Re: [Xenomai-help] Meaning of cache locking in /proc/xenomai/faults

[Axel Beierlein <belatronix@domain.hid>]

Philippe Gerum schrieb:
> On Fri, 2009-03-27 at 10:37 +0100, Axel Beierlein wrote:
>> Philippe Gerum schrieb:
>>> On Fri, 2009-03-27 at 10:00 +0100, Axel Beierlein wrote:
>>>> Hello,
>>>>
>>>> on my MPC5200 i have the following output of /proc/xenomai/faults
>>>>
>>>> TRAP         CPU0
>>>>    0:            0    (Data or instruction access)
>>>>    1:            0    (Alignment)
>>>>    2:            0    (Altivec unavailable)
>>>>    3:            0    (Program check exception)
>>>>    4:            0    (Machine check exception)
>>>>    5:            0    (Unknown)
>>>>    6:            0    (Instruction breakpoint)
>>>>    7:            0    (Run mode exception)
>>>>    8:            0    (Single-step exception)
>>>>    9:            0    (Non-recoverable exception)
>>>>   10:            0    (Software emulation)
>>>>   11:            0    (Debug)
>>>>   12:            0    (SPE)
>>>>   13:            0    (Altivec assist)
>>>>   14:  -1072753084    (Cache-locking exception)
>>>>   15:            0    (Kernel FP unavailable)
>>>>
>>>> Now i am trying to find out what the negative Value of Cache-locking and 
>>>> what this Trap general mean and when it was triggered.
>>> The negative value is only the sign of an overflow. However, a cache
>>> locking exception is specific to FSL_BOOKE archs. What is your kernel
>>> release and exact ppc platform configuration?
> 
> 
> You can ignore the last two counters, when 2.4.25-ppc is involved, they
> contain garbage in fact; this does not have any consequences beyond that
> strange output. The patch below should fix them, actually leave them
> zeroed.
> 
> --- include/asm-ppc/ipipe.h~	2008-06-08 16:15:51.000000000 +0200
> +++ include/asm-ppc/ipipe.h	2009-03-27 11:22:31.000000000 +0100
> @@ -80,7 +80,7 @@ do {						\
>  #define IPIPE_TRAP_DEBUG	11	/* Debug exception */
>  #define IPIPE_TRAP_SPE		12	/* SPE exception */
>  #define IPIPE_TRAP_ALTASSIST	13	/* Altivec assist exception */
> -#define IPIPE_NR_FAULTS		14
> +#define IPIPE_NR_FAULTS		16
>  /* Pseudo-vectors used for kernel events */
>  #define IPIPE_FIRST_EVENT	IPIPE_NR_FAULTS
>  #define IPIPE_EVENT_SYSCALL	(IPIPE_FIRST_EVENT)
> 

Thank you Philippe for your Help.

By the way, can you, or someone else, point me to a message where are 
the other traps are explained or can you give me short examples for 
situations where the listed exceptions are triggered?
For example: What is an alignment Trap and which situation can trigger 
such a fault.

Axel