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53 lines
984 B
53 lines
984 B
5 years ago
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---
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应用是怎么启用 binder 机制的？
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---
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1. 了解 binder 是用来干嘛的？
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2. 应用里面哪些地方用到了 binder 机制？
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3. 应用的大致启动流程是怎样的？
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4. 一个进程是怎么启用 binder 机制的？
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#### 什么时候支持 binder 机制的？
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#### binder 启动时机
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```java
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// handleChildProc(...)
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static void zygoteInit() {
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commonInit();
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nativeZygoteInit();
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applicationInit(...);
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}
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```
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```c
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void nativeZygoteInit(...) {
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gCurRuntime->onZygoteInit();
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}
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```
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```c
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virtual void onZygoteInit() {
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sp<ProcessState> proc = ProcessState::self();
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proc->startThreadPool();
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}
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```
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```c
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ProcessState::ProcessState()
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// open_driver() 打开 "/dev/binder" 驱动
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:mDriverFD(open_driver()), ... {
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if(mDriverFD>=0) {
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mVMStart = mmap(0, BINDER_VM_SIZE, PROT_READ, ..., mDriverFD, 0);
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}
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}
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```
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#### 怎么启用 Binder 机制？
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1. 打开 binder 驱动
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2. 映射内存，分配缓冲区
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3. 注册 binder 线程
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4. 进入 binder loop
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