path: root/documentation/GDB commands

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###			GDB COMMANDS				###
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QEMU CONFIGURATION

	qemu must be started with "-s" option
	(shorthand for "-gdb tcp::1234")

#
# GDB PART 
#

SYMBOL FILES
	add-symbol-file /path/to/Hello.debug 0x... -s .data 0x...


CONNECTION
	- source gdbscript 
		(if a gdbscript is created, which contains
		add-symbol-file commandos)

	- target remote localhost:1234

DISCONNECTION
	- detach
		break connection with target, target resumes execution
		GDB				Target
		(RSP Client)			(RSP Server)
				D
		O------------------------------>O
						O RSP exchange
		O<------------------------------O
				OK
	-disconnect
		Simply break connection. Target stays at the point where execution terminated previously
		Reconnection(target remote): resume debugging at the point where the previous connection was broken

BREAKPOINTS

	- b CoreHandleProtocol 	|| or OutputString
	- break *0x65fe447	|| set breakpoint at address
	- delete 2		|| delete breakpoint no 2
	- break sampleApp.c:nn=LineNumber


INFORMATION

	- info 		
		address SYM	|| Get address for symbol SYM
		symbol ADDR	|| Show symbol at specified address

		all-registers	|| all registers & their contents
		
		breakpoints
		
		files		|| get Entry point + sections
		files		|| Names of targets & files being debugged

		functions	|| all function names in Program
		functions UefiMain  || show where this function occurs

		line

		types [regex]	|| list all types or with regex

		args		|| Argument variables of current stack frame
		locals		|| local variables of current stack frame
		variables	|| all gloabl & static variables


CONTROL FLOW

	- c			|| continue
	- next			|| move only one step forward
	- bt			|| print back_trace of all stack frames
	- stop			|| stop program until it reaches a different source line

FILES (perhaps not applicable when debugging with QEMU)

	- file MemtestEfi.efi	|| load file   ...no debugging symbols found...done
	- file			|| unload files

LIST

	- list			|| list specified function or line

gdb --tui
	- layout asm
	- layout reg
	- layout src

	- tui enable
	- tui disable

	- next

	- ctrl+x o		|| change active window

	- ctrl+x 1		|| use TUI layout with one window
	- ctrl+x 2		|| use TUI layout with two windows

	- PgUp			|| scroll the active window one page up
	- PgDn			|| scroll the active window one page down

	- Up			|| scroll the active window one line up
	- Down			|| scroll the active window one lin down
	- Right
	- Left

	- C+L			|| refresh the screen

VARIABLES
	info locals
	info variables
	info args

	|| Set is the same as print except that the expression's value is not printed
	|| and is not put in the value history.
	||  if your program has a variable width, you get an error if you try to set
	|| a new value with just ‘set width=13’, because GDB has the command set width
	|| To avoid to set silently general variables to invalid values, ALWAYS use
	|| set var x=4
	print x=4
	set x=4 or set variable x=4
	whatis x -> type = double

DISSASEMBLE BINARIES
	gdb -batch -ex 'file /bin/ls' -ex 'disassemble main'
	Also, -ex 'set disassembly-flavor intel' before other -exs will result in Intel assembly syntax

	gcc -O0 -ggdb3 -std=c99 -Wall -Wextra -pedantic -o main.out main.c
	gdb -batch -ex "disassemble/rs myfunc" main.out