RTAI/RtLinux

[Erwin Rol <erwin@muffin.org>]

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Normally I am not subscribed to the kernel list, but after a msg from
Karim that there was a "fight" going on about RTAI I read the archives
and decided that it was important enough to join the discussion.

Both Linus and Larry seem to be not very interested in hard-realtime
Linux additions, this is OK. I mean everybody has his interests and with
so many Linux users and developers you can't all focus on the same
thing.

But we (RTAI developers, which include Karim and myself) have decided to
focus on hard-realtime extensions to Linux. And it is than always very
motivating to hear nobody gives a f*ck about your work or problems,
because "hey, you don't have a business model that makes sense anyway"

For example, first there is said that there is no userspace
hard-realtime, than Karim corrects that, than there is said that a
userspace program that uses mlockall is actually a module: with other
words be quiet and go sit in the corner.
This seems the same as what happened with  FSMLabs, first they explain
why userspace hard-realtime is crap, and now they have implemented it
them self and explain how good it is. 

We have had several discussions with FSMLabs about userspace
hard-realtime and asked for comments on for example the following
situation.

-
When i write a RTAI module, that changes the sched_setparam in such a
way that SCHED_FIFO and SCHED_RR are now hardrealtime. Than a binary
program that runs on a computer with the RTAI kernel-module loaded
violates the patent, and on a computer that doesn't have it loaded it
doesn't violate the patent. 
-
needless to say we never even got a reply on questions like these. When
you have to believe FSMLabbs, you are not allowed to use non-GPL
software on a system that has a RTAI module loaded, according to Eben Mo

There was also asked about the possibility (and even some person on the
RTAI list started such a project) to have a *BSD version of RTAI, well
the answer is simply NO. since *BSD will not accept GPL kernel code, and
the RTLinux patent doesn't allow no GPL implementations there will be no
free *BSD with this type of hard-realtime. Of course you can buy the
FSMLab version, but than you can just as well buy a true RTOS, like
VxWorks.

Also apparently there is the idea that all RTAI developers want to
become rich by getting the patent out of the way and sell RTAI. I know
you all know this is simply not true, like most Linux hacker we spend a
large part of our free time to give the real-time community a usable
piece of software where they normally have to pay for. 
So please don't stamp us as some money sucking bastards that shouldn't
be allowed to use Linux in the first place.

I just hope the linux developers are smart enough to not accept the
RTLinux into the main kernel, cause someday someone might come up with
the idea to write something that allows to have userspace programs to be
hard-realtime, and than you have to stop allowing non GPL userspace
programs, like for example GLIB( which is LGPL). 

- Erwin Rol , RTAI Developer






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