> Hello all,
>
> I'm hoping to move our next-generation products to a StrongArm/embedded
> Linux platform but have met resistance from some who contend that
> Linux cannot be used as an RTOS. I understand that Linux cannot
> complete directly with the likes of a real RTOS, say from Pharlap,
^^^^^^^^
= compete?
> but if your RTOS requirements are minimal, the advantages of
> having an open-source based system, with the huge amount of
> software available, outweigh the RTOS deficiencies of Linux.
Cygnus has apparently just released their eCOS RTOS
--- it was developed a few years ago; and they've been
trying to release it to GPL to follow the mainstream of
their business model; but they were held up by some of their
business associates.
Look at the Cygnus web site for details.
> With an embedded Linux, I assume you can still service your
> interrupt routines without having to make system calls. Please
> correct me if I'm wrong.
> So, any thoughts about Linux as an RTOS?
Personally I still think that Linux is a pretty silly choice
for *embedded* systems. I think its an excellent choice
for turnkey systems (info appliances, X and ether terminals,
NC's, vertical systems like "lanalyzers" that sort of thing).
However, I'm probably splitting hairs in a field that has
long since blurred the distinction that I'm thinking of.
I think of "embedded" OS' as things that are measured in K
or 10's of K. Hundreds of kilobytes and megabytes are a
different realm.
Nonetheless the real-time factor is a bit of a red herring.
There are RT patches for Linux. There are also some
alternative bits of scheduling code that various people have
played with --- and some of these have been discussed
extensively on the kernel mailing list.
(There was some talk of a dual run queue that apparently
gave pretty good "soft real-time" performance, suitable for
playing MPEG's, audio and IP telephony).
So, you have some choice that are already out there (some in
the form of unofficial kernel patches. More importantly you
have considerable evidence that the structure of the kernel
sources makes it feasible for a good programmer to
experiment with and implement their own schedulers, and to
run the entire Linux kernel under any number of microkernels
(RTLinux implements a minimal mk and runs Linux as the major
"idle time" task under it; additionally version of Linux
have been modified and run under the Mach, L4, and L5
microkernels).
> Thanks,
> Chuck
--
Jim Dennis (800) 938-4078 [EMAIL PROTECTED]
Proprietor, Starshine Technical Services: http://www.starshine.org
