I'm seeing a lot of conflict information and would like some clarification.
build, host and target
There are three system names that the build knows about: the machine you are building on (build), the machine that you are building for (host), and the machine that GCC will produce code for (target). When you configure GCC, you specify these with --build=, --host=, and --target=.
Actually, I don't understand what the difference between host and target in the above definition.
Some other page says
‘host’ is the machine (or architecture, or platform) that you are using to compile the code;
‘target’ is the machine (or architecture, or platform) that is intended to run the code.
This makes sense to me, but in this explanation, is the host always the same as the build ?? I'm pretty confused.
In my case, I am configuring such that
the compiler (GCC) runs on x86_64 machine and the binary executable runs on ARM. The program is written in C, so the compiler is GCC.
./configure --build=x86_64 --host=x86_64 --target=arm-linux-gnueabihf
make
make install
It sounds like
build, host are both x86_64 and target is arm. Is that correct?
I am compiling my own embedded program that runs on Jenkins machine (x86_64). And the embedded program runs on ARM based machine.
Lets say I have a PowerPC machine making a compiler that you will use (run) on an x86 machine that will make binaries that run on an ARM.
That makes the PPC the build, the x86 the host, and the target is the ARM. As Basile commented, this is a Canadian-cross.
It's less common to have a build and host that are different, but it certainly does happen. Sometimes the build and host are even the same architecture, but there's something different about the environments that cause this. Making a custom toolchain on my x86 will mean that build and host are x86, but the host may have different libraries, or versions of dependencies, than the build. This is the case when building sand-boxed toolchains for embedded development that run on a build server, for example.
"There are three system names that the build knows about: the machine you are building on (build), the machine that you are building for (host), and the machine that GCC will produce code for (target). When you configure GCC, you specify these with --build=, --host=, and --target="
...
If build, host, and target are all the same, this is called a native.
If build and host are the same but target is different, this is called a cross.
If build, host, and target are all different this is called a canadian (for obscure reasons dealing with Canada’s political party and the background of the person working on the build at that time).
If host and target are the same, but build is different, you are using a cross-compiler to build a native for a different system.
Some people call this a host-x-host, crossed native, or cross-built native.
If build and target are the same, but host is different, you are using a cross compiler to build a cross compiler that produces code for the machine you’re building on.
This is rare, so there is no common way of describing it. There is a proposal to call this a crossback.
Source: https://gcc.gnu.org/onlinedocs/gccint/Configure-Terms.html
Someone already gave an example of the 'Canadian'.
An example of a cross-compilation is that when building sox from source (the Linux sound library) you need to provide 32-bit binaries for the codecs etc. I just came across this situation on a 64-bit machine, and I want to build it for my own use, which means in this case:
The build is the host (my machine)
The target is a 32-bit system
This is my understanding anyway, I agree this can be a bit confusingly explained, hope this helps :-)
Related
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.
I have an embedded system on a portable ARM device, and it runs a customized Linux. How can I build a native compiler for that Linux distro?
For example, I am now using machine A, and on A, I have both native compiler, and a cross-compiler for machine B. How can I build a compiler that can run directly on B?
I searched a bit, but only to find some tutorials of how to build cross compiler for B, but did not find how to build a native compiler through a cross compiler.
I'm not sure the marked answer is correct. I'm working on a project that mirrors the one in the original question and according to the link that n.m. posted, the original asker is attempting is called one of three things: a host-x-host, crossed native, or cross-built native...NOT a Canadian-Cross.
Unfortunately there does not seem to be any tutorials on this subject...at least none that I could find.
As I understand your question, you have fast non-ARM host and slow ARM. You want to build a compiler on your fast host; and compiler will be used on ARM system to compile code to ARM machine.
This setup is almost classic Canadian Cross:
Given three machines A, B, and C, one uses machine A (e.g. running Windows XP on an IA-32 processor) to build a cross compiler that runs on machine B (e.g. running Mac OS X on an x86-64 processor) to create executables for machine C (e.g. running Android on an ARM processor).
You have B=C and can use Canadian Cross build systems.
Unfortunately, this type of cross compilers are the hardest one. There are some manual to build such Cross: http://airs.com/ian/configure/configure_6.html ... or try to google "canadian cross gcc".
There are also some scripts to build embedded systems based on Linux. Will try to search some and add them here:
http://crosstool-ng.org/ (toolchain building with some canadian support)
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.