Android12 Gralloc_gralloc4allocator-优快云博客

软件环境：ubuntu20.04 aosp
硬件环境：X86 PC
模拟环境：在host ubuntu20.04启动支持图形(by virtio-gpu)的Android虚拟机

1. 概述

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2. Android12 Gralloc

2.1 接口说明

gralloc主要提供IAllocator和IMapper两类接口

#gralloc HAL接口定义：IAllocator
/hardware/interfaces/graphics/allocator/4.0/IAllocator.hal
#mapper HAL接口定义：IMapper
/hardware/interfaces/graphics/mapper/4.0/IMapper.hal

2.2 实现说明

gralloc有多种实现，如mali，msm，nxp，goldfish，minigbm等

 #ID和版本
GRALLOC_HARDWARE_MODULE_ID
GRALLOC_MODULE_API_VERSION_1_0 //msm nxp
GRALLOC_MODULE_API_VERSION_0_3 //minigbm-gralloc0 hikey960
GRALLOC_MODULE_API_VERSION_0_2 //goldfish-gralloc30 hikey960

#头文件和实现
hardware/libhardware/include/hardware
libhardware/modules/gralloc/gralloc.cpp

二进制

#厂商实现库位于vendor/lib64/hw
libminigbm_gralloc.so

#cuttlefish中allocator组成
libhidlbase.so #线程和IPC相关
android.hardware.graphics.allocator@4.0.so #BnHwAllocator实现
android.hardware.graphics.allocator@4.0-service.minigbm # main和CrosGralloc4Allocator实现
libminigbm_gralloc.so #cros_gralloc和virtgpu_virgl实现
libdrm.so #依赖

2.3 gralloc-minigbm框架

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#1. BnHwAllocator::onTransact binder接收消息，调用Gralloc4实现，另有Gralloc0实现
#2. CrosGralloc4Allocator框架，实现了init/initializeMetadata/allocate操作，通过cros_gralloc_driver实例调用其接口
#3. cros_gralloc_driver框架，实现了allocate/flush/lock等操作，直接调用drv框架
#4. Drv框架，实现了bo的一些操作，被cros_gralloc_driver和gbm调用，依赖于各厂商Gralloc后端实现，如drv_bo_create
#5. 各个厂商backend实现. 向drv框架注册驱动回调，如virtgpu_virgl 
const struct backend virtgpu_virgl = { .name = "virtgpu_virgl",
                       .init = virgl_init,
                       .close = virgl_close,
                       .bo_create = virgl_bo_create,
                       .bo_destroy = virgl_bo_destroy,
                       .bo_import = drv_prime_bo_import,
                       .bo_map = virgl_bo_map,
                       .bo_unmap = drv_bo_munmap,
                       .bo_invalidate = virgl_bo_invalidate,
                       .bo_flush = virgl_bo_flush,
                       .resolve_format_and_use_flags =
                       virgl_resolve_format_and_use_flags,
                       .resource_info = virgl_resource_info,
                       .get_max_texture_2d_size = virgl_get_max_texture_2d_size };

2.4 线程

allocator进程通常一个主线程，多个个binder线程，实际执行操作如bo create都在binder线程中进程

thread #1: name = 'allocator@4.0-s'
thread #2: name = 'HwBinder:412_1'
thread #3: name = 'HwBinder:412_2'
thread #4: name = 'HwBinder:412_3'

2.5 cuttlefish allocator

服务：android.hardware.graphics.allocator@4.0-service.minigbm
实现：/vendor/lib/libminigbm_gralloc.so 
源码：external/minigbm/
操作：需要图形界面有更新才有allocator内部操作

2.6 allocator跟踪

由于没有画面更新时allocator没有响应，在副屏启动web Activity看allocator都有哪些操作

am start -n com.android.webview/org.chromium.android_webview.devui.MainActivity --display 2

2.6.1 cuttlefish 2D模式

2D模式下，画面更新，基本是不断创建和销毁DUMB操作。内存操作最终依赖libdrm提供的接口

DRM_IOCTL_MODE_CREATE_DUMB -> drmPrimeHandleToFD -> DRM_IOCTL_MODE_DESTROY_DUMB ...

创建GraphicBuffer对象

IPCThreadState::getAndExecuteCommand
BnHwAllocator::onTransact #allocator@4.0.so
CrosGralloc4Allocator::allocate #allocator@4.0-service.minigbm
    cros_gralloc_driver::allocate  #libminigbm_gralloc.so
      drv_bo_create(width=777, height=471) 
        virgl_bo_create(width=400, height=600) 
          drv_dumb_bo_create_ex(..width=448, height=640) 
            #创建了一块内存放在了gem cma的对象里
            DRM_IOCTL_MODE_CREATE_DUMB
     drv_bo_get_plane_fd
       drmPrimeHandleToFD

销毁GraphicBuffer对象，与3D时接口不同

CrosGralloc4Allocator::allocate
  cros_gralloc_driver::release
    cros_gralloc_buffer::~cros_gralloc_buffer
      virgl_bo_destroy
        drv_dumb_bo_destroy
          DRM_IOCTL_MODE_DESTROY_DUMB

2.6.2 cuttlefish 3D模式

3D模式下，画面更新，基本是不断创建和销毁VIRTGPU_RESOURCE操作。内存操作最终依赖libdrm提供的接口

 DRM_IOCTL_VIRTGPU_RESOURCE_CREATE -> drmPrimeHandleToFD -> DRM_IOCTL_GEM_CLOSE ...

创建一个GraphicBuffer对象

BnHwAllocator::_hidl_allocate #allocator@4.0.so
  CrosGralloc4Allocator::allocate #allocator@4.0-service.minigbm
    cros_gralloc_driver::allocate #libminigbm_gralloc.so
      virgl_bo_create 
        virgl_3d_bo_create(bo=0xe8141090, width=400, height=600, format=875708993, use_flags=2597)
          DRM_IOCTL_VIRTGPU_RESOURCE_CREATE 
      drv_bo_get_plane_fd
        drmPrimeHandleToFD

销毁GraphicBuffer对象

CrosGralloc4Allocator::allocate
  cros_gralloc_driver::release
    cros_gralloc_buffer::~cros_gralloc_buffer
      virgl_bo_destroy
        drv_gem_bo_destroy
          DRM_IOCTL_GEM_CLOSE

2.7 其他实现

gralloc每个厂商实现不同，上文只分析了再Android模拟环境中minigbm实现，还有别的实现。

#ARM Mali GPU Gralloc
https://developer.arm.com/downloads/-/mali-drivers/android-gralloc-module
#源码目录driver\product\android\gralloc\src\4.x实现IAllocator 和 IMapper

#rk3588基于mali bifrost
https://github.com/rockchip-toybrick/rk_hardware_libgralloc_bifrost