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diff --git a/en/devices/architecture/configstore/service.html b/en/devices/architecture/configstore/service.html new file mode 100644 index 00000000..09874b4d --- /dev/null +++ b/en/devices/architecture/configstore/service.html @@ -0,0 +1,128 @@ +<html devsite> + <head> + <title>Implementing the Service</title> + <meta name="project_path" value="/_project.yaml" /> + <meta name="book_path" value="/_book.yaml" /> + </head> + <body> + <!-- + Copyright 2017 The Android Open Source Project + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + --> + +<p>To prepare for the HAL implementation, you can generate basic configstore +interface code then modify it to meet your needs.</p> + +<h2 id=generate-boilerplate>Generating interface code</h2> +<p>To generate boilerplate code for the interface, run <code>hidl-gen</code>. +For example, to generate code for <code>surfaceflinger</code>:</p> + +<pre class="devsite-terminal devsite-click-to-copy"> +hidl-gen -o hardware/interfaces/configstore/1.0/default \ + -Lc++-impl \ + -randroid.hardware:hardware/interfaces \ + -randroid.hidl:system/libhidl/transport \ + android.hardware.config@1.0::ISurfaceFlingerConfigs +</pre> + +<p class="note"><strong>Note:</strong> Don't run <code>hidl-gen</code> with +<code>-Landroidbp-impl</code> as this generates <code>Android.bp</code>. The +module must be built with <code>Android.mk</code> to access build flags.</p> + +<h2 id=modify-androidmk>Modifying Android.mk</h2> +<p>Next, modify <code>Android.mk</code> file to add implementation file +(<code><modulename>Configs.cpp</code>) to <code>LOCAL_SRC_FILES</code> and +to map build flags into macro definitions. For example, you can modify +<code>surfaceflinger</code> in +<strong><code>hardware/interface/configstore/1.0/default/Android.mk</code></strong>: +</p> + +<pre class="devsite-click-to-copy"> +LOCAL_SRC_FILES += SurfaceFlingerConfigs.cpp +ifneq ($(NUM_FRAMEBUFFER_SURFACE_BUFFERS),) + LOCAL_CFLAGS += -DNUM_FRAMEBUFFER_SURFACE_BUFFERS=$(NUM_FRAMEBUFFER_SURFACE_BUFFERS) +endif + +ifeq ($(TARGET_RUNNING_WITHOUT_SYNC_FRAMEWORK),true) + LOCAL_CFLAGS += -DRUNNING_WITHOUT_SYNC_FRAMEWORK +endif +</pre> + +<p>If <code>Android.mk</code> includes several <code>ifeq-endif</code> blocks, +consider moving your code into a new file (i.e., <code>surfaceflinger.mk</code>) +then include that file from <code>Android.mk</code>.</p> + +<h2 id=implement-functions>Implementing functions</h2> +<p>To fill the functions to implement the HAL, call back the +<code>_hidl_cb</code> function with different values (conditioned on build +flags). For example, you can fill the functions for <code>surfaceflinger</code> +in <strong><code>hardware/interfaces/configstore/1.0/default/SurfaceFlingerConfigs.cpp</code></strong>:</p> + +<pre class="devsite-click-to-copy"> +Return<void> SurfaceFlingerConfigs::numFramebufferSurfaceBuffers( + numFramebufferSurfaceBuffers_cb _hidl_cb) { + #if NUM_FRAMEBUFFER_SURFACE_BUFFERS 2 + _hidl_cb(NumBuffers.TWO); + #else if NUM_FRAMEBUFFER_SURFACE_BUFFERS 3 + _hidl_cb(NumBuffers.THREE); + #else + _hidl_cb(NumBuffers.USE_DEFAULT); + #endif +} + +Return<void> SurfaceFlingerConfigs::runWithoutSyncFramework( + runWithoutSyncFramework_cb _hidl_cb) { + #ifdef RUNNING_WITHOUT_SYNC_FRAMEWORK + _hidl_cb({true /* specified */, true /* value */}); + #else + // when macro not defined, we can give any value to the second argument. + // It will simply be ignored in the framework side. + _hidl_cb({false /* specified */, false /* value */}); + #endif +} +</pre> + +<p>Ensure the implementation does not contain a function named +<code>HIDL_FETCH_<interface name></code> (e.g., +<code>HIDL_FETCH_ISurfaceFlingerConfigs</code>). This function is needed for +HIDL passthrough mode, which is unused (and prohibited) by +<code>configstore</code>. ConfigStore must always run in binderized mode.</p> + +<h2 id=register-service>Registering as a service</h2> +<p>Finally, register all interface implementations to the +<code>configstore</code> service. For example, you can register +<code>surfaceflinger</code> implementations in +<strong><code>hardware/interfaces/configstore/1.0/default/service.cpp</code></strong>: +</p> + +<pre class="devsite-click-to-copy"> +configureRpcThreadpool(maxThreads, true); +sp<ISurfaceFlingerConfigs> surfaceFlingerConfigs = new SurfaceFlingerConfigs; +status_t status = surfaceFlingerConfigs->registerAsService(); + +sp<IBluetoothConfigs> bluetoothConfigs = new BluetoothConfigs; +status = bluetoothConfigs->registerAsService(); + +// register more interfaces here +joinRpcThreadpool(); +</pre> + +<h2 id=bootstrapping>Ensuring early access</h2> +<p>To ensure a framework module can get early access the HAL service, the config +HAL service should start as early as possible, just after +<code>hwservicemanager</code> is ready. As the config HAL service does not read +external files, it is expected to be ready quickly after it is launched.</p> + + </body> +</html> |