen $options \
+# -o hardware/libhardware/include/hardware/nfc-base.h \
+# [email protected]
hidl-gen $options \
-o hardware/libhardware/include/hardware/gnss-base.h \
[email protected]
參考：https://source.android.com/devices/architecture/hidl/interfaces