Using GDB - 2021.2 English

Versal ACAP AI Engine Programming Environment User Guide (UG1076)

Document ID
UG1076
ft:locale
English (United States)
Release Date
2021-12-17
Version
2021.2 English

After successful compilation with the appropriate target you can launch the simulation and automatically attach a GDB instance to it. To launch an interactive GDB session run the command with the switch --gdb as follows.

x86simulator --gdb

By default, when running the x86 simulator with the --gdb command line switch it breaks immediately before entering main() in graph.cpp. This pauses execution before any AI Engine kernels have started because the graph has not been run. To exit GDB type quit or help for more commands.

Setting a breakpoint can be done in multiple ways. One method is to use the following syntax.

break <kernel_function_name>

By typing continue (shorthand c) the debugger runs until the breakpoint in <kernel function name> is reached. When the breakpoint is reached it is possible to examine local stack variables and function arguments. The following table shows some commonly used GDB instructions to allow examination of these variables.

Table 1. Common GDB Instructions
Command Description
info stack Reports the function call stack at the current breakpoint.
info locals Shows the current status of local variables within the scope of the function call shown in the call stack.
print <local_variable_name> Prints the current value of a single variable.
finish Exits the current function call but keeps the simulation paused.
continue Causes the debugger to run to completion.

GDB is a very powerful debugger with many features. Complete documentation of GDB is beyond the scope of this document. For GDB documentation, see https://sourceware.org/gdb/current/onlinedocs/gdb.pdf and https://sourceware.org/gdb/current/onlinedocs/refcard.pdf.