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

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

The following reply was made to PR port-arm/52603; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: port-arm-maintainer%NetBSD.org@localhost, gnats-bugs%NetBSD.org@localhost,
        netbsd-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: port-arm/52603: arm(v7?) vfp register corruption
Date: Wed, 11 Oct 2017 15:00:06 +0200

 I tested on a RPI3, running
 ./fptest 5
 shows the problematic behavior much faster here: in less than a minute
 I got more than 30 failures:
 
 $ ./fptest 5                                                            [34/130]
 start job 0 for 32 registers        
 start job 2 for 32 registers        
 start job 3 for 32 registers        
 start job 4 for 32 registers        
 start job 1 for 32 registers        
                                     
 5: 205.500000 205.500000 205.500000 
                                     
 7: 107.700000 0.000000 107.700000   
 16: 117.600000 105.500000 117.600000
 17: 118.700000 105.500000 118.700000
 18: 119.800000 100.000000 119.800000
 19: 120.900000 1.100000 120.900000  
 0: 400.000000 100.000000 400.000000 
 1: 401.100000 101.100000 401.100000
 2: 402.200000 102.200000 402.200000
 3: 403.300000 103.300000 403.300000
 4: 404.400000 104.400000 404.400000
 5: 405.500000 105.500000 405.500000
 6: 406.600000 106.600000 406.600000
 7: 407.700000 107.700000 407.700000
 8: 408.800000 108.800000 408.800000
 9: 409.900000 109.900000 409.900000
 10: 411.000000 111.000000 411.000000
 11: 412.100000 112.100000 412.100000
 12: 413.200000 113.200000 413.200000
 13: 414.300000 114.300000 414.300000
 14: 415.400000 115.400000 415.400000
 15: 416.500000 116.500000 416.500000
 16: 417.600000 117.600000 417.600000
 17: 418.700000 118.700000 418.700000
 18: 419.800000 119.800000 419.800000
 19: 420.900000 120.900000 420.900000
 20: 422.000000 122.000000 422.000000
 21: 423.100000 123.100000 423.100000
 22: 424.200000 124.200000 424.200000
 23: 425.300000 125.300000 425.300000
 24: 426.400000 126.400000 426.400000
 25: 427.500000 127.500000 427.500000
 26: 428.600000 128.600000 428.600000
 27: 429.700000 129.700000 429.700000
 28: 430.800000 130.800000 430.800000
 29: 431.900000 131.900000 431.900000
 30: 433.000000 133.000000 433.000000
 0: 100.000000 417.600000 100.000000
 3: 103.300000 0.000000 103.300000
 4: 104.400000 10.000000 104.400000
 5: 105.500000 0.500000 105.500000
 6: 106.600000 0.500000 106.600000
 7: 107.700000 0.000000 107.700000
 16: 117.600000 417.600000 117.600000
 17: 118.700000 400.000000 118.700000
 18: 119.800000 1.100000 119.800000
 19: 120.900000 1.100000 120.900000
 
 The first one is strange, it looks like registers have the correct values,
 yet the compare failed.
 
 I looked at subr_pcu.c and vfp_init.c but I didn't see anything obvious ...
 I added a few KASSERT() in both files but they didn't fire.
 
 idea welcome ...
 
 -- 
 Manuel Bouyer <bouyer%antioche.eu.org@localhost>
      NetBSD: 26 ans d'experience feront toujours la difference
 --