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# Issues to be aware of when porting Qt/Embedded

Qt/Embedded is designed to be reasonably platform-independent. However, there is currently only a Linux implementation. The following dependencies will need to be addressed if you intend to port to another operating system (files that you need to modify are listed at the end of each section):

- System V IPC (shared memory and semaphores) is used to share window regions between client and server. You will need to provide something similar unless you want a single-application setup (i.e. running only one program, which is the server). System V semaphores are also used for synchronising access to the framebuffer.

  Modify `qwindowsystem_qws.cpp`, `qwsregionmanager_qws.cpp`, `qapplication_qws.cpp`, and `qlock_qws.cpp`.

- Unix-domain sockets are used to communicate things like keyboard events, requests to raise windows and QCOP messages between applications. Again, you will need to provide something similar unless you want a single-application setup. It should be possible to implement something like this using message queues or similar mechanisms; with the exception of QCOP messages (which are generated by client applications and not Qt/Embedded) individual messages should be no more than a few bytes in length.

  Modify `qwssocket_qws.cpp`.

- The Linux framebuffer device is used to map in the drawing area. You will need to replace it (by creating a new class of QScreen) with something else giving a byte pointer to a memory-mapped framebuffer, plus information about width, height and bit depth (which most likely you can simply hard-code). If your framebuffer is not memory-mapped or is in an unsupported format or depth you will need to modify QGfxRaster as well.

  Modify `qgfxlinuxfb_qws.cpp`.

- The accelerated drivers currently use the Linux QScreen and use /proc/bus/pci to map in PCI config space. However, these are only example drivers; the chances are that you will need to write your own driver in any case, and you will need to provide your own way to map in control registers.

  Modify `qgfxmach64_qws.cpp`, `qgfxvoodoo_qws.cpp` and `qgfxmatrox_qws.cpp`.

- Sound uses a Linux `/dev/dsp` style device. If you want to use the Qt/Embedded sound server you'll need to reimplement it.

  Modify `qsoundqss_qws.cpp`.

- select() is used to implement QSocketDevices and listen for events to/from the Qt/Embedded server application.

  Modify `qapplication_qws.cpp`.

Qt/Embedded makes use of the standard C library and some Posix functions. Mostly the latter are concentrated in platform dependent code anyway (e.g. mmap() to map in the Linux framebuffer).