[leon_sparc] Re: another, rtems vs rest?

[Joel Sherrill]

The LEOX team wrote:
> 
> Hi Joel,
> 
> Really pleased to hear something from you on the leon_sparc mailing list.
> I would like to know if it exists documentations describing the internal
> architecture of RTEMS?

There is a document describing the process of porting to a new CPU
family.  There is also another document describing the BSP and
Device Driver construction process.  As far as a good architectural
picture of how the APIs are layered on top of the SuperCore which is
in turned layered on the hardware abstraction layer, there really isn't
anything suitable for distribution.

I have always wanted to write a book on the Design and Implementation
of RTEMS but have never gotten time to do it.  I would love to get
a paid invited gig at a conference or workshop and cover the 
RTEMS architecture.  I have a great starting point for a 1/2 to 1 day
tutorial on it.  I included it in a graduate real-time class I
taught a few years ago but I really would like to clean it up
and add more figures and details.

--joel

> Many thanks for your collaboration.
> 
> Quoting Joel Sherrill <joel.sherrill at OARcorp.com>:
> 
> >
> >
> > "J.Saravanan" wrote:
> > >
> > > Hi,
> > >
> > > Well, I've a beginners question (in rtos world).
> >
> > Well since I haven't seen a reply yet, I'll take a quick swing.
> >
> > > I understand RTEMS is an RTOS and is most suitable for control
> > > applications. It can be seen that (from mailing list archive) RTEMS
> > can
> > > also be used for non-RTOS purpose, with a small shell and few
> > applications
> > > that are statically linked.
> >
> > Yes.
> >
> > > My question is, If time is not critical then what prevents from
> > using
> > > RTEMS as general purpose OS, just like linux. I believe, one cannot
> > link
> > > too may applications in an RTOS like in general purpose OS. Is that
> > > correct? Then what is the knee point?
> >
> > Right now, the lack of dynamic loading is the biggest lacking for
> > usefulness.  There has been work on a dynamic loader but I don't
> > know the precise status of it at the moment.
> >
> > The lack of memory protection is a liability but there have
> > certanly been plenty of general purpose OSes without that.
> >
> > > (Assuming RTEMS and the rest has all the facilities available, like
> > > library, etc.)
> >
> > It has programming libraries but is lacking in graphics
> > and device driver support in comparison to GNU/Linux.
> > If you were constructing a PDA based upon RTEMS that would
> > be OK, since you would settle on a single graphics
> > standard and hardware configuration but desktop computing
> > is way too varied.
> >
> > > Thanks,
> > >
> > > Regards,
> > > -Saran
> >
> > --
> > Joel Sherrill, Ph.D.             Director of Research & Development
> > joel at OARcorp.com                 On-Line Applications Research
> > Ask me about RTEMS: a free RTOS  Huntsville AL 35805
> >    Support Available             (256) 722-9985
> 
> Best Regards
> The LEOX team
> 
> http://www.leox.org : Free Hardware and Software Resources for System-on-Chip

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
Support Available                (256) 722-9985