GNU debugger

GNU debugger

cheat sheet (nonexhaustive)

commands can be shortened

e.g.: b for breakpoint

command	description
`continue`	continue normal execution
`break <position>`	set breakpoint
`info breakpoint`	list breakpoints
`delete <#breakpoint>`	delete breakpoint
`step`	execute next instruction, then halt (step in)
`next`	execute next instruction (step over)
`finish`	execute until the end of the current function (step out)

`backtrace`	show call stack
`print[/format]`	show content of variable/memory location/register
`x[/format] address`	print memory content at address
`list <position>`	show file/lines/symbol in source code window

`tui disable`	disable tui
`tui enable`	enable tui
`layout <layout>`	select specified layout
`layout next/prev`	choose next or previous layout
`focus <window>`	focus specified window

position	description
`<symbol-name>`	name of a symbol, e.g. function name
`<line>`	line number (in current file)
`<file>:<line>`	line number in the specified file

reset program

To reset the program one can use the following command

# reset program and halt execution
monitor reset halt

TUI mode

The GDB comes with a Terminal User Interface (TUI) which provides view for the assembly, the registers and the source code.

One can enable the TUI with tui enable or disable with tui disable.

# enable/disable TUI
tui enable
tui disable

TUI keybindings

Keybinding	Action
`C-x,a/A/C-a`	toggle TUI mode on/off
`C-o`	focus next window

One can navigate using the keybindings, but the easiest method is to use the focus command. The cmd window is the only one that accepts alphanumeric input, so regardless of the focused window, one can always use focus <window> to focus a specific window.

layouts

One can choose various layouts with the following command:

# choose layout, enable views
layout <layout-name>
# default layout options:
# * asm
# * regs
# * src
# * split

The tui command also allows to define custom layouts. See the example below.

# defines a layout with the name `test` and the view `regs`, `src` and `cmd`
tui new-layout test {-horizontal regs 1 src 2} 1 cmd 1

# synopsis of `tui new-layout`
tui new-layout <name>  <view> <weight> [<view> <weight>]
tui new-layout <name> {[-horizontal] <view> <weight> [<view> <weight>]} <weight>

source code view

The source code view - as the name suggests - displays source code. By default the window displays the file containing the current instruction, but one can choose a differnt file with the list command. Below are several examples of how to use this command.

# when specifying a file, a line number is required
list <file-name>:<line-number>

# list knows symbol names
list <symbol>
list main # this will show the main function

# show current execution point
list .

4.0 KiB Raw Blame History