Is it possible for gcc, installed on fedora 16, to cross compile for a different CPU, say SPARC?
I have build a certain understanding, need some expert to correct me if I am wrong. Different operating systems differ by the system calls they use to access the kernel or entirely by the kernel they use. IS THIS CORRECT? different kernels understands different systems calls for accessing underlying hardware. binaries or executables or programs are nothing but a bunch of system calls only. therefore every OS has its own executable. an executable meant to run to on windows wound not run on linux. by cross compiling the source code of any windown's executable we can generate executable for other OSs. word PLATFORM means operating system. POSIX are certain design standards for UNIX-like OSs.
we usually cross compile for different OSs. BUT can we cross compile for different hardware too? for example, in case of a microcontroller which does not have an OS?
No. You can't use native machine (x86) gcc for compiling program files for a different architecture. For that you require a cross-compiler-gcc that is specific to that processor architecture.
Your understanding about system calls for OS is correct. Each OS has its own set of system call which is been used by library. These libraries at the end will be translated into machine language for the processor.
Each Processor Architecture has its own set of instruction know as Instruction Set Architecture(ISA). So when a program written in high-level-language (like C) is compiled, it should be converted into machine language from its ISA. This job is done by the compiler(gcc). A compiler will be specific to only one processor architecture. For example gcc is for x86 processor. So if you want a compiler for different processor in you x86 machine you should go for a cross-compiler of that processor.
You would have to build such a version. That's part of the process of porting gcc to a new platform. You build a version that cross-compiles, then you cross-compile that version, then you test that version on the new platform, debug, rinse, and repeat.
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I try to understand this whole "compiling" topic in a way more detailed than all those "what is a compiler (doing)?" articles out there.
One big question to me is processor- and os-platform dependency when compiling directly to machine code (e.g. C). I try to formulate concrete questions that needs to be resolved in order to get my picture clearer:
I compile my C code via gcc on a Linux distribution... :
Can I run the resulting executable on any other Linux Distribution?
Is that executable bound the processor platform compiled on? Do I need to search for another e.g. power-pc gcc when I am running a x86 distro?
Can I somehow execute this on windows? I know executables differs but the binary code is the same, isn't it?
So in the end my questions aims on: Is compiling about targeting a specifiy OS paltform, processor platform or both?
Thanks!
Compiling targets both, OS, and Architecture.
The OS needs to be targeted because:
The format of what is an "executable" file is different among operating systems.
Programs call the operating system even for common tasks like writing to the console, reading from a file, or terminating cleanly (standards like POSIX mitigate OS dependencies by defining a common layer between the program and the OS).
The CPU architecture must be targeted because the CPU instructions are different, even among different generations of the "same architecture".
Can I run the resulting executable on any other Linux Distribution?
In general, Yes, but on specific cases it may depend on the type of program (f.i. GUI) and the services assumed available on the OS.
Is that executable bound the the processor platform compiled on? Do I need to search for another e.g. power-pc gcc when I am running a x86 distro?
I don't understand what you mean by "search", but, Yes, you can cross-compile from, say, x86 targeting PPC.
Can I somehow execute this on Windows? I know executables differ but the binary code is the same, isn't it?
These days Windows has Ubuntu integration, and that allows for some kind of exceptions, but the general answer is No, because of the above.
I am very new to linux and GCC. The price of raspberry pi lured me in. I am interested in using GCC to cross compile some C Code to target some embedded hardware, specifically a Cortex-M3 micro. I eventually want to have a full suite of compiler/programmer/debugger, but for now I'm starting with compiler.
So I did a quick non-cross compile test on the RP3, and all was well. Now I am researching how to cross compile and target my uc. The gcc documentation online seems to indicate that I can use the plain vanilla gcc, and just specify some command line options to perform cross compilation: https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html
But searching around, I find a lot of people mentioning building a gcc cross compiler. What does this mean?
Does gcc have options to double as a cross compiler? If so, why would one desire "building" a cross compiler?
A cross-compiler is one that is created on machine type A (combination of hardware and o/s) and either runs on a different machine type B or runs on type A but produces software to be run on a different machine type B.
Thus, if you have a Linux machine using an x86_64 CPU and running on some version of Linux, but you compile GCC so that it will run on an IBM PowerPC platform running some version of AIX, you would be creating a cross-compiler.
Another variant might be having a compiler on Linux using an x86_64 CPU that runs on the Linux machine but produces code for an embedded hardware chip. You'd then benefit from the CPU power of the Linux machine while deploying to a much smaller, less powerful system that maybe has no o/s of its own, or only a minimal o/s.
Since I have started to learn Golang since yesterday :) I have a question about the compiled file.
Let's assume that I compile my project. It generates an .exec file in /bin folder.
Now my question is Since the file has been compiled on Mac with Intel based CPU, should it be compiled on other OS and other CPU architectures such as AMD, ARM, etc. if I want to publish it to public?
