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hal深入剖析之aidl实战-android framework车机车载手机系统开发
2026-11-07 00:02:09
来源：互联网转载
1、创建相关的目录hal目录及aidl存放目录
~/nx563j_xiaomi$ mkdir hardware/interfaces/mytest~/nx563j_xiaomi$ cd hardware/interfaces/mytest/
这个是hal工程根目录
接下来要创建aidl的文件存放目录
test@test:~/nx563j_xiaomi/hardware/interfaces/mytest$ mkdir aidltest@test:~/nx563j_xiaomi/hardware/interfaces/mytest$ cd aidl/test@test:~/nx563j_xiaomi/hardware/interfaces/mytest/aidl$ mkdir -p android/hardware/mytest
注意mkdir -p android/hardware/mytest其实就是包名目录，即模块包名就是android.hardware.mytest.
提示：这个如果为了项目的更加好的维护性建议到自己项目目标的vendor下面进行，目前只是为了演示方便，直接在system的hardware下面
2、创建定义对应aidl文件
创建最重要的aidl接口文件，需要在第一步创建的目录下
test@test:~/nx563j_xiaomi/hardware/interfaces/mytest/aidl/android/hardware/mytest$ touch IMyTest.aidltest@test:~/nx563j_xiaomi/hardware/interfaces/mytest/aidl/android/hardware/mytest$ touch MyTestObj.aidltest@test:~/nx563j_xiaomi/hardware/interfaces/mytest/aidl$ tree.`-- android `-- hardware `-- mytest |-- IMyTest.aidl `-- MyTestObj.aidl
编写aidl内容：
IMyTest.aidl
package android.hardware.mytest; import android.hardware.mytest.MyTestObj; @VintfStability interface IMyTest { MyTestObj test();} MyTestObj.aidl
package android.hardware.mytest; @VintfStability parcelable MyTestObj { String key; int value;} 其实和普通的aidl基本一样，唯一差别就是要多一些稳定性的声明比如@VintfStability这个注解官方解释如下：
VintfStabilityVintfStability declares that a user-defined type (interface, parcelable, and enum) can be used across the system and vendor domains.
还是就是parcelable都是需要进行结构化，成员属性写清楚到aidl
3、编写顶层aidl的Android.bp
最开始的aidl目录创建一个Android.bp
test@test:~/nx563j_xiaomi/hardware/interfaces/mytest/aidl$ touch Android.bp
Android.bp
aidl_interface { name: "android.hardware.mytest", vendor_available: true, srcs: ["android/hardware/mytest/*.aidl"], stability: "vintf", owner:"qianli.ma", backend: { cpp: { enabled: false, }, java: { sdk_version: "module_current", }, },} 需要注意以下几个点：
1、要写aidl_interface目标
2、设置成 vendor_available: true即代表vendor和system都可以用，不是vendor独享
3、stability: “vintf” stability保证接口是稳定的属性，目前只支持vintf
4、backend 这里的后端有4个，C++/JAVA/NDK/RUST, 我们将使用NDK和java，因此将CPP声明为false，为啥不使用c++呢？为啥出来个ndk呢？这个google官方给出了解释
https://source.android.google.cn/docs/core/architecture/aidl/aidl-hals#choosing-runtime
Building against the AIDL runtimeAIDL has three different backends: Java, NDK, CPP. To use Stable AIDL, you must always use the system copy of libbinder at system/lib*/libbinder.so and talk on /dev/binder. For code on the vendor image, this means that libbinder (from the VNDK) cannot be used: this library has an unstable C++ API and unstable internals. Instead, native vendor code must use the NDK backend of AIDL, link against libbinder_ndk (which is backed by system libbinder.so), and link against the -ndk_platform libraries created by aidl_interface entries.
