#CPUArchitecture #ProgramCompilation #OperatingSystem #ComputerScience
Have you ever wondered why programs need to be compiled for a specific CPU architecture, even when they go through the operating system to interact with the system? π€ Let’s break it down for you in simple terms!
## Understanding the Basics
When you write a program in a language like Go, it needs to be translated into machine code that the CPU can understand. This process is known as compilation, where the source code is converted into a binary executable file. The resulting binary file is specific to the CPU architecture it was compiled for.
### Why Does it Matter?
Each CPU architecture has its own set of instructions and ways of processing data. When a program is compiled for a specific architecture, it is optimized to take advantage of the unique features and capabilities of that architecture. This optimization leads to better performance and efficiency when the program is executed on the CPU.
#### Example: Think of it like sending a message in a language that the receiver can understand. If the message is in a language the receiver doesn’t speak, they won’t be able to understand it, no matter how it’s delivered.
## Interaction with the Operating System
When a compiled program runs on the operating system, it still needs to communicate with the system to perform various tasks like file operations, network communication, and hardware interaction. The operating system acts as a mediator between the program and the hardware, providing an interface for the program to access system resources.
### The Role of CPU Architecture
Even though the program goes through the operating system to interact with the system, the instructions generated during compilation are specific to the CPU architecture. The operating system handles these instructions and translates them into commands that the CPU can execute efficiently.
#### Real-life Example: Imagine trying to drive a car using instructions written for a bicycle. The operating system acts as the driver, translating the instructions into actions that the car (CPU) can perform effectively.
## Practical Solutions
To ensure your programs are compiled correctly for the target CPU architecture, follow these practical tips:
1. Use the right compiler flags: Specify the target architecture when compiling your program to generate optimized machine code.
2. Test on different architectures: Validate your program on various CPU architectures to ensure compatibility and performance.
3. Stay updated: Keep up with the latest developments in CPU technology to leverage new features and enhancements.
In conclusion, compiling programs for a specific CPU architecture is essential for maximizing performance and efficiency, even when they interact with the system through the operating system. By understanding the role of CPU architecture in program compilation, you can optimize your code for better execution on different hardware platforms. Happy coding! π»π
Because compiled code such as c and c++ are converted to ASM code which is CPU Specicifc. Those parts that may call OS methods still need to know the specific CPU way of calling them.
The ASM code for ADD on an 86 architecture may be totally different on an ARM-based CPU. Also, memory addresses may be different for different architectures.
You’re correct that the OS is a middleman between programs and hardware.
The OS relies on the program code being specifically tailored to the CPU architecture for security and efficiency. This is because the OS uses machine code – the lowest level language a computer can understand directly.
Machine code is binary code specific to the processor architecture and it uniquely defines every instruction that the CPU can execute. Machine code is specific to the CPU (x86, ARM) because different CPUs are designed with different instruction sets – the operations that they can perform. This is why code compiled for one CPU architecture cannot run on a different CPU architecture.
Machine code specific to a particular CPU architecture also leverages the instruction set design to take advantage of its strengths and optimizations. This improves performance compared to interpreted languages such as Python that rely on the interpreter to translate code on the fly.
Different CPU architectures also have different kernel implementations such as kernel ring, protection ring or privilege levels. These are hardware-enforced privliege levels within the CPU architecture. It’s a layered design approach intended to prevent user-mode (un-privileged) programs from interfereing with the operating system core or other programs running at a higher privilege level.
Most programs do a lot more than just interacting with the OS. They do calculations, manipulate data, etc. all of that code wants to run as fast as possible, with the smallest memory footprint possible.
Compiling to native code is why, on average, a Go program will be faster than a Python program that does “the same thing”.
The premise is wrong, they don’t go through the OS for everything, the OS isn’t a language VM. They give instructions to the CPU directly.
If you look carefully they are not quite compiling to a cpu, but a combination of cpu + os
For
Example, for mac on apple silicon you compile for βdarwinβ
On βarm64β
Okay that out of the way, the operating systems apis and instructions are just different, they might have different names or different parameters depending on the amount of bits they need to work with. You write print() in a high level, but the underlying function can be 64__print() or 32__print() and those translate to different ways to the cpu, all OS and architecture dependant.
Each OS understands a different βexecutableβ format as well, which is, when you click/execute it, how does it know if itβs a program or a pdf? Portable executable
For windows, or ELF in linux.
Also, your compiled program doesnβt quite talk to the hardware directly, the operating systems manages how to talk to say the screen and the video card to print something. Back in the day, that was not necessarily the case, but that is about 40+ years now.
With all that information you can have a program running, and those are some reasons why they are specific
The program says to the OS, “Hey I have these instructions to run!”, the OS says “Those aren’t x86 instructions, they’re SPARC” (or whatever).
Even the Go print example, it doesn’t just tell the OS to print it out, it still does things for itself, i.e. a Go string isn’t the same as a “string” in whatever OS you use, it has to be converted first.
Programs interact with the OS, but programs still have to provide the correct information to the OS to work properly.
Different CPU:s (ie AARM, x86, MIPS,…) have different set of machine instructions that is used by the CPU to execute different low level tasks (ie increment a counter, perform an addition, move information between different memory locations).Β
A compiler is desigend to translate “human” code to a specific set of machine instructions that a specific CPU can execute (some compilers may be able to compile code to multiple sets of machine code, but only to one set of machine code at the time)
Programming languages may make use of predefined operations (ie the OS may expose operations that is used by the OS it self, the programming language/compiler may provide library functions for commonly used operations).
In the end, a CPU only executes low level machine code. Human readable code needs to be translated to machine code (statically by a compiler, on the fly by an interpreter or to an intermediate format that can be interpreted by a “virtual machine” to plattform specific machine code).
The OS isn’t a bytecode interpreter (usually, anyway). It is a set of APIs to control access to resources and external devices such that multiple programs can safely run concurrently.
Native code compiles to assembly. Assembly instructions vary between different CPU architectures. A lot of architectures don’t even have the same amount of instructions as other architectures.
A compiled program runs directly on the CPU, without OS. What it contains are instructions that are completely specific to the CPU, and that is why it cannot run somewhere else. There are mechanisms during the execution of a process (when doing system calls from the current running process or every certain time due to hardware support) that the os takes ownership again of the CPU to schedule another program, kill current process, etc and instantly gives the CPU back to the process. But the process itself, it runs directly on the CPU.
Programs don’t go through OS for everything. Simple things such as addition, assignment and goto execute directly on central precessor and therefore are processor specific.
even funnier is the case of IBM OS/360, eSeries and AS/400 stuff, the same programs run on very different hardware and OS versions
CPU architecture or , ISA (instruction set architecture), can be drastically different between different manufacturers.
If your ISA doesn’t support a specific instruction then your compiled binary will not run correctly.
Therefore you have to know all of the instructions of that CPU that you’re compiling the binary for.
Because you are not just telling the OS to print something out. When you are compiling a natively compiled programming language like C, Go or Rust you are generating raw machine instructions that run directly on the CPU. Yes, some of these instructions will involve telling the OS to print something or open a file or whatever, but the bulk of your compiled code is talking directly to the CPU.
Two things come to mind. Different CPU architectures have different instruction sets and memory models. So they are compiled into machine code differently based on the way their instruction sets laid out. And their memory models defines how memory is allocated, mapped, and targets the CPU. At the end of the days itβs all machine code but how that machine code gets compiled depends on the CPUs instruction set and memory model.