我一直不清楚ABI是什么。别给我指维基百科上的文章。如果我能理解,我就不会在这里发这么长的帖子了。

这是我对不同界面的看法:

电视遥控器是用户和电视之间的接口。它是一个现有的实体,但本身无用(不提供任何功能)。遥控器上每个按钮的所有功能都在电视机中实现。

Interface: It is an "existing entity" layer between the functionality and consumer of that functionality. An interface by itself doesn't do anything. It just invokes the functionality lying behind. Now depending on who the user is there are different type of interfaces. Command Line Interface (CLI) commands are the existing entities, the consumer is the user and functionality lies behind. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: commands consumer: user Graphical User Interface(GUI) window, buttons, etc. are the existing entities, and again the consumer is the user and functionality lies behind. functionality: my software functionality which solves some problem to which we are describing this interface. existing entities: window, buttons etc.. consumer: user Application Programming Interface(API) functions (or to be more correct) interfaces (in interfaced based programming) are the existing entities, consumer here is another program not a user, and again functionality lies behind this layer. functionality: my software functionality which solves some problem to which we are describing this interface. existing entities: functions, Interfaces (array of functions). consumer: another program/application. Application Binary Interface (ABI) Here is where my problem starts. functionality: ??? existing entities: ??? consumer: ???

我用不同的语言编写过软件,并提供过不同类型的接口(CLI、GUI和API),但我不确定是否曾经提供过ABI。

维基百科说:

abi涵盖了诸如 数据类型、大小和对齐方式; 调用约定,它控制函数的实参 传递和返回检索到的值; 系统调用编号以及应用程序应该如何进行系统调用 到操作系统; 其他abi标准化细节,如 c++名字mangling, 异常传播,以及 调用约定的编译器之间在同一平台,但做 不需要跨平台兼容性。

谁需要这些细节?请不要说操作系统。我懂汇编编程。我知道如何链接和加载工作。我知道里面发生了什么。 为什么c++会出现名字混淆?我以为我们是在谈论二元的层面。为什么会出现语言?

无论如何,我已经下载了[PDF] System V应用程序二进制接口版4.1(1997-03-18)来看看它到底包含了什么。大部分都说不通啊。

Why does it contain two chapters (4th & 5th) to describe the ELF file format? In fact, these are the only two significant chapters of that specification. The rest of the chapters are "processor specific". Anyway, I though that it is a completely different topic. Please don't say that ELF file format specifications are the ABI. It doesn't qualify to be an interface according to the definition. I know, since we are talking at such a low level it must be very specific. But I'm not sure how is it "instruction set architecture (ISA)" specific? Where can I find Microsoft Windows' ABI?

这些是困扰我的主要问题。


当前回答

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。

其他回答

总结

对于定义ABI(应用程序二进制接口)的确切层有各种各样的解释和强烈的意见。

在我看来,ABI是对特定API的给定/平台的主观约定。ABI是对于特定API“不会改变”的约定的“剩余”部分,或者由运行时环境解决:执行器、工具、链接器、编译器、jvm和OS。

定义接口:ABI, API

如果你想使用像joda-time这样的库,你必须声明一个依赖joda-time-<major>.<minor>.<patch>.jar。标准库遵循最佳实践并使用语义版本控制。这在三个层次上定义了API的兼容性:

补丁——你根本不需要修改你的代码。这个库只是修复了一些错误。 次要-你不需要改变你的代码,因为添加的东西(开闭原则是尊重的) 重要—接口(API)已更改,您可能需要更改代码。

为了让你使用同一个库的一个新的主要版本,还有很多其他的约定需要遵守:

库使用的二进制语言(在Java情况下是定义Java字节码的JVM目标版本) 调用约定 JVM规范 链接约定 运行时约定 所有这些都是由我们使用的工具定义和管理的。

例子

Java案例研究

例如,Java标准化了所有这些约定,不是在一个工具中,而是在一个正式的JVM规范中。该规范允许其他供应商提供一组不同的工具来输出兼容的库。

Java为ABI提供了另外两个有趣的案例研究:Scala版本和Dalvik虚拟机。

Dalvik虚拟机破坏了ABI

The Dalvik VM needs a different type of bytecode than the Java bytecode. The Dalvik libraries are obtained by converting the Java bytecode (with same API) for Dalvik. In this way you can get two versions of the same API: defined by the original joda-time-1.7.2.jar. We could call it joda-time-1.7.2.jar and joda-time-1.7.2-dalvik.jar. They use a different ABI one is for the stack-oriented standard Java vms: Oracle's one, IBM's one, open Java or any other; and the second ABI is the one around Dalvik.

Scala后续版本不兼容

Scala在次要的Scala版本之间不具有二进制兼容性:2。X。由于这个原因,相同的API“io。reactivex" %% "rxscala" % "0.26.5"有三个版本(将来会有更多):针对Scala 2.10、2.11和2.12。改变了什么?我现在不知道,但是二进制文件是不兼容的。可能最新的版本增加了一些东西,使得库在旧的虚拟机上无法使用,可能是与链接/命名/参数约定有关的东西。

Java连续版本是不兼容的

Java在JVM的主要版本上也有问题:4,5,6,7,8,9。它们只提供向后兼容性。Jvm9知道如何运行针对所有其他版本的编译/目标代码(javac的-target选项),而JVM 4不知道如何运行针对JVM 5的代码。而你只有一个joda-library。由于有不同的解决方案,这种不兼容性变得显而易见:

语义版本控制:当库的目标是更高的JVM时,它们通常会改变主版本。 使用JVM 4作为ABI,您就安全了。 Java 9增加了一个关于如何在同一个库中包含特定目标JVM的字节码的规范。

为什么我要从API定义开始呢?

