IODeviceMemory声明在哪个KPI库中? | IODeviceMemory声明在哪个KPI库中

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问题描述

Google没有洞察力.我无法通过搜索找出答案在内核源代码中.

Google yields no insight. I wasn't able to figure it out by searchingaround in the kernel source.

我正在使用开源IOProxyVideoFamily来实现虚拟帧缓冲区.

I'm using the open source IOProxyVideoFamily to implement a virtual framebuffer.

我刚刚用OSDynamicCast替换了对IODeviceMemory的C样式强制转换，因为我怀疑演员会失败.如果是这样，我会知道如何解决它.

I just replaced a C-style cast to IODeviceMemory with OSDynamicCast,because I suspect that cast will fail. If so I will know how to fixit.

但是我找不到包含它的KPI库. IODeviceMemory具有从10.0开始就在操作系统中使用，并且对于PCI卡驱动程序是必需的.

But I can't find the KPI library that contains it. IODeviceMemory hasbeen in the OS since 10.0, and is required for PCI card drivers.

$ kextlibs -undef-symbols /System/Library/Extensions/IOProxyFramebuffer.kext/

For all architectures:
   com.apple.iokit.IOGraphicsFamily = 2.4.1
   com.apple.kpi.iokit = 15.6
   com.apple.kpi.libkern = 15.6
   com.doequalsglory.driver.IOProxyVideoCard = 1.0d1

For x86_64:
   1 symbol not found in any library kext:
   ZN14IODeviceMemory9metaClassE

IODeviceMemory是IOMemoryDescriptor的子类.这是宣言包括OSDeclareDefaultStructors.

IODeviceMemory is a subclass of IOMemoryDescriptor. It's declarationincludes OSDeclareDefaultStructors.

(当视频卡满足对IOProxyVideoCard的依赖性驱动程序已安装.)

(The dependence on IOProxyVideoCard is satisfied when the video carddriver is installed.)

推荐答案

IODeviceMemory是一个奇怪的IOMemoryDescriptor子类，因为它不覆盖任何虚函数并且不添加任何字段.因此，实际上，它只是IOMemoryDescriptor的一些静态帮助器函数.如果查看这些帮助程序功能的源代码，则会发现没有一个实际上创建了IODeviceMemory 的实例-而是调用了IOSubMemoryDescriptor::withSubRange()(显然会创建一个IOSubMemoryDescriptor对象)和IOMemoryDescriptor::withAddressRange()(我相信后者会创建一个IOGeneralMemoryDescriptor).

IODeviceMemory is a weird IOMemoryDescriptor subclass in that it doesn't override any virtual functions and doesn't add any fields. So it's really just a few static helper functions for IOMemoryDescriptor. If you look at the source code for those helper functions, you'll find that none of them actually create an instance of IODeviceMemory - instead they call down to IOSubMemoryDescriptor::withSubRange() (which obviously creates an IOSubMemoryDescriptor object) and IOMemoryDescriptor::withAddressRange() (I believe this latter one creates an IOGeneralMemoryDescriptor).

所以您的动态强制转换无论如何都不起作用，IODeviceMemory并不真正存在-通常没有实例.我怀疑这就是为什么自动生成的OSMetaClass东西没有通过KPI导出的原因.

So your dynamic cast wouldn't work anyway, IODeviceMemory doesn't really exist - there are normally no instances of it around. I suspect this is why the auto-generated OSMetaClass stuff for it isn't exported via a KPI.

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