大概意思就是一般aidl的vendor和system跨进程中不使用libbinder的包，因为一般vendor使用是vndk下面的包，故无法访问dev/binder，访问其实是dev/vndbinder,所有一般使用是NDK
4、编译接口文件
编译命令：
test@test:~/nx563j_xiaomi$ mmm hardware/interfaces/mytest
但是出现如下错误
[ 62% 200/319] echo "API dump for the current version of AIDL interface android.hardware.mytest does not exist." && echo Run "m android.hardware.mytest-update-api", or add "unstable: true" to the build rFAILED: out/soong/.intermediates/hardware/interfaces/mytest/aidl/android.hardware.mytest-api/checkapi_current.timestampecho "API dump for the current version of AIDL interface android.hardware.mytest does not exist." && echo Run "m android.hardware.mytest-update-api", or add "unstable: true" to the build rule for the interface if it does not need to be versioned && false # hash of input list: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855API dump for the current version of AIDL interface android.hardware.mytest does not exist.Run m android.hardware.mytest-update-api, or add unstable: true to the build rule for the interface if it does not need to be versioned12:38:45 ninja failed with: exit status 1#### failed to build some targets (01:04 (mm:ss)) ####
大概意思我们的接口是不存在的需要更新api执行：
m android.hardware.mytest-update-api
下面执行新的编译命令：
m android.hardware.mytest-update-api
成功后如下打印
out/soong/Android-lineage_nx563j.mk was modified, regenerating...[100% 190/190] //hardware/interfaces/mytest/aidl:android.hardware.mytest-api Updating AIDL API dump version current for android.hardware.mytest (see hardware/interfaces/mytest/aidl/aidl_api/android.hardw#### build completed successfully (06:57 (mm:ss)) ####
此时的目录已经被生成了aidl_api目录
test@test:~/nx563j_xiaomi/hardware/interfaces/mytest$ tree.`-- aidl |-- Android.bp |-- aidl_api | `-- android.hardware.mytest | `-- current | `-- android | `-- hardware | `-- mytest | |-- IMyTest.aidl | `-- MyTestObj.aidl `-- android `-- hardware `-- mytest |-- IMyTest.aidl `-- MyTestObj.aidl
然后在进行刚才的编译
test@test:~/nx563j_xiaomi$ mmm hardware/interfaces/mytest
成功后会有如下打印
============================================[100% 128/128] Install: out/target/product/nx563j/system/framework/android.hardware.mytest-V1-java.jar#### build completed successfully (03:20 (mm:ss)) ####
这里主要是在编译相关目录生成相关接口代码和库，具体路径如下：
test@test:~/nx563j_xiaomi/out/soong/.intermediates/hardware/interfaces/mytest/aidl$ ls -ltotal 20drwxrwxr-x 3 test test 4096 Dec 12 13:07 android.hardware.mytest-V1-javadrwxrwxr-x 3 test test 4096 Dec 12 13:07 android.hardware.mytest-V1-java-sourcedrwxrwxr-x 16 test test 4096 Dec 12 13:07 android.hardware.mytest-V1-ndkdrwxrwxr-x 3 test test 4096 Dec 12 13:07 android.hardware.mytest-V1-ndk-sourcedrwxrwxr-x 3 test test 4096 Dec 12 13:07 android.hardware.mytest-apitest@test:~/nx563j_xiaomi/out/soong/.intermediates/hardware/interfaces/mytest/aidl$
因为bp中backend只对ndk和java有开放，c++已经关闭了
android.hardware.mytest-V1-ndk 代表aidl相关的库
android.hardware.mytest-V1-ndk-source 代表aidl相关的源文件比如一些头文件或者bp，bn文件
有了上面的生成代码和库，我们就可以写一个服务端的程序了
5、编写服务端程序代码
准备好相关的源文件和xml，rc配置文件
test@test:~/nx563j_xiaomi/hardware/interfaces/mytest/aidl/default$ tree.|-- Android.bp|-- MyTestImpl.cpp|-- MyTestImpl.h|-- android.hardware.mytest.rc|-- main.cpp`-- mytest-default.xml0 directories, 6 files
分为两部分：
源码部分
MyTestImpl.cpp —Binder服务端的具体实现部分cpp
#define LOG_TAG "MyTestImpl"#define LOG_NDEBUG 0#include "MyTestImpl.h"#include #include namespace aidl::android::hardware::mytest { ::ndk::ScopedAStatus MyTestImpl::test(::aidl::android::hardware::mytest::MyTestObj* _aidl_return) { *_aidl_return = mObj; ALOGE(" MyTestImpl::test ok"); return ::ndk::ScopedAStatus::ok();}} // namespace aidl::android::hardware::mytest MyTestImpl.h—Binder服务端的具体实现部分头文件
