[Xenomai-core] rare brokenness in latency output - FPU bug!

[Jan Kiszka <jan.kiszka@domain.hid>]

[-- Attachment #1.1: Type: text/plain, Size: 1812 bytes --]

Hi,

it's now the second box I noticed this minor quirk with SVN head:
latency (tested with -t0 only so far) sometimes gives me a broken "lat
worst" number like this:

> RTD|      15.637|      17.842|      42.750|       0|       4.601|      54.264
> RTT|  00:04:55  (periodic user-mode task, 100 us period, priority 99)
> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
> RTD|      14.463|      18.019|      41.907|       0|       4.601|         nan
> RTD|      15.197|      17.902|      37.396|       0|       4.601|      54.264

I also already had weird large numbers here (>200 digits) which makes me
think that this is not an issue of gmaxj (local long variable to store
the result before output conversion), but rather something with the FPU.
Anyone any thoughts?


Uhh, wait! I just fired up switchtest on the same box:

> == Testing FPU check routines...
> r0: 1 != 2
> r1: 1 != 2
> r2: 1 != 2
> r3: 1 != 2
> r4: 1 != 2
> r5: 1 != 2
> r6: 1 != 2
> r7: 1 != 2
> == FPU check routines: OK.
> == Threads: sleeper_ufps-0 rtk-1 rtk-2 rtk_fp-3 rtk_fp-4 rtk_fp_ufpp-5 rtk_fp_ufpp-6 rtup-7 rtup-8 rtup_ufpp-9 rtup_ufpp-10 rtus-11 rtus-12 rtus_ufps-13 rtus_ufps-14 rtuo-15 rtuo-16 rtuo_ufpp-17 rtuo_ufpp-18 rtuo_ufps-19 rtuo_ufps-20 rtuo_ufpp_ufps-21 rtuo_ufpp_ufps-22
> r0: 2147483648 != 10
> r1: 2147483648 != 10
> r2: 2147483648 != 10
> r3: 2147483648 != 10
> r4: 2147483648 != 10
> r5: 2147483648 != 10
> r6: 2147483648 != 10
> r7: 2147483648 != 10
> Error after context switch from task 8(rtup-8) to task 10(rtup_ufpp-10),
> FPU registers were set to 2147483648 (maybe task ???)
> Segmentation fault

Gilles, what info do you need? It's all the latest on x86 here:
2.6.17.13 (.config attached), ipipe-1.4, SVN #1646, gcc4.1.0.

Jan

[-- Attachment #1.2: config-2.6.17.bz2 --]
[-- Type: application/octet-stream, Size: 7132 bytes --]

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 250 bytes --]