RT-Control questions

Der Herr Hofrat der.herr at mail.hofr.at
Fri Aug 9 20:06:57 CEST 2002

> > RTLinux/GPL ist still under development and will stay there - there is a
> > comercial version under development but that does not prevent anybody 
> > from developing RTLinux/GPL - for a quite complete list of available
> > patches/bugfixes and updates to current kernels (2.4.16/18/19 UP and SMP)
> > check at 
> > 
> >    http://www.fsmlabs.at/rtlinuxgpl.html   and 
> (1) It is ridculous to patch a patch for the linux kernel. If I download
>  I want it to run with a current and stable linux kernel version, which would be 2.2.18 by now.

Well thats the way most things evolve first its a patch and when we have
enough testing then we package it up to rtlinux-3.2 - you might think 
thats a bad way to do it buts thats the comon practice - and if you think
its rediculous to patch patched kernels then 90% of the non-X86 development
is very rediculous ....linux-2.4.18-rmk1-np1-ads5-rtl ...thats a patch^4 ,
a very rediculous arm board of mine with a cool brail display and by far the
most stable braille system I ever had ;)

> (2) Good documentation is also a must. I am quite happy with what RTAI provides yet.

fine - if you want to contribute some docs to rtlinux - or atleast tell the comunity what you are missing then there might be a posibility of pointing you to the right location - did you give rtldoc-3.1.tar.gz a look ?? RTLinux/GPL is based on a POSIX PSE 51 API if you know how to write POSIX code then you realy have all the docs you need - there are many good books on POSIX and there are a number of references to the single unix specs V2 for details (and... there still are man pages....)

> (3) A commercial rt-linux based system does not fit into the open-source and open-development idea of linux. 

If that were the case a substantial portion of the linux development would not
fit into the idea of linux - what do you think a s390 port is ? the product of
some hardware freaks spending the nights in the basment of there houses hacking
away at there private s390 "desk-top" ? most of the porting effort were done 
for commercial resons and RTAI aswell as RTLinux is primarily in use in 
comercial application (I personally don't know of anybody using it on his 
desk-top system for anything else but to play with - it IS a comercial 
product well fited into the linux project - no matter if you take the GPL 
version or any non-GPL version). The GPL is not a non-comercial effort, the
GPL is about keeping technology open - or to say it the way RMS states it 
over and over again - GPL is about freedom not free beer - see www.gnu.org .

> If I have to go with a commercial system I can also buy QNX and the likes. Why choose RT-Linux then?

Right - but RTLinux/GPL is not a commercial system so whats the problem ?
compare the performance and if you think QNX does better and
supports your comondity-component-PC better then use QNX - nobody
if forcing you to use RTLinux RTAI RED KURT low-latency or a 
preemtive 2.5.X (or patched-patched 2.4.X ;) for your project.

> (I am not sure, but as far as I can remember QNX is free for educational purposes!!!)

that is in part true - but did you ever try to write a device driver for QNX ?
or change some core part - or add to it because you find a way to improve ?
well that is what the open source comunity lives from - if you don't like that
then buy a comercial RTOS and work with that - fine with me.

RTLinux/GPL is a community project if you want to have a complete redy to run
system and don't intend to contribute anything then you probably will be
happier with a commercial RTOS - I realy don't see what the point of fussing
at me is, that is within the nature of GPL efforts that they at cirtain 
points in time are incomplete, if you don't like that way of working then
the GPL-world may well not be for you.


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