#ifndef ANDROID_HARDWARE_MYTESTIMPL_H#define ANDROID_HARDWARE_MYTESTIMPL_H#include namespace aidl::android::hardware::mytest {class MyTestImpl : public BnMyTest { public: ::aidl::android::hardware::mytest::MyTestObj mObj = {"hello",1}; ::ndk::ScopedAStatus test(::aidl::android::hardware::mytest::MyTestObj* _aidl_return) override;};} // namespace aidl::android::hardware::mytest#endif main.cpp ----主程序入口cpp
#include "MyTestImpl.h"#define LOG_TAG "MyTestImpl"#define LOG_NDEBUG 0#include #include #include #include #include using aidl::android::hardware::mytest::MyTestImpl;int main() { ABinderProcess_setThreadPoolMaxThreadCount(0); std::shared_ptr test = ::ndk::SharedRefBase::make(); const std::string instance = std::string() + MyTestImpl::descriptor + "/default"; printf("MyTestImpl instance =%s sde =%p \n", instance.c_str(),test->asBinder().get()); binder_status_t status = AServiceManager_addService(test->asBinder().get(), instance.c_str()); CHECK_EQ(status, STATUS_OK); printf("MyTestImpl AServiceManager_addService status=%d \n", status); fflush(stdout); ABinderProcess_joinThreadPool(); return EXIT_FAILURE; // should not reach} bp和配置文件部分
Android.bp --编译可执行文件的bp
cc_binary { name: "android.hardware.mytest.example", relative_install_path: "hw", vendor: true, init_rc: ["android.hardware.mytest.rc"], vintf_fragments: ["mytest-default.xml"], shared_libs: [ "android.hardware.mytest-V1-ndk", "liblog", "libbase", "libcutils", "libutils", "libbinder_ndk", ], srcs: [ "main.cpp", "MyTestImpl.cpp", ],} android.hardware.mytest.rc --开机自启动
service vendor.mytest-default /vendor/bin/hw/android.hardware.mytest.example class hal user root group root
mytest-default.xml ----声明接口到vintf中
android.hardware.mytest 1 IMyTest default
然后再执行编译命令：
mmm hardware/interfaces/mytest/
出现如下成功提示：
aservices============================================[100% 10/10] Install: out/target/product/nx563j/vendor/bin/hw/android.hardware.mytest.example#### build completed successfully (5 seconds) ####
到此基本上aidl业务模块就完成了，一个简单接口实现就好了
6、模块加入到兼容性矩阵中
应该添加到的目录即文件
hardware/interfaces/compatibility_matrices
test@test:~/nx563j_xiaomi/hardware/interfaces/compatibility_matrices$ lltotal 188drwxrwxr-x 4 test test 4096 Dec 12 11:39 ./drwxrwxr-x 54 test test 4096 Dec 12 11:43 ../-rw-rw-r-- 1 test test 2764 Mar 4 2023 Android.bp-rw-rw-r-- 1 test test 4860 Mar 4 2023 Android.mk-rw-rw-r-- 1 test test 2440 Mar 4 2023 CleanSpec.mkdrwxrwxr-x 2 test test 4096 Mar 4 2023 build/-rw-rw-r-- 1 test test 942 Mar 4 2023 clear_vars.mk-rw-rw-r-- 1 test test 15448 Mar 4 2023 compatibility_matrix.3.xml-rw-rw-r-- 1 test test 16709 Mar 4 2023 compatibility_matrix.4.xml-rw-rw-r-- 1 test test 18568 Mar 4 2023 compatibility_matrix.5.xml-rw-rw-r-- 1 test test 21273 Mar 4 2023 compatibility_matrix.6.xml-rw-rw-r-- 1 test test 26116 Dec 12 11:39 compatibility_matrix.7.xml-rw-rw-r-- 1 test test 26380 Dec 12 11:39 compatibility_matrix.current.xml-rw-rw-r-- 1 test test 56 Mar 4 2023 compatibility_matrix.empty.xml-rw-rw-r-- 1 test test 5349 Mar 4 2023 compatibility_matrix.mkdrwxrwxr-x 3 test test 4096 Mar 4 2023 exclude/-rw-rw-r-- 1 test test 41 Mar 4 2023 manifest.empty.xml
这里应该选数字最大的7和current两个xml文件
compatibility_matrix.7.xml
compatibility_matrix.current.xml
2个文件加入如下内容：
android.hardware.mytest 1 IMyTest default
7、增加对应selinux权限
这里直接做成了一个patch方便大家直接apply
到system/sepolicy/然后apply下面这个patch
add-selinux.patch
