MMU

[Matthew R Wette]

MMU is used (e.g., in space applications) to provide the capability 
to map out bad blocks of memory.

Charles-Antoine Gauthier writes ...
> RTEMS is meant for hard real-time systems. Such systems do not do demand
> paging because of the phenomenally high cost of fetching pages from disk
> (relative to CPU speeds). Virtual memory may still be used. In some BSPs
> with caches, the MMU is usually set up "to stay out of the way" as Joel
> puts it, but it must be programmed to control the cache. Either some
> form of block address translation is used, or page descriptors must be
> set up.
> 
> One could also imagine setting up virtual addressing to build a flat
> address space multiprocessor where each board uses the same fixed
> physical addressing, as is common with many VME cards (IMHO usually due
> to brain-damaged CPU designs).
> 
> Joel Sherrill wrote:
> > 
> > "Boris V. Guzhov" wrote:
> > >
> > > Hi All!
> > >
> > > Is there any sopport of the MMU in the RTEMS?
> > 
> > Only in the sense that some BSPs initialize MMUs
> > to stay out of the way.
> > 
> > On a single CPU, RTEMS supports a POSIX model
> > of a process with multiple threads.
> > 
> > This is a useful features that is critical for
> > some embedded application classes.
> > 
> > > Boris V. Guzhov,
> > > St.Petersburg
> > 
> > --
> > 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
> 
> -- 
> Charles-Antoine Gauthier
> Institute for Information Technology   Institut de technologie de
> l'information
> National Research Council of Canada    Conseil national de recherches du
> Canada