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[Platform Notes]

# Platform Notes - VxWorks

Note: VxWorks is a community supported platform. See the Supported Platforms page for more information.

This page contains information about the Qt for VxWorks port. More information about the combinations of platforms and compilers supported by Qt can be found on the Supported Platforms page.

- Supported Versions
- Limitations
- Build Instructions
- General Notes

## Supported Versions

Qt has been tested on WindRiver VxWorks 6.7 in kernel mode using the vendor supplied GCC compiler, targetting both the x86 simulator (simpentium) and Power-PC devices (ppc). VxWorks' RTP mode is currently not supported.

## Limitations

The VxWorks kernel has an optional POSIX compatibility layer, but this layer does not implement all POSIX functionality needed for a complete Qt port.

Function | Notes
--- | ---
QProcess | Not available - VxWorks has no concept of processes.
QSharedMemory | Not available - VxWorks has only a global, flat address space.
QSystemSemaphore | Not available - VxWorks has no concept of processes.
QLibrary | QLibrary is only a small stub to make it possible to build static plugins.
QCoreApplication | Can only be instantiated once. Qt's Q(CoreE)Application is tightly coupled to one address space and process, while VxWorks only supports one global address space and has no concept of processes.
Phonon | There is no standard audio backend, which could be integrated into Phonon.
Qt3Support | The Qt3Support library is not available on VxWorks.

## Build Instructions

Qt for VxWorks needs to be cross-compiled on a Linux host. `configure` and `make` the build like you would with a standard embedded Linux cross build. Building the VxWorks simulator would be done like this:

     <path/to/qt/sources>/configure -xplatform unsupported/vxworks-simpentium-g++ -embedded vxworks -exceptions -no-gfx-linuxfb -no-mouse-linuxtp -no-mouse-pc -no-kbd-tty
     make

- `-xplatform unsupported/qws/vxworks-simpentium-g++` - selects the x86 simulator mkspec for VxWorks
- `-embedded vxworks` - builds the embedded version of Qt and sets the architecture to VxWorks
- `-exceptions` - see General Notes below
- `-no-gfx-linuxfb`, `-no-mouse-linuxtp`, `-no-mouse-pc` and `-no-kbd-tty` are Linux specific and won't work on VxWorks

## General Notes

- Configuring with `-exceptions` is necessary, because the VxWorks 6.7 g++ headers require exceptions to be enabled when compiling C++ code.
- Configure's `-xplatform` can be any of `unsupported/vxworks-(simpentium|ppc)-(g++|dcc)`, but `dcc` (WindRiver DIAB compiler) has not yet tested been tested with Qt 4.6 and VxWorks 6.7.
- Building shared libraries with `-shared` (the default) doesn't really build shared libraries, like e.g. on Linux, since these are not supported by VxWorks. Instead, qmake will created partially linked objects, that can be loaded at runtime with `ld`.
- Creating static builds with `-static` is fully supported.
- "Munching" (generating constructors/destructors for static C++ objects) is done automatically by a special qmake extension (for both shared libraries and executables)
- VxWorks does not have a file system layer, but the low level storage drivers have to supply a file system like interface to the applications. Since each driver implements a different subset of the functionality supported by this interface, Qt's file system auto-tests show wildly differing results running on different "file systems". The best results can be achieved when running on a (writable) NFS mount, since that provides the most Unix-ish interface. The worst results come from the FTP file system driver, which may crash when accessed by a `QFileInfo`.
- Keep in mind that VxWorks doesn't call your `main()` function with the standard `argc`/`argv` parameters. So either add a special `vxmain()` function or use a tool like `callmain` to translate VxWorks' commandline arguments to an `argc`/`argv` array.
- Some example will fail to build, due to some missing dependencies (e.g. shared memory) - this will be fixed in a later release.

[Platform Notes]