> i'm trying to decide between VxWorks and rtlinux for an RTOS project. i'd
> like hear your comments concerning vxworks if you have experience with it
> and why you're considering rtlinux.
We are trying to decide between those two, too. We haven't used either
in our products yet, but here are some of the points we have been
considering:
- We may decide to use a MIPS clone for hardware reasons. VxWorks runs
on MIPS. Linux does support MIPS, but MIPS is probably the least used
Linux platform. Moreover, RT Linux would have to be ported to MIPS
and I have no idea yet how big a task that would be (we might be
willing to pay a fee if somebody did it, though).
- AFAIK, VxWorks source code is not for sale. RTOS debugging is hard
enough with source code, so not having it may make debugging much
slower even if the bug is in our code. In addition, we may need some
special tweaks of our own that may not be possible without the source
code. The source code risk is increased by the fact that VxWorks is a
single-source product.
- With RT Linux we can place soft-RT modules in the Linux sandbox. That
means that we can add unexpected new features later without risking
the functionality of the hard-real-time core. With VxWorks, as with
most other RTOSes, new features may affect the whole system (although
I hear VxWorks offers per-task memory management as an option).
- The function and feature list of VxWorks is impressive. Personally I
find a bit risky, though, to have a single company develop and
maintain such an amount of code. Most of those functions are used by
hundred of thousands of people on the Linux side, so I tend to rely
more on the quality of Linux. For example, we may even want to run an
HTTP server on the processor -- VxWorks has it, but I'd rather run
Apache under Linux.
- RT Linux allows soft-RT-interrupts (eg, communication with the host)
to have a lower priority than critical RT tasks. I don't know if
VxWorks allows this. I'm afraid it may be difficult to estimate the
worst-case timing of VxWorks built-in device drivers.
- VxWorks is expensive.
Marko
--
Marko Rauhamaa [EMAIL PROTECTED] (818) 878-6314
Sr Project Engineer http://www.tekelec.com/ Tekelec Inc
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