commit 7b459a68fe188b9f051850ac0629c868a31de2c2Author: Your Name Date: Sun Oct 8 10:03:22 2023 +0800 add selinux for hal mytest Change-Id: I5feeec2aa30cd7fe0d306922225d512c10a0725ediff --git a/prebuilts/api/33.0/private/hwservice_contexts b/prebuilts/api/33.0/private/hwservice_contextsindex 4a44dc58b..8092f0485 100644--- a/prebuilts/api/33.0/private/hwservice_contexts+++ b/prebuilts/api/33.0/private/hwservice_contexts@@ -6,6 +6,7 @@ android.frameworks.schedulerservice::ISchedulingPolicyService u:object_r:fwk_s android.frameworks.sensorservice::ISensorManager u:object_r:fwk_sensor_hwservice:s0 android.frameworks.stats::IStats u:object_r:fwk_stats_hwservice:s0 android.hardware.atrace::IAtraceDevice u:object_r:hal_atrace_hwservice:s0+android.hardware.mytest::IMyTest u:object_r:hal_mytest_hwservice:s0 android.hardware.audio.effect::IEffectsFactory u:object_r:hal_audio_hwservice:s0 android.hardware.audio::IDevicesFactory u:object_r:hal_audio_hwservice:s0 android.hardware.authsecret::IAuthSecret u:object_r:hal_authsecret_hwservice:s0diff --git a/prebuilts/api/33.0/private/service_contexts b/prebuilts/api/33.0/private/service_contextsindex 72fa16629..936638f18 100644--- a/prebuilts/api/33.0/private/service_contexts+++ b/prebuilts/api/33.0/private/service_contexts@@ -15,6 +15,7 @@ android.hardware.contexthub.IContextHub/default u:object_r: android.hardware.drm.IDrmFactory/clearkey u:object_r:hal_drm_service:s0 android.hardware.drm.ICryptoFactory/clearkey u:object_r:hal_drm_service:s0 android.hardware.dumpstate.IDumpstateDevice/default u:object_r:hal_dumpstate_service:s0+android.hardware.mytest.IMyTest/default u:object_r:hal_mytest_service:s0 android.hardware.gnss.IGnss/default u:object_r:hal_gnss_service:s0 android.hardware.graphics.allocator.IAllocator/default u:object_r:hal_graphics_allocator_service:s0 android.hardware.graphics.composer3.IComposer/default u:object_r:hal_graphics_composer_service:s0diff --git a/private/hwservice_contexts b/private/hwservice_contextsindex 4a44dc58b..8092f0485 100644--- a/private/hwservice_contexts+++ b/private/hwservice_contexts@@ -6,6 +6,7 @@ android.frameworks.schedulerservice::ISchedulingPolicyService u:object_r:fwk_s android.frameworks.sensorservice::ISensorManager u:object_r:fwk_sensor_hwservice:s0 android.frameworks.stats::IStats u:object_r:fwk_stats_hwservice:s0 android.hardware.atrace::IAtraceDevice u:object_r:hal_atrace_hwservice:s0+android.hardware.mytest::IMyTest u:object_r:hal_mytest_hwservice:s0 android.hardware.audio.effect::IEffectsFactory u:object_r:hal_audio_hwservice:s0 android.hardware.audio::IDevicesFactory u:object_r:hal_audio_hwservice:s0 android.hardware.authsecret::IAuthSecret u:object_r:hal_authsecret_hwservice:s0diff --git a/private/service_contexts b/private/service_contextsindex 72fa16629..936638f18 100644--- a/private/service_contexts+++ b/private/service_contexts@@ -15,6 +15,7 @@ android.hardware.contexthub.IContextHub/default u:object_r: android.hardware.drm.IDrmFactory/clearkey u:object_r:hal_drm_service:s0 android.hardware.drm.ICryptoFactory/clearkey u:object_r:hal_drm_service:s0 android.hardware.dumpstate.IDumpstateDevice/default u:object_r:hal_dumpstate_service:s0+android.hardware.mytest.IMyTest/default u:object_r:hal_mytest_service:s0 android.hardware.gnss.IGnss/default u:object_r:hal_gnss_service:s0 android.hardware.graphics.allocator.IAllocator/default u:object_r:hal_graphics_allocator_service:s0 android.hardware.graphics.composer3.IComposer/default u:object_r:hal_graphics_composer_service:s0diff --git a/vendor/file_contexts b/vendor/file_contextsindex 392a750fd..b87914600 100644--- a/vendor/file_contexts+++ b/vendor/file_contexts@@ -105,6 +105,7 @@ /(vendor|system/vendor)/bin/hw/wpa_supplicant u:object_r:hal_wifi_supplicant_default_exec:s0 /(vendor|system/vendor)/bin/install-recovery\.sh u:object_r:vendor_install_recovery_exec:s0 /(vendor|system/vendor)/bin/vndservicemanager u:object_r:vndservicemanager_exec:s0+/(vendor|system/vendor)/bin/hw/android\.hardware\.mytest\.example u:object_r:hal_mytest_default_exec:s0 ############################# # Same process HALs installed by platform into /vendordiff --git a/vendor/hal-aidl-mytest.te b/vendor/hal-aidl-mytest.tenew file mode 100644index 000000000..378df3826--- /dev/null+++ b/vendor/hal-aidl-mytest.te@@ -0,0 +1,39 @@+# type hal_mytest, domain;+# type hal_mytest_service, vendor_service, service_manager_type;+# type hal_mytest_hwservice, hwservice_manager_type, protected_hwservice;+# type hal_mytest_default_exec, exec_type, vendor_file_type, file_type;+# init_daemon_domain(hal_mytest);++++# get_prop(hal_mytest, hwservicemanager_prop)+# add_hwservice(hal_mytest, hal_mytest_hwservice)+# hwbinder_use(hal_mytest);+++# allow platform_app hal_mytest_hwservice:hwservice_manager { find };+# allow platform_app hal_mytest:binder {call};+++hal_attribute(mytest);+type hal_mytest_default, domain, mlstrustedsubject;+hal_server_domain(hal_mytest_default, hal_mytest);+type hal_mytest_default_exec, exec_type, vendor_file_type, file_type;+init_daemon_domain(hal_mytest_default);++#Allow hwbinder call form hal client to server+binder_call(hal_mytest_client, hal_mytest_default_exec)++#add hwservice related rules+type hal_mytest_service, vendor_service, service_manager_type;+type hal_mytest_hwservice, hwservice_manager_type, protected_hwservice;+get_prop(hal_mytest, hwservicemanager_prop)+add_service(hal_mytest_default, hal_mytest_service)+add_hwservice(hal_mytest_server, hal_mytest_hwservice)+allow hal_mytest_client hal_mytest_hwservice:hwservice_manager find;+hal_client_domain(system_server, hal_mytest)+hwbinder_use(hal_mytest);++allow hal_mytest_default servicemanager:binder { call transfer };+allow { platform_app shell } hal_mytest_hwservice:hwservice_manager { find };+allow { platform_app shell } hal_mytest:binder {call}; 8、编写一个测试模块，来测试一下aidl的hal是否正常运行
aidl目录下创建一个test_hal目录：
test_hal/|-- Android.bp`-- main.cpp
Android.bp
cc_binary { name: "test-hal-mytest", shared_libs: [ "android.hardware.mytest-V1-ndk", "liblog", "libbase", "libcutils", "libutils", "libbinder_ndk", ], srcs: [ "main.cpp", ],} 主要就是需要引入 “android.hardware.mytest-V1-ndk”, 这个依赖库
main.cpp
#define LOG_TAG "Test-HAL"#define LOG_NDEBUG 0#include #include #include #include #include #include using aidl::android::hardware::mytest::IMyTest;int main() { printf("test hal mytest main 1\n"); std::shared_ptr service = IMyTest::fromBinder(ndk::SpAIBinder(AServiceManager_getService("android.hardware.mytest.IMyTest/default"))); printf("test hal mytest service = %p\n",service.get()); ALOGE("Test hal MyTest"); if (service == nullptr) { return -1; } ::aidl::android::hardware::mytest::MyTestObj obj; service->test(&obj); printf("test hal mytest main test result %s %d \n",obj.key.c_str(),obj.value); fflush(stdout); return EXIT_FAILURE; // should not reach} 9、device下面加入相关的程序进入编译到整机
device/nubia/nx563j/device.mk文件中加入如下：
PRODUCT_PACKAGES += \ android.hardware.mytest \ android.hardware.mytest.example \ test-hal-mytest \
10、测试部分
测试方法
1、先看看是否mytest的hal服务是否开机自启动了
2、执行test-hal-mytest看看是否输出正常
本文章对应视频手把手教你学framework：
https://mp.weixin.qq.com/s/LbVLnu1udqExHVKxd74ILg
私聊作者+v(androidframework007)
点击这里 https://mp.weixin.qq.com/s/Qv8zjgQ0CkalKmvi8tMGaw
视频：https://www.bilibili.com/video/BV1wc41117L4/
