User`s guide

4 Debugging Your BSP

4.3 Advanced Debugging Techniques

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execution. Most other boot loaders provide similar functionality, though the

commands may be different.

In this case, the sequence is to start the boot loader and use it to load the VxWorks

image. Next, use the OCD device to stop the processor and set the desired software

breakpoints, then resume operation. At this point, the boot loader is again

executing. Use the boot loader go command to start VxWorks. When the

breakpoint is hit, control returns to the OCD device.

Hardware Breakpoint

If available, the OCD device can set a hardware breakpoint at the RAM entry

address. The boot loader is then used to load the image into RAM and start

execution. As soon as control is given to the VxWorks initialization code, the

hardware breakpoint is encountered and the OCD device takes control. At this

point, additional breakpoints can be set using the OCD device—these breakpoints

can be either software breakpoints or hardware breakpoints.

Forever Loop

In some cases, it is most convenient to load the image the normal way, using the

boot loader load-and-go instruction, and to not use a hardware breakpoint. In this

case, it is possible to put a simple infinite loop at the beginning of the VxWorks

initialization code. After execution begins, the OCD device interrupts the

processor and takes control. At this time, breakpoints can be set at the desired

locations, and control can be returned to the VxWorks initialization code.