Re: An RTOS without Memory Managment

On Fri, 26 Sep 2008 09:06:11 -0400, "Michael N. Moran"
<mnmoran@xxxxxxxxxxxxx> wrote:

whereas SafeRTOS (being safety critical) does not
permit dynamic memory allocation at all so these
buffers are provided statically by the application.

That´s why e.g. Sciopta handles the dynamic objects, so
their use is safe (with regard to "safety critical").

I am curious to know how having the operating system
handle dynamically created objects ensures safety,

It is just, that it seems to be a common to regard dynamic objects to
be un-safe. I believe, if the RTOS is written with saftety in mind (as
SCIOPTA is), creating and killing objects (i.e. memory or tasks, or
groups of tasks) will not impose an unsafe situtation.

Actually, the safe path must always be possible. If the (safety) RTOS
provides measures to handle this, even allocating of memory is safe.

(I am not sure if I could express it right ..., anyhow this is about
Sciopta, a DMP kernel w/o shared memory, w/o heap ... )

or prevents problems associated with fragmentation.

Sciopta uses fixed buffer pools, which does not completly remove
fragmentation, but it is known as internal fragmentation. But internal
fragmentation will not lead to an "out of memory" situations as on
returning memory, the whole buffer is available for the next
allocation.
--
42Bastian
Do not email to bastian42@xxxxxxxxx, it's a spam-only account :-)
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