我也试图理解ABI, JesperE的回答很有帮助。

从一个非常简单的角度来看，我们可以尝试通过考虑二进制兼容性来理解ABI。

KDE wiki将库定义为二进制兼容的，“如果动态链接到库的前版本的程序继续与库的新版本一起运行，而不需要重新编译”。有关动态链接的更多信息，请参阅静态链接与动态链接

现在，让我们试着看看一个库需要二进制兼容性的最基本方面(假设库没有源代码更改):

相同/向后兼容的指令集架构(处理器指令、寄存器文件结构、堆栈组织、内存访问类型，以及处理器可以直接访问的基本数据类型的大小、布局和对齐) 相同调用约定 同名混淆约定(如果Fortran程序需要调用一些c++库函数，这可能是需要的)。

当然，还有许多其他细节，但这主要是ABI所涵盖的内容。

更具体地回答你的问题，由以上，我们可以推断:

ABI功能:二进制兼容性 现有实体:现有程序/库/操作系统 消费者:库，操作系统

希望这能有所帮助!

应用程序二进制接口(ABI)类似于API，但是调用者不能在源代码级别上访问该函数。只有二进制表示是可访问的/可用的。

abi可以在处理器体系结构级别或操作系统级别定义。 abi是编译器的代码生成器阶段要遵循的标准。该标准由操作系统或处理器决定。

功能:定义机制/标准，使函数调用独立于实现语言或特定的编译器/链接器/工具链。提供允许JNI或Python-C接口等的机制。

现有实体:机器代码形式的函数。

消费者:另一个函数(包括用另一种语言编写的、由另一种编译器编译或由另一种链接器链接的函数)。

让我至少回答你问题的一部分。通过一个例子说明Linux ABI如何影响系统调用，以及它为什么有用。

A systemcall is a way for a userspace program to ask the kernelspace for something. It works by putting the numeric code for the call and the argument in a certain register and triggering an interrupt. Than a switch occurs to kernelspace and the kernel looks up the numeric code and the argument, handles the request, puts the result back into a register and triggers a switch back to userspace. This is needed for example when the application wants to allocate memory or open a file (syscalls "brk" and "open").

现在系统调用有简短的名称“brk”等和相应的操作码，这些在系统特定的头文件中定义。只要这些操作码保持不变，您就可以使用不同更新的内核运行相同的已编译用户域程序，而无需重新编译。这样就有了预编译二进制文件使用的接口，因此就有了ABI。

答:简单地说，ABI与API的一个共同之处是它是一个接口。可重用程序公开了一个稳定的接口(API)，可用于在另一个程序中重用该程序。

B. However, an ABI is an interface issued for some specific processor-platform for some specific language. All compiler-vendors desiring to target that platform for that same language will have to ensure that not only compiled code in form of relocatable object codes comply with the interface to be able to link and cross-link with each other but also executables comply with it to be able to run on the platform at all. So, ABI is much broader set of specifications/standard than a typical function API. It may include some API objects to be enforced upon the language-users by the compiler. The compiler-vendor will have to include support for the same in their distributions. Needless to say, the platform vendor is the rightful authority to issue ABIs for its platform. Both compiler vendors and ABIs need to comply with the corresponding language-standard (e.g. ISO standard for C++).

C.平台供应商对ABI的定义是:

“1。可执行文件为了在特定的执行环境中执行而必须遵守的规范。例如，Arm架构的Linux ABI。

独立生成的可重定位文件必须遵守的规范的一个特定方面，以便静态可链接和可执行。例如，Arm架构的c++ ABI, Arm架构的运行时ABI, Arm架构的C库ABI。”

D.举例;基于Itanium架构的c++通用ABI也由一个联盟发布。平台供应商自己的c++的abi在多大程度上符合它完全取决于平台供应商。

E.作为另一个例子。Arm架构的c++ ABI在这里。

F.前面已经说过，处理器体系结构的ABI将确保一个可重用程序和另一个重用它的程序之间的API适用于该处理器体系结构。

G. That brings us to service-oriented components (e.g. SOAP-based web services). They too require an API to exist between a SOAP-based web service and client program (could be an app, front-end or another web service) for the client program to reuse the web service.The API is described in terms of standardized protocols like WSDL (interface description) and SOAP(message format) and is language-neutral and platform-neutral. It is not targeted to any specific processor-platform and thus it is not "binary" like ABI. A client-program on any one platform type and written in any language can remotely reuse a web service written in any other language and hosted on an entirely different processor-platform. This is made possible by the fact that both WSDL and SOAP are text-based (XML) protocols. In case of RESTful web services, the transport protocol http--also a text-based protocol-- itself acts as the API (CRUD methods).

简而言之，从哲学上讲，只有某种类型的东西才能相处得很好，而ABI可以被看作是一种软件东西一起工作的东西。

应用二进制接口(ABI)

ABI -应用二进制接口是关于运行时两个二进制部分之间的机器码通信，如应用程序，库，操作系统…ABI描述了如何将对象保存在内存中，如何调用函数(调用约定)，如何修改…

API和ABI的一个很好的例子是iOS生态系统从v5开始使用Swift语言。

Application layer - When you create an application using different languages. For example you can create application using Swift and Objective-C[Mixing Swift and Objective-C] Application - OS layer - runtime - Swift Standard Library and Swift Run Time Library[About] are parts of OS and they should not be included into each bundle(e.g. app, framework). It is the same as like Objective-C uses. Available from iOS v12.2 Library layer - Module Stability case - compile time - you will be able to import a framework which was built with another version of Swift's compiler. It means that it is safety to create a closed-source(pre-build) binary which will be consumed by a different version of compiler( .swiftinterface is used with .swiftmodule[About]) and you will not get Module compiled with _ cannot be imported by the _ compiler //or Compiled module was created by a newer version of the compiler Library layer - Library Evolution case Compile time - if a dependency was changed, a client has not to be recompiled. Runtime - a system library or a dynamic framework can be hot-swapped by a new one.

[API vs ABI] [Swift模块稳定性和库稳定性]