losing execution highlight after a few step thru while debugging

Hi guys,

I was debugging a bare metal program in DS-5 with Cortex-A15 FVP. Debugger works pretty well for the first half every time when I debug the program. But then loses source highlight on execution line. The program is alive when this happens, and still able to carry on, the only problem is no code highlight. Anybody has ideas about this.

Thanks

Below the the output from "Commands" panel in DS-5.

Execution stopped in MON mode at S:0x000101D4
S:0x000101D4   259,0   mcr p15, 4, r0, c12, c0, 0  /* HVBAR */
wait
step
Execution stopped in MON mode at S:0x000101D8
S:0x000101D8   261,0   msr cpsr_c, #0xd3                           <== still ok with line info
wait
step
Execution stopped in SVC mode at N:0x000101DC
N:0x000101DC   MOV      r1,#0x111                                  <== no line info from this point
wait
step