An executable binary file contains more than machine instructions

Why? Linux and Windows The executable of cannot be used universally ？

The main reasons are different formats and API Different , The former is more important .

An executable binary file contains more than machine instructions , It also includes various data 、 Program running resources , Machine instructions are only part of it .

One When an executable file is to be executed , The operating system needs to allocate resources , These resources include ： Memory space （ Physical and virtual ）, process 、 Thread resources and so on , The machine instructions of executable files are generally All in code snippets （ In assembly language, it is called text paragraph ）, Other resources may be put into data segments and other segments .

there “ paragraph ”（segment） It can be roughly understood as a memory range . Operating system system （Windows/Linux） You need to know how much memory this executable needs , How many segments , Which memory addresses are loaded respectively . The executable needs to tell the operating system , Be enforceable Line file prepares what things it can run .

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Executable before execution , The operating system needs some preparation , Because of the different operating systems , Preparation is different , So the format of executable file is not exactly the same .Windows Most of the executable files on are PE Format ,Linux Most executable files in are ELF Format . Different formats lead to different executable files that cannot be used directly across platforms . This is one of the reasons .

Yes, of course , I've seen great gods on the Internet solve some problems with different formats , But cross platform operation still needs to solve another obstacle , It's the operating system API Different . Most operations performed by an executable （ such as ： File operations 、 Input and output 、 Memory request release 、 Task scheduling and so on ） Need to interact with the operating system to complete , Different operating systems use these operations in completely different ways , So this obstacle is more difficult to overcome . This is the second reason .

Such as If we can solve the above two reasons , In theory, some executable files can span Windows and Linux stay x86 Running on the platform , because Intel and AMD Of CPU in , The main hard Piece instructions （ Machine instructions ） It's the same , in other words 0101 This binary number , It's the same . But if you switch to ARM platform , The bigger problem is that the hardware instructions are different , Then there is no way 了 .

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Is it possible to have executable files running across platforms , Theoretically, it exists , In the past, there were also some ways , But there are many restrictions , such as Windows too Go for support COM Format of the file , This file has no header , The size cannot exceed 64K, Only in one 16 In an environment （ Real or virtual ） function , Is a real bare binary . Linux In some BIN The file happens to be a raw binary （ There are some BIN No document ELF head , But not all BIN It's all like this ）.

After some configuration BIN Documents can also be found in Linux Running on . So some exquisitely designed COM/BIN Files can run across platforms under extremely restrictive circumstances , But maybe it can only be calculated , Unable to output , The size is only 64K Big , also If you want to do something a little more complicated , You need two sets of machine code to realize . in addition , unfortunately 64 In an environment COM Files are no longer supported .

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