Re: port-arm/52603: arm(v7?) vfp register corruption

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sun, Oct 08, 2017 at 04:20:00PM +0000, bouyer%antioche.eu.org@localhost wrote:
> 	running 
> ./fptest 2
> 	in parallel with opencpn, after a few hours I got
> 0: 100.000000 100.000000 28.000000
> 
> 	and then, less than a day later:
> 0: 100.000000 11.672723 100.000000
> 1: 101.100000 16.850291 101.100000
> 2: 102.200000 6.424029 102.200000
> 3: 103.300000 16.679222 103.300000
> 4: 104.400000 255.000000 104.400000
> 5: 105.500000 255.000000 105.500000
> 6: 106.600000 255.000000 106.600000
> 7: 107.700000 0.002048 107.700000
> 8: 108.800000 0.087582 108.800000
> 9: 109.900000 0.500000 109.900000
> 
> 	so we have rare but obvious vfp register corruption.
> 	I suspect it's related an to interrupt occuring at the wrong
> 	time, but couldn't track it down more than that.

running
./fptest 3
without opencpn, on an otherwise idle board didn't show corruption after
24h. But starting a ping -f against the board caused the corruption to
show up in less than half an hour.

So it looks like interrupt activity (other than the CPU ticks) is needed to
trigger the problem.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--