I have an embedded project for ARM platform, specifically aarch64.
Up until now I was using Make. I recently set up CMake with no particular issues.
I moved to CMake because I was under the impression it was a more modern build tool that would have allowed a smarter configuration.
For example, I can compile my project using different toolchains (aarch64-elf-gcc-linaro, aarch64-linux-gnu-gcc,...) and I would like CMake to try if any of those are installed on the system and use whichever is found first by default.
Is this possible (or meant to)? I'd expect it to be an easy feat for the tool, but after searching for a while I can't seem to find the right track.
Yes, you can make your CMake project to search for available tool-chains installed in your OS, choose one and compile your project. I also write a CMake program for ARM embedded project, because now it is universal transferable between different OS system Windows and Unix. On Linux there is ARM ToolChain installed and on Windows there is Keil-MDK. If you have different tool-chains to choose between, you can write CMake script which will find paths with command like find_path() and then call correct "toolchianxx.cmake" script with right compiler flags for chosen compiler.
In your particular problem just use find_path commands and use hits to find installed compilers in "pre-set" known paths.
I am working on a project on linux and I dont understand
what really is cmake?
I have clion IDE do I explicitly need to learn about cmake?
Does Clion have cmake internally?
I am working on object detection with open detection.
CMake is sort of a wrapper around older, more complex, and often more powerful make systems. Make systems are a big topic, but in short, it is their job to notice files and do something about it (compile, link, deploy, etc)
CLion is a full GUI IDE which in turn uses CMake to do its dirty work of tracking files and what to do about them. Its primary purpose is to wrap up your compilation (via cmake) as well as give you text editors suited to the task at hand. Importantly, it also is a GUI front end for your debugging needs.
Is it possible generate build systems on one platform for another using cmake? For example, and the case I'm most interested in, is it possible to generate a set of Visual Studio solution files, or mingw32-make Makefiles, or nmake files, for a project from Linux?
The intention is to make something analogous to what the make dist target produces in automake. However, I don't need it to do as much as make dist does, i.e. I just want to generate the solution files as though I'd run cmake in Windows.
Users can then build the package using the created build system on their own machines.
If it is possible, how do I do it? Cmake doesn’t report the Windows based generators as being available on Linux.
After further research I believe the answer to my question is no. The reason is that the makefiles and solution files etc. produced by cmake depend on cmake itself, the path to which is hard-coded into the files.
One solution for windows might be to bundle the cmake executable with your files and replace the definition of CMAKE_COMMAND (for instance) added to makefiles with the path to your bundled version of cmake somehow. This is just a suggestion though, I haven't tried or even researched it much. If you do, please post the process as a comment or answer here.
I'm currently investigating cmake to allow automatic building on the Win32 platform. For all runtimes and libraries I'd like to build, Visual Studio (2008/2010) projects do allready exist.
I've come across cmake, but I'm unsure if I really need it. As the documentation says, cmake generates VS projects and they then can be built e.g. using MSBuild.
As the projects itself allready do exist (and build nicely via the IDE or MSBuild on the cmd line), what do I need and use cmake for? Just for directory/project folder traversal? Build failure reporting?
Regards,
Paul
Well, strictly speaking you do not need it. However, it does give you a few advantages:
The idiomatic way to use CMake, forces you to use out-of-source builds. Arguable, but I am personally convinced that these keep you source-repository very clean.
You can support multiple visual studio versions (with the out-of-source builds). Perhaps it will be a little easier to port your project to other compilers (from MinGW -> Linux GCC).
With the find_package and config.cmake files, and a large number of available findXXX modules, CMake makes it a lot easier to "import" third-party libraries into your build-chain.
You don't need it. Cmake is only useful if you are trying to keep the same source code able to build in multiple platforms and compilers. If you are simply building using the microsoft stack you have no need of it.
I have been looking for pros & cons of Autotools and CMake. But I would like to know opinions from people having used one (or both) of these tools for projects.
I used Autotools very basically a year ago and I know that one of the good points is that it relies on shell scripting, thus it does not need to be installed to be run and uses portable shell scripting. But it looks like it is too unix oriented, and it would not be possible to run the configure file on Windows.
I have now to choose a build system tool for an open source project that will have to be compiled for at least Linux & Windows. It is written in C++, and uses a Qt GUI front-end, the rest of it is "generic".
Thanks for you help.
Updated 16th of January 2019: Refined advice as tools evolve.
I have used autotools before for a considerable amount of time.
Currently I make intensive use of meson and cmake only when I need it.
Some personal advice:
for big teams, stick to CMake if you want to make use of the generators for XCode. If you do not need it, I would use Meson directly. Meson, as of version 0.49, also supports finding CMake configuration files (though I did not test yet how well this works). Also, Visual Studio seems to be sufficiently well-supported at this point in time, though, again, I did not try myself. The advantage of CMake is that it has Visual Studio integration.
