On Wed, 2011-04-27 at 20:42 +0200, Jean-Michel Hautbois wrote:
> Hi list,
> 
> I am currently using a Xenomai port on a linux 2.6.35.11 linux kernel
> and the adeos-ipipe-2.6.35.7-powerpc-2.12-01.patch.
> I am facing a scheduling issue on a P2020 (dual core PowerPC), and I
> get the following message :
> 
> Badness at arch/powerpc/mm/mmu_context_nohash.c:209
> NIP: c0018d20 LR: c039b94c CTR: c00343e4
> REGS: ecfadce0 TRAP: 0700   Tainted: G        W    (2.6.35.11)
> MSR: 00021000 <ME,CE>  CR: 24000488  XER: 00000000
> TASK = ec5220d0[496] 'sipaq' THREAD: ecfac000 CPU: 1
> GPR00: 00000001 ecfadd90 ec5220d0 ec5df340 ec58a700 00000000 ffffffff 00000003
> GPR08: c04a2d98 00000007 c04a2d98 0067e000 0002f385 1007f1f8 c04a5b40 ecfac040
> GPR16: c04a5b40 c04deb80 c04a2120 c04a2d98 c04a5b40 c04d008c ecfac000 00029000
> GPR24: c04d0000 c04d1e6c 00000001 ec58a700 eceaf390 c04d1e78 c0b23b40 ec5df340
> NIP [c0018d20] switch_mmu_context+0x80/0x438
> LR [c039b94c] schedule+0x774/0x7dc
> Call Trace:
> [ecfadd90] [44000484] 0x44000484 (unreliable)
> [ecfadde0] [c039b94c] schedule+0x774/0x7dc
> [ecfade50] [c039cb98] do_nanosleep+0xc8/0x114
> [ecfade80] [c0059bf8] hrtimer_nanosleep+0xd8/0x158
> [ecfadf10] [c0059d48] sys_nanosleep+0xd0/0xd4
> [ecfadf40] [c0013c0c] ret_from_syscall+0x0/0x3c
> --- Exception: c01 at 0xffa6cc4
>    LR = 0xffa6cb0
> Instruction dump:
> 40a2fff0 4c00012c 2f800000 409e0128 813b018c 2f830000 39290001 913b018c
> 419e0020 8003018c 7c000034 5400d97e <0f000000> 8123018c 3929ffff 9123018c
> 
> Do you have a clue on how to start debugging it ?

Yes, but that can't be easily summarized here. In short, we have a
serious problem with the sharing of the MMU context between the Linux
and Xenomai schedulers in the SMP case on powerpc.

> It is happening quite randomly... :).

Does disabling CONFIG_XENO_HW_UNLOCKED_SWITCH clear this issue?

> 
> Thanks in advance !
> JM
> 
> _______________________________________________
> Xenomai-core mailing list
> Xenomai-core@gna.org
> https://mail.gna.org/listinfo/xenomai-core

-- 
Philippe.



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