On 24/01/2019 00:24, Joel Sherrill wrote:
On Wed, Jan 23, 2019 at 2:01 AM Sebastian Huber
<sebastian.hu...@embedded-brains.de
<mailto:sebastian.hu...@embedded-brains.de>> wrote:
On 23/01/2019 08:11, Chris Johns wrote:
> On 23/1/19 5:50 pm, Sebastian Huber wrote:
>> On 22/01/2019 23:42, Chris Johns wrote:
>>> On 23/1/19 5:34 am, Joel Sherrill wrote:
>>>> I don't object.
>>> Is executive the right abstraction? Both terms are an
abstraction because we
>>> have a single address space and literal or formal
interpretation breaks down. I
>>> see the physical separation as an implementation detail.
>> Real-Time Executive for Multiprocessor Systems or RTEMS already
has executive in
>> its name.
> The name has evolved over time.
The M had two meanings before Multiprocessor. That's the only change.
We shall NOT
discuss the previous two since those were poor choices that biased folks.
I found the original published paper on RTEMS. It was presented in
August 1990
and the text version is at:
https://archive.org/stream/DTIC_ADA247043/DTIC_ADA247043_djvu.txt
It is clear there that kernel and executive were considered equivalent
terms.
It is also clear that operating system is used about as many times as
either
term. I did not re-read the paper to see if we used executive/kernel
to refer
to a core set of services and OS to refer to a larger collection.
https://en.wikipedia.org/wiki/Kernel_(operating_system) is an
interesting read.
Kernel is a valid term for us to use per that. A couple of quotes from
the early
part of that ignoring the IO devices mentioned. This is the first
sentence.
"The kernel is a computer program that is the core of a computer's
operating system,
with complete control over everything in the system.[1] On most
systems, it is one of the
first programs loaded on start-up (after the bootloader). "
The above matches my stated view that there is a core set of services
that support
others. The collective is the operating system. For the purposes of
this discussion,
the rtems.git repo unfortunately contains the kernel and some OS
services. So the
repo is not purely the kernel layer. It is the kernel plus core
services and libraries.
"The critical code of the kernel is usually loaded into a separate
area of memory,
which is protected from access by application programs or other, less
critical parts
of the operating system. "
The key point of the above sentence is "usually". This is in deference
to UNIX
and Windows which do have separation. The kernel is a logical
abstraction which
may have the property of separation.
This wikipedia article clearly talks about kernels that use protection
mechanisms and system calls.
Apart from that, you all seem to favour "kernel" instead of "executive".
While searching on the web I found a PDF of the Real-Time Executive for
Missile Systems C Application User's Guild.
https://apps.dtic.mil/dtic/tr/fulltext/u2/a276687.pdf
It doesn't look that much different to the current Classic API guide.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
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Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
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