Drop autotools. Meson covers well everything already. Their cross-compilation model is amazingly understandable. In CMake, last time I checked, everything was quite more difficult.
I have also tried scons, waf, and tup.
The most full-featured, cross-platform system, is CMake, but the DSL from meson will be easier to use for people used to python and others. Meson is starting to support VS also (a VS2015 generator) and some projects already have experimental support for it, for example gstreamer. Gstreamer is compiled in windows as well with meson. Right now there is VS2015 generator and VS2017 but I did not try myself the generators lately. As of meson 0.37.1 needed some work, but they are improving them and current version is already 0.40.
Meson
Pros:
The DSL does not get in the way at all. In fact, it is very nice and familiar, based in python.
Well-thought cross compilation support.
The objects are all strongly typed: you cannot make string substitution mistakes easily, since objects are entities such as 'depencency', 'include directory', etc.
It is very obviuos how to add a module for one of your tools.
Cross-compilation seems more straightforward to use.
Really well-thought. The designer and main writer of Meson knows what
he talks about very well when designing a build system.
Very, very fast, especially in incremental builds.
The documentation is 10 times better that what you can find in cmake. Go visit http://mesonbuild.com and you will find tutorial, howtos and a good reference. It is not perfect but it is really discoverable.
Cons:
Not as mature as CMake, though, I consider it already fully usable for C++.
Not so many modules available, though, gnome, qt and the common ones are already there.
Project generators: seems VS generator is not working that well as of now. CMake project generators are far more mature.
Has a python3 + ninja dependency.
Cmake
Pros:
Generates projects for many different IDEs. This is a very nice feature for teams.
Plays well with windows tools, unlike autotools.
Mature, almost de-facto standard.
Microsoft is working on CMake integration for Visual Studio.
Cons:
It does not follow any well known standard or guidelines.
No uninstall target.
The DSL is weird, when you start to do comparisons and such, and the strings vs list thing or escape chars, you will make many mistakes, I am pretty sure.
Cross compilation sucks.
Autotools
Pros:
Most powerful system for cross-compilation, IMHO.
The generated scripts don't need anything else than make, a shell and, if you need it to build, a compiler.
The command-line is really nice and consistent.
A standard in unix world, lots of docs.
Really powerful command-line: changing directories of installation, uninstall,
renaming binaries...
If you target unix, packaging sources with this tool is really convenient.
Cons:
It won't play well with microsoft tools. A real showstopper.
The learning curve is... well... But actually I can say that CMake was not that easy either.
The use of recursive make is pervasive in legacy projects. Automake supports non-recursive builds, but it's not a very widely used approach.
About the learning curve, there are two very good sources to learn from:
The website here
The book here
The first source will get you up and running faster. The book is a more in-depth discussion.
From Scons, waf and tup, Scons and tup are more like make. Waf is more like CMake and the autotools. I tried waf instead of cmake at first. I think it is overengineered in the sense that it has a full OOP API. The scripts didn't look short at all and it was really confusing for me the working directory stuff and related things. At the end, I found that autotools and CMake are a better choice. My favourite from these 3 build systems is tup.
Tup
Pros
Really correct.
Insanely fast. You should try it to believe it.
The scripting language relies on a very easy idea that can be understood in 10 minutes.
Cons
It does not have a full-featured config framework.
I couldn't find the way to make targets such as doc, since
they generate files I don't know of and they must be listed in the output before being generated, or at least, that's my conclusion for now. This was a really annoying limitation, if it is, since I am not sure.
All in all, the only things I am considering right now for new projects is are Cmake and Meson. When I have a chance I will try tup also, but it lacks the config framework, which means that it makes things more complex when you need all of that stuff. On the other hand, it is really fast.
I would not recommend autotools for Windows. Use CMake.
Why? Windows doesn't have a native sh.exe, and the emulation is slow. It's also very easy to get configury stuff wrong. I'm not saying it's impossible in CMake, but CMake surely abstracts more away, so you worry about less. CMake documentation can be a bit hard to read, but once it's set up, you should be fine for all toolchains ever supported by CMake. CMake also integrates testing, packaging etc...
Autotools is slow on Windows, does not work easily with MSVC, and has weird quirks with Windows (and other OSes) that are hard to debug, and hard to fix. libtool also sucks on Windows, where it often refuses to build a shared library even, if you think it should and could. Toolchain relocation issues are also prevalent with libtool, which may look at the wrong files in a user's toolchain. CMake is a lot easier in this regard. It assumes normal things about the target platform and creates generic and good build instructions.
Also, CMake has coloured output :) and nice progress percentages.
PS: I just have some experience with CMake and autotools on Windows as a user. CMake tends to work, autotools tends to bite your ear off when you're not looking, and smile at you when it fails due to some strange error...