[ECOS] Hard-Realtime behaviour
Sun Jun 18 23:31:00 GMT 2006
On Mon, 19 Jun 2006, R Vamshi Krishna wrote:
> Now this hard real-time OS would be for use in Safety-Critical Systems. We
> would port the kernel to MISRA-C later stage but currently we are stuck-up at
> "hardening" of eCos.
Since currently most of the kernel seems to be C++, that wouldn't be
"port", that would be "rewrite". ie. If MISRA-C for the kernel is a
fixed requirement, you have lost right there.
> This guarantee I understand cannot be given by an RTOS alone. It is the
> combined guarantee by the application + RTOS. i.e. everything depends on the
> way the application was developed using the features of an RTOS.
Comment 1: Ecos has met all hard deadline requirements on our app...
Getting our code to behave has been way more problematical than Ecos.
Comment 2: Given a choice of a "harder RTOS" than ecos, "misra-c"
kernel, or a faster / smarter CPU with loads of Flash/RAM, I will take
the faster smarter CPU.
Headroom and flexibility are more important than "guarantees".
Guarantees can be broken, but headroom lets you cope with any broken
guarantees and a lot more besides.
Comment 3: Most "hard to meet hard deadlines" I have seen have been the result of
hardware designers saying "lets skimp a bit and fix it in the software".
So if you have a really hard hard to meet RT deadline, walk over to your
hardware designers and talk to them about life, the universe, safety and
John Carter Phone : (64)(3) 358 6639
Tait Electronics Fax : (64)(3) 359 4632
PO Box 1645 Christchurch Email : firstname.lastname@example.org
Carter's Clarification of Murphy's Law.
"Things only ever go right so that they may go more spectacularly wrong later."
>From this principle, all of life and physics may be deduced.
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