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。
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).
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!
区分ABI和API的最好方法是了解它的用途和原因:
对于x86-64,通常有一个ABI(对于x86 32位,有另一组ABI):
http://www.x86-64.org/documentation/abi.pdf
https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/LowLevelABI/140-x86-64_Function_Calling_Conventions/x86_64.html
http://people.freebsd.org/~obrien/amd64-elf-abi.pdf
Linux + FreeBSD + MacOSX紧随其后,略有变化。Windows x64有自己的ABI:
http://eli.thegreenplace.net/2011/09/06/stack-frame-layout-on-x86-64/
Knowing the ABI and assuming other compiler follows it as well, then the binaries theoretically know how to call each other (libraries API in particular) and pass parameters over the stack or by registers etc. Or what registers will be changed upon calling the functions etc. Essentially these knowledge will help software to integrate with one another. Knowing the order of the registers / stack layout I can easily piece together different software written in assemblies together without much problem.
但是API是不同的:
它是一个定义了参数的高级函数名,这样如果不同的软件使用这些API构建,就可以相互调用。但是必须遵守SAME ABI的附加要求。
例如,Windows曾经是POSIX API兼容的:
https://en.wikipedia.org/wiki/Windows_Services_for_UNIX
https://en.wikipedia.org/wiki/POSIX
Linux也是POSIX兼容的。但是二进制文件不能被移动并立即运行。但是因为它们在POSIX兼容的API中使用了相同的NAMES,所以您可以在C语言中使用相同的软件,在不同的操作系统中重新编译它,并立即让它运行起来。
API是为了简化软件集成-预编译阶段。所以在编译之后,如果ABI不同的话,软件看起来会完全不同。
ABI的目的是在二进制/汇编级别定义软件的精确集成。
如果您了解汇编以及操作系统级别的工作方式,那么您就符合特定的ABI。ABI控制参数的传递方式、返回值放置的位置等。对于许多平台来说,只有一种ABI可供选择,在这些情况下,ABI只是“事情如何工作”。
然而,ABI也控制着c++中类/对象的布局。如果您希望能够跨模块边界传递对象引用,或者如果您希望混合使用不同编译器编译的代码,这是必要的。
此外,如果您有一个可以执行32位二进制文件的64位操作系统,那么32位和64位代码将有不同的abi。
通常,链接到相同可执行文件中的任何代码都必须符合相同的ABI。如果希望在使用不同abi的代码之间进行通信,则必须使用某种形式的RPC或序列化协议。
我认为你过于努力地将不同类型的界面挤进一个固定的特征集。例如,一个界面不一定要分成消费者和生产者。接口只是两个实体交互的约定。
abi可以(部分地)与isa无关。有些方面(如调用约定)依赖于ISA,而其他方面(如c++类布局)则不依赖于ISA。
定义良好的ABI对于编写编译器的人来说非常重要。如果没有定义良好的ABI,就不可能生成可互操作的代码。
编辑:需要澄清的一些注释:
ABI中的“二进制”并不排除字符串或文本的使用。如果您想要链接一个导出c++类的DLL,则必须对其中的方法和类型签名进行编码。这就是c++名称破坏的用武之地。
您从未提供ABI的原因是绝大多数程序员都不会这样做。ABI是由设计平台(即操作系统)的人提供的,很少有程序员有特权设计一个广泛使用的ABI。