I guess this should not be problem if I'm using GO lang for my backend since I run it on a server. However, what happens if I publish my .exec file, let's say on AWS, with lots of instances that they are automatically increases/decreases based on load? Does it problem?
Edit:
This is nice solution for those how are looking Go cross compiling tool https://github.com/mitchellh/gox
The answer to the first question is yes. The current implementations of Go produce a native binary, so you will probably need a different one for Linux x86 (32-bit), Linux x64 (64-bit), and Linux ARM. You will probably need a different one for Mac OS X also. You should be able to run the 32-bit executable on a 64-bit system as long as any libraries you depend on are available in 32-bit form on that system, so you might be able to skip making a 64-bit executable.
In the future, there may be other implementations of Go that compile for a virtual machine (such as JVM or .NET), in which case you wouldn't need to compile multiple versions for different architectures. Your question is more about existing Go implementations than the language itself.
I don't know anything about AWS, but I suggest you ask that as a separate question.
what is cross compilation?
Cross-compilation is the act of compiling code for one computer system (often known as the target) on a different system, called the host.
It's a very useful technique, for instance when the target system is too small to host the compiler and all relevant files.
Common examples include many embedded systems, but also typical game consoles.
A cross-compiler is compiles the source code from one architecture to another architecture.
For example: hello.c
gcc hello.c (gcc is a compiler for x86 architecture.)
arm-cortexa8-linux-gnueabihf-gcc hello.c
(arm-....-gcc is a compiler for the arm architecture.) This you are compiling on the host pc for a target board (e.g rpi, beaglebone, wega board). In this example arm-cortexa8-linux-gnueabihf-gcc is called the 'cross compiler'.
This process is called cross compilation.
see the link for more info cross compilation
To "cross compile" is to compile source on say a Linux box with intent on running it on a MAC or Windows box. This is usually done using a cross compilation plugin, which are readily available from various web servers across the net. If one is to install a cross compilation plugin onto their Linux box that is designed to compile for Windows boxes. Then they may compile for either a Linux/*NIX box as well as have the option to compile and link a Windows-ready executable. This is extremely convenient for a freelance programmer whom has access to no more than a single Linux/Windows/MAC box. Note that various cross compilation plugins will allow for multitudes of applications, some of which you may or may not perceive as useful, thus a thorough perusal of the plugin's README file.
Did you have a particular project in mind that you would like to apply the method of cross compilation to?
In a strict sense, it is the compilation of code on one host that is intended to run on another.
Most commonly it is used with reference to compilation for architectures that are not binary-compatible with the host -- for instance, building RISC binaries on a CISC CPU platform, or 64-bit binaries on a 32-bit system. Or, for example, building firmware intended to run on embedded devices (perhaps using the ARM CPU architecture) on Intel PC-based OSs.
A Cross Compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running.
For e.g. a compiler that runs on a Windows 7 PC but generates code that runs on Android smartphone is a cross compiler.
A cross compiler is necessary to compile for multiple platforms from one machine.
A platform could be infeasible for a compiler to run on, such as for the microcontroller of an embedded system because those systems contain no operating system.
In paravirtualization one machine runs many operating systems, and a cross compiler could generate an executable for each of them from one main source.
I wish to build a compiler (GCC port) for Linux, so that the built GCC runs on Windows and creates executables for an embedded platform.
Is the above possible?
Yes, it is possible.
It also utterly painful to try to do this yourself -- it is OK on Linux, mostly, but very tricky on Windows. My suggestion is to see if some ready-built compiler from a place like DENX.de, CodeSourcery, or the manufacturer of your embedded platform is available.
I have become a huge fan of the CodeSourcery compilers for platforms like MIPS and Power Architecture. They tend to come with variants for big- and little-endian, various Libc flavors, and to have both bare-metal and linux-target versions available. See their pages about their Lite edition
Building your own cross-compiler and toolset is a right pain.
If your target is running Linux, I suggest doing your cross-work on a Linux box as well, saving you plenty of pain. I use VmWare for that express purpose. You cannot expect to build a Linux for a target on Windows, for example.
In embedded systems compilers are referred based on processor architecture and not on OS. What you probably want is to build a "cross compiler" for a processor other than the one running in your Windows machine. This is of course possible. See for example the WinAVR and WinARM projects. These are compilers for AVR and ARM processor architectures, based on GCC and running in Windows machines. Another example is yagarto. These aren't just a compiler, but a full tool chain that will allow you to built Linux executables (for ARM processors), if the requires libraries are available.
Because GCC relies on POSIX functionality that is not available in Windows natively, you need a Linux-like environment for Windows (such as Cygwin or MinGW).
http://cegcc.sourceforge.net
If you are satisfied to running it on Windows then at www.gnupit.org you can donwload ready GCC cross toolchain for free. There are many target platforms.
You have to build GCC on Windows using MinGW or Cygwin for your target platform (e.g. ARM little endian).