[vdr] Re: Annoying EMERGENCY EXITs

[Rene Bartsch <ml@bartschnet.de>]

Oliver Endriss schrieb:

> vdr could monitor the card health reported by the driver. If an error 
> occurres, vdr would reset the card in question, re-tune and set all 
> filters again. No need to unload/reload everything.
> I'm aware that this means a lot of work on the driver, but I think it 
> should be possible. Could vdr handle it this way?
I agree to Oliver here. You have two things determining stability of a 
software a) functions and b) data. It's the author's task to implement 
bug-free functions and to catch errors. This is mostly done in VDR 
(Thanx to Klaus! :o) ).

But you cannot influence the quality of data you get from another module 
(DVB-driver). So the only way to keep your software stable is to reject 
invalid data (The golden rule for a stable module is to only accept 
valid data and only provide valid data to the next module). This means 
VDR should use the watchdog to keep itself running and simply disable 
cards temporary which do not provide valid data (e.g. by checking stream 
and/or signal-strengh).

Recovering hardware errors should be task of the driver, which means the 
driver has to keep arrays with the registers for each card. If registers 
are changed, this won't be done on hardware but in the array. After each 
change - or reset - the complete arrays have to be transferred for each 
device. So the driver could reset each card without disturbing others.

> > > In case one card fails but enough cards are left for recording, VDR
> > > also shouldn't restart but wait for the recordings to end.
> > As far as I can see emergency exits are only done if an ongoing
> > recording is having trouble. So it makes no sense to me _not_ to do
> > an emergency exit if recording A is having trouble on card 1, just
> > because recording B is running fine on card 2. I'd rather have a
> > short glitch in recording B and still get the rest of recording A
> > than have an uninterrupted recording B and miss half or all of
> > recording A.
What about moving recording A dynamically to card 3?
What for do we have a tux-based VDR if not for free scaling of hardware?

> Well, I think there are people who would rather have one good recording 
> without glitches than two recordings with glitches. It's a matter of 
> taste. Maybe error recovery strategy could be a setup option in 1.3.x?
>
> Oliver
I agree here. One good recording is better than two recordings with at 
least 20 seconds missing for each restart.

Rene



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