rk3368 Android9.0 HIDL调试记录

rk3368 Android9.0 HIDL调试记录

Platform: RK3368
OS: Android 9.0
Kernel: 4.4.194

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在Android 8.0以后，低层已重新编写以采用更加模块化的新架构。必须支持使用 HIDL 语言编写的 HAL，下面列出了一些例外情况。这些 HAL 可以是绑定式 HAL 也可以是直通式 HAL.

绑定式 HAL 以 HAL 接口定义语言 (HIDL) 或 Android 接口定义语言 (AIDL) 表示的 HAL。这些 HAL 取代了早期 Android 版本中使用的传统 HAL 和旧版 HAL。在绑定式 HAL 中，Android 框架和 HAL 之间通过 Binder 进程间通信 (IPC) 调用进行通信。所有在推出时即搭载了 Android 8.0 或更高版本的设备都必须只支持绑定式 HAL。

直通式 HAL 以 HIDL 封装的传统 HAL 或旧版 HAL。这些 HAL 封装了现有的 HAL，可在绑定模式和 Same-Process（直通）模式下使用。升级到 Android 8.0 的设备可以使用直通式 HAL。

此调试记录为绑定式 HAL;

1. 使用hidl-gen工具生成接口

1.1 hidl-gen使用方法

$ hidl-gen -h
usage: hidl-gen [-p <root path>] -o <output path> -L <language> [-O <owner>] (-r <interface root>)+ [-v] [-d <depfile>] FQNAME...

Process FQNAME, PACKAGE(.SUBPACKAGE)*@[0-9]+.[0-9]+(::TYPE)?, to create output.

         -h: Prints this menu.
         -L <language>: The following options are available:
            check           : Parses the interface to see if valid but doesn't write any files.
            c++             : (internal) (deprecated) Generates C++ interface files for talking to HIDL interfaces.
            c++-headers     : (internal) Generates C++ headers for interface files for talking to HIDL interfaces.
            c++-sources     : (internal) Generates C++ sources for interface files for talking to HIDL interfaces.
            export-header   : Generates a header file from @export enumerations to help maintain legacy code.
            c++-impl        : Generates boilerplate implementation of a hidl interface in C++ (for convenience).
            c++-impl-headers: c++-impl but headers only
            c++-impl-sources: c++-impl but sources only
            c++-adapter     : Takes a x.(y+n) interface and mocks an x.y interface.
            c++-adapter-headers: c++-adapter but helper headers only
            c++-adapter-sources: c++-adapter but helper sources only
            c++-adapter-main: c++-adapter but the adapter binary source only
            java            : (internal) Generates Java library for talking to HIDL interfaces in Java.
            java-constants  : (internal) Like export-header but for Java (always created by -Lmakefile if @export exists).
            vts             : (internal) Generates vts proto files for use in vtsd.
            makefile        : (removed) Used to generate makefiles for -Ljava and -Ljava-constants.
            androidbp       : (internal) Generates Soong bp files for -Lc++-headers, -Lc++-sources, -Ljava, -Ljava-constants, and -Lc++-adapter.
            androidbp-impl  : Generates boilerplate bp files for implementation created with -Lc++-impl.
            hash            : Prints hashes of interface in `current.txt` format to standard out.
         -O <owner>: The owner of the module for -Landroidbp(-impl)?.
         -o <output path>: Location to output files.
         -p <root path>: Android build root, defaults to $ANDROID_BUILD_TOP or pwd.
         -r <package:path root>: E.g., android.hardware:hardware/interfaces.
         -v: verbose output.
         -d <depfile>: location of depfile to write to.

1.2 创建HIDL文件

1. 新建目录vendor/sample/hardware/interfaces/helloworld/1.0
2. 创建文件: IHelloWorld.hal IHelloWorldCallback.hal types.hal

不要直接在Android源码目录hardware/interfaces下面添加和修改接口,在API锁定分支中不允许更改VNDK库列表.

其中vendor/sample/hardware/interfaces就是hidl的root path了.