User guide

GUI Reference

Trace View (Debug Perspective)

You open this view from the Debug perspective by pointing to Show View on the Window

menu, and then clicking Trace.

The Nios II IDE Trace view displays a disassembly trace of the instructions executed prior to

the current breakpoint or watchpoint, and optionally displays load/store addresses and the

associated data. The Trace view allows you to analyze execution details that are not available

in the source disassembly listing, such as branches taken at runtime, and precisely when

exceptions occurred.

The Trace view is only available in the Debug perspective, and does not automatically display

as part of the Debug perspective. The Trace view only functions when debugging Nios II

hardware targets. If the hardware does not support trace, then the Trace view does not

function. The JTAG debug module on the target processor must be configured to support trace

collection.

During a debug session, the Trace view automatically displays trace data whenever processor

execution suspends. The most recently executed instruction displays at the bottom of the

view.

The Trace view displays the following information:

Address of the instruction in hex

C/C++ function containing the suspended instruction, plus a (hex) offset

The instruction word in hex

Disassembly of the instruction word

Load and/or store addresses, and associated data (depending on trace preferences)

Ellipses in the disassembly indicate that the JTAG debug module might have dropped some

instructions while collecting trace data. The trace might not be reliable at that point. The

following disassembly is an example.

0x01000068 <foo+0x24>: 0xdec00204 addi sp, sp, 8

...

0x0100006c <foo+0x28>: 0xf800283a ret

Note: FS/2 must be disabled in the Debug dialog box in order for native trace to work.