Data storage interrupt invoked for MPC5604b on execution of lwzx

[pradeepmc]

Hi,
Needed some help with an issue where Data storage interrupt is being invoked on execution of lwzx instruction.

I am using the following Codewarrior 10.7 evaluation edition.
Target MCU is MPC5604B

The following default settings are ON for the project:
c/c++ build -> settings -> PowerPC CPU -> Processor is set to ZEN (I cant find e200z0h core)
c/c++ build -> settings -> PowerPC CPU -> Compress for PowerPC VLE (zen)
c/c++ build -> settings -> PowerPC Compiler -> Processor -> Translate PPC ASM to VLE ASM (ZEN)

 On execution of the below code, Data storage interrupt is generated.
I did a step execution on the disassembled code and see that lwzx is the instruction causing the interrupt.

Disassembled code:

2064                  if( listCURRENT_LIST_LENGTH( &( pxReadyTasksLists[ pxCurrentTCB->uxPriority ] ) ) > ( UBaseType_t ) 1 )
40001aca:   e_lwz r3,0(r22)
40001ace:   se_lwz r0,44(r3)
40001ad0:   e_mulli r9,r0,20
40001ad4:   e_lis r8,0x4000
40001ad8:   e_add16i r8,r8,19464
40001adc:   lwzx r0,r8,r9
40001ae0:   se_cmpli r0,0x0001
40001ae2:   se_ble xTaskIncrementTick+0xf0 (0x40001ae6); 0x40001AE6

The assembly code is generated by the compiler.
The above code is part of an ISR.

As per the BOOK E reference manual:
checked the Excection syndrome register.

ESR    0x00000021    $ESR

Only below fields are set. Not sure what to do with this data.

   VLEMI =1

   XTE=1

Any help would be appreciated.

Regards,
Pradeep M C

[davidtosenovjan · Accepted solution]

Hi, XTE marks External Termination Error.

Typically it can be caused by

- ECC error  

- accessing of reserved memory

- accessing of unimplemented register

- accessing of peripheral registers that is turned off

- can be asserted by EBI bus monitor if enabled

[pradeepmc]

Thanks David.

Yes, it is because of the accessing of reserved memory.

I checked the DEAR register and the address was some invalid value.

I was able to fix the logical error in my code.