[okl4-developer] hardware debugging support added in traps.spp leads to OKL4 crash

[Gabi Voiculescu]

Hello.

I am trying to add hardware debugging support to OKL4-2.1.0. on my ARM1176 development chip processor (the debugging hardware is present and working).

I achieve this by filling with a task specific, non-zero value the PROCID bitfield of the ContextID  register (p15, 0, xxx, c13, c0, 1) in traps.spp.

Reading the ARM documentation and interacting with ARM technical support I was assured that the PROCID bitfield has no impact on the memory management unit, being just useful for hardware debugging.

When using my modified traps.spp, OKL4 freezes.


Questions:

Do you have any previous experience with this particular functionality?

Can you give me a hint on why my two instructions could lead to an OKL4 crash?

Can you help me in fixing this?

Thank you,
Gabi Voiculescu
Newgate Design



Below I give the diff output.
------------------------------------------------------------------------------
$ diff traps.spp traps.spp.gabi
649c649,655
< 
---
>         
>         ldr     tmp1,   [to_tcb, #OFS_TCB_MYSELF_GLOBAL]
>         
>         
>         add     tmp2,   tmp2,   tmp1,   lsl #8*/  /* CHECKME: tmp2 = tmp2 + (tmp1<<8) -gabi */
>         
>          
651c657
<         mcr     p15, 0, tmp6, c13, c0, 1
---
>         mcr     p15, 0, tmp6, c13, c0, 1 
1486c1492,1497
< 
---
>         
>         ldr     tmp1,   [to_tcb, #OFS_TCB_MYSELF_GLOBAL] 
>         
>         
>         add     tmp2,   tmp2,   tmp1,   lsl #8*/    /* CHECKME: tmp2 = tmp2 + (tmp1<<8) -gabi */








      
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