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3.8   Differences Between VxWorks and Host System I/O

Most commonplace uses of I/O in VxWorks are completely source-compatible with I/O in UNIX and Windows. However, note the following differences:

  • Device Configuration. .  
    In VxWorks, device drivers can be installed and removed dynamically.

  • File Descriptors. .  
    In UNIX and Windows, fds are unique to each process. In VxWorks, fds are global entities, accessible by any task, except for standard input, standard output, and standard error (0, 1, and 2), which can be task specific.

  • I/O Control. .  
    The specific parameters passed to ioctl( ) functions can differ between UNIX and VxWorks.

  • Driver Routines. .  
    In UNIX, device drivers execute in system mode and are not preemptible. In VxWorks, driver routines are in fact preemptible because they execute within the context of the task that invoked them.

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