What does CMAKE_EMULATOR emulate? >From its name, it sounds like it emulates CMake. But from your description, I'm thinking that doesn't make sense... Because you actually run CMake and pass it CMAKE_EMULATOR. So it must be emulating something else while running CMake?
I'm guessing it emulates the target system when cross-compiling, and executables built for the target system can be run when passed to the emulator? Is that right? D On Wednesday, March 4, 2015, Matt McCormick <[email protected]> wrote: > Hi, > > I have pushed to stage [1] support for a CMAKE_EMULATOR variable to > help when cross-compiling. The goal is to improve cross compiling > with CMake by making it easier to build and run tests. In principle, > the commands > > cmake -DCMAKE_TOOLCHAIN_FILE=/path/to/toolchain.cmake > -DCMAKE_EMULATOR=/path/to/emulator ~/src/project > cmake -D Experimental > > are all that is needed generate a dashboard report, complete with test > results. This should inch C/C++ closer to being the "write once, run > anywhere" languages :-). > > The emulator is used to run try_run results, which avoids manual > population of TryRunResults.cmake. This can be a painful, > time-consuming process otherwise. > > It is also used to run tests on executables that are built for the > target system. Without this approach, it is difficult to know which > tests should be executed on the target system. Tests are often passed > absolute paths to input on the host system. The use of an emulator is > a way to avoid complexities and transfer overhead related to > reproducing the host filesystem on the target filesystem to run the > tests. > > > With some fixes to ITK [2], this was used to build and test for four > cases of interest. > > The emulator approach works best with MinGW and WINE to build and test > on Linux for Windows [3]. > > The qemu-arm emulator provided by QEMU User Mode can be used with the > Android NDK toolchain [4]. A gotcha is that Android tries to be fancy > and uses its own dynamic loader. To get around this, I tested with > completely static executables. Also, QEMU User Mode does not > currently support multi-threading well, so tests were run > single-threaded. An alternative approach may be to use an emulator > script that is a wrapper around adb. > > The qemu-arm emulator was used again with the Raspberry Pi toolchain > [5]. A symbolic link was created in the expected location for > ld-linux-armhf.so.3, and dynamic loading works. To run the tests, > LD_LIBRARY_PATH was populated with the path to libc and libstdcxx. > > One of the most interesting combinations is the Emscripten toolchain > with NodeJS as the emulator [6]. There are some WIP workarounds to get > Emscripten to configure cleanly for scientific libraries [7], and code > had to be injected into the test driver to mount local filesystems for > node, but this works surprisingly well. > > > Testing and feedback are appreciated. > > Thanks, > Matt > > > [1] > http://www.cmake.org/gitweb?p=stage/cmake.git;a=shortlog;h=refs/heads/emulator > > [2] https://github.com/thewtex/ITK/tree/cmake-emulator > > [3] https://open.cdash.org/buildSummary.php?buildid=3694578 > > [4] https://open.cdash.org/buildSummary.php?buildid=3694810 > > [5] https://open.cdash.org/buildSummary.php?buildid=3694810 > > [6] https://open.cdash.org/buildSummary.php?buildid=3705525 > > [7] https://github.com/thewtex/emscripten/tree/test-big-endian > -- > > Powered by www.kitware.com > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Kitware offers various services to support the CMake community. For more > information on each offering, please visit: > > CMake Support: http://cmake.org/cmake/help/support.html > CMake Consulting: http://cmake.org/cmake/help/consulting.html > CMake Training Courses: http://cmake.org/cmake/help/training.html > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Follow this link to subscribe/unsubscribe: > http://public.kitware.com/mailman/listinfo/cmake-developers >
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