API and ABI are just conventions on how you define compatibility. The lower layers are generic in respect of a plethora of high level semantics. That's why it's easy to make some conventions. The first kind of conventions are about memory alignment, byte encoding, calling conventions, big and little endian encodings, etc. On top of them you get the executable conventions like others described, linking conventions, intermediate byte code like the one used by Java or LLVM IR used by GCC. Third you get conventions on how to find libraries, how to load them (see Java classloaders). As you go higher and higher in concepts you have new conventions that you consider as a given. That's why they didn't made it to the semantic versioning. They are implicit or collapsed in the major version. We could amend semantic versioning with <major>-<minor>-<patch>-<platform/ABI>. This is what is actually happening already: platform is already a rpm, dll, jar (JVM bytecode), war(jvm+web server), apk, 2.11 (specific Scala version) and so on. When you say APK you already talk about a specific ABI part of your API.

API可以移植到不同的ABI

抽象的顶层(针对最高API编写的源代码可以被重新编译/移植到任何其他较低层次的抽象。

假设我有一些rxscala的源代码。如果Scala工具改变了,我可以重新编译它们。如果JVM发生了变化,我就可以从旧机器自动转换到新机器,而不需要考虑高级概念。虽然移植可能很困难,但对任何其他客户端都有帮助。如果使用完全不同的汇编代码创建一个新的操作系统,则可以创建一个转换器。

跨语言移植的api

有些api可以移植到多种语言中,比如反应流。一般来说,它们定义到特定语言/平台的映射。我认为API是用人类语言甚至是特定的编程语言正式定义的主规范。在某种意义上,所有其他的“映射”都是ABI,比通常的ABI更多的API。REST接口也是如此。

实际上你根本不需要ABI如果

你的程序没有函数,而且—— 你的程序是一个单独运行的可执行文件(即一个嵌入式系统),它实际上是唯一在运行的东西,它不需要与其他任何东西对话。

过度简化的总结:

API:“这里是你可以调用的所有函数。” ABI:“这是调用函数的方法。”

ABI是编译器和链接器遵守的一组规则,以便编译您的程序,使其正常工作。ABIs涵盖多个主题:

Arguably the biggest and most important part of an ABI is the procedure call standard sometimes known as the "calling convention". Calling conventions standardize how "functions" are translated to assembly code. ABIs also dictate the how the names of exposed functions in libraries should be represented so that other code can call those libraries and know what arguments should be passed. This is called "name mangling". ABIs also dictate what type of data types can be used, how they must be aligned, and other low-level details.

更深入地了解调用约定,我认为它是ABI的核心:

机器本身没有“功能”的概念。当你用高级语言(如c)编写函数时,编译器会生成一行汇编代码,如_MyFunction1:。这是一个标签,它最终将被汇编程序解析为一个地址。这个标签标记了程序集代码中“函数”的“开始”。在高级代码中,当你“调用”这个函数时,你真正做的是导致CPU跳转到那个标签的地址并继续在那里执行。

在为跳转做准备时,编译器必须做一些重要的事情。调用约定就像一个清单,编译器遵循它来完成所有这些事情:

First, the compiler inserts a little bit of assembly code to save the current address, so that when your "function" is done, the CPU can jump back to the right place and continue executing. Next, the compiler generates assembly code to pass the arguments. Some calling conventions dictate that arguments should be put on the stack (in a particular order of course). Other conventions dictate that the arguments should be put in particular registers (depending on their data types of course). Still other conventions dictate that a specific combination of stack and registers should be used. Of course, if there was anything important in those registers before, those values are now overwritten and lost forever, so some calling conventions may dictate that the compiler should save some of those registers prior to putting the arguments in them. Now the compiler inserts a jump instruction telling the CPU to go to that label it made previously (_MyFunction1:). At this point, you can consider the CPU to be "in" your "function". At the end of the function, the compiler puts some assembly code that will make the CPU write the return value in the correct place. The calling convention will dictate whether the return value should be put into a particular register (depending on its type), or on the stack. Now it's time for clean-up. The calling convention will dictate where the compiler places the cleanup assembly code. Some conventions say that the caller must clean up the stack. This means that after the "function" is done and the CPU jumps back to where it was before, the very next code to be executed should be some very specific cleanup code. Other conventions say that the some particular parts of the cleanup code should be at the end of the "function" before the jump back.

有许多不同的abi /调用约定。主要有:

x86或x86-64 CPU(32位环境): CDECL STDCALL FASTCALL VECTORCALL THISCALL x86-64(64位环境): SYSTEMV MSNATIVE VECTORCALL ARM CPU(32位) AAPCS ARM处理器(64位) AAPCS64

这里有一个很棒的页面,它实际显示了为不同的abi编译时生成的程序集的差异。

另一件需要提及的事情是,ABI不仅仅与程序的可执行模块内部相关。链接器还使用它来确保程序正确调用库函数。您的计算机上运行着多个共享库,只要编译器知道它们各自使用的ABI,它就可以正确地从它们调用函数,而不会破坏堆栈。

编译器理解如何调用库函数是非常重要的。在一个托管平台上(也就是说,一个OS加载程序的平台),如果不调用内核,您的程序甚至不能闪烁。

为了调用共享库中的代码,或者在编译单元之间调用代码,object文件需要包含调用的标签。c++修改了方法标签的名称,以加强数据隐藏并允许重载方法。这就是为什么您不能混合来自不同c++编译器的文件,除非它们显式地支持相同的ABI。

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。

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!