LCE: Realtime, present and future [LWN.net]

LCE: Realtime, present and future

Posted Nov 15, 2012 17:29 UTC (Thu) by tglx (subscriber, #31301)
In reply to: LCE: Realtime, present and future by simlo
Parent article: LCE: Realtime, present and future

I'm well aware that safety critical != hard real-time.

Though hard real-time systems must be designed in a way that they guarantee not to ever miss a deadline, simply because missing a single deadline is considered a fatal full system failure. So how do you guarantee that by other means than by mathematical proof?

> And for a practical note: The theoretical upper boundary is not magnitudes higher than what you can measure in tests.

None of those systems including Preempt-RT can specify their theoretical upper boundary, except in safe ranges which make them not at all different :)

Thanks
tglx

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Most systems also have no proof that a kernel panic won't occur.

Posted Dec 9, 2012 7:41 UTC (Sun) by gmatht (guest, #58961) [Link]

Even for a non-RT system there is usually no proof that a full system failure won't occur. E.g. Linux has no proof that a kernel panic won't occur. Systems that claim to conform to POSIX standards rarely have a proof of this. If some organisation can trace all the cases of system failure to hardware failures they may choose to trust claims made by software, including hard real time claims, without formal proof.