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Open-Source Libraries Ease Migration From VxWorks And pSOS To Linux

Linux is hosting an ever-growing number of embedded applications. The migration of embedded applications from VxWorks and pSOS real-time Linux distributions, like Hard Hat Linux, is now a lot easier with the help of open-source porting libraries from MontaVista of Sunnyvale, Calif.

Company president and CEO Jim Ready says these libraries are designed to streamline a migration to Linux, but not automate it. They provide compatible application programming interfaces (APIs) for their respective operating systems. Migration, then, is basically a recompilation process.

VxWorks has over 1500 functions. The new Linux libraries address about 50 of these, including multitasking and scheduling functions. But standard libraries addressed by various POSIX standards already support a vast majority of the VxWorks functions. So, the number of functions Linux doesn't cover is relatively small.

Many of the VxWorks functions not included by the Linux libraries cover details that are unnecessary under Linux, such as VxWorks initialization. Since they tend to be used in a limited fashion, it's easier to make changes for migration with them than with functions that are more commonly used. The pSOS libraries similarly support migrating pSOS applications to Linux. pSOS doesn't have as many functions as VxWorks, yet the migration task will still be comparable, as it lacks 100% coverage.

The popularity of VxWorks and pSOS is well documented. But both are single-process, multithreaded operating systems where a memory management unit (MMU) is optional. Linux is a multiple-process, multithreaded operating system that normally requires an MMU. The multiple-process environment can bring up other migration issues, but this type of environment is obviously desirable in many cases. In fact, Wind River has an enhanced operating system known as VxWorks AE that's a superset of VxWorks. Many VxWorks developers will prefer the VxWorks AE approach. Others may prefer migration to Linux using these open-source libraries.

Designers may consider migration to Linux when moving applications to a new platform, especially given the preponderance of 32- and 64-bit processors being used in embedded applications. Existing platforms also are targets for a potential migration, as many 32-bit processors have been used with VxWorks and pSOS where the MMU support hasn't been fully utilized. Wind River has done an excellent job supporting and improving VxWorks and supporting pSOS, but developers now have another choice.

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