GDB 10.0 introduced a Python API to allow you to create your own custom Tui Windows in Python.
I’ve created a register Tui Window and register GDB command, that allows you to display a custom list of general, single, double and vector registers. This allows you to focus only on a small set of registers while debugging a piece of assembler. You can toggle individual registers to display in hex, signed, unsigned or float format.
Armv8a: r, s, d and q
AArch64: x, w, s, d, v, b, h, q
It also highlights any changed values since the previous step. The window is also scrollable. The Python program general.py works for both AArch64 and Armv8-a.
register and Enabling the register Custom WindowBest set up is to create a GDB command file.
a1-gdb.gdb auto load GDB command file
# include the Python script
so general.py
# create a new Tui layout including the new custom window register
tui new-layout debug1 register 1 src 2 status 0 cmd 1
# enable the layout
layout debug1
# all general registers plus special ones
reg x0 - x30 pc sp cpsr
# or a small focus selection
reg x0 - x4 d0 - d6 s0 - s3
# display some in hex
reg hex on x5 - x10
$ gdb -q a1
(gdb) help reg
Add registers to the custom TUI Window register.
register OPT|/FMT register-list
/FMT: x: hex, z: zero pad hex, s: signed, u: unsigned, f: float
OPT: del register-list
clear - clear all registers from the window
Ranges can be specified with -:
register x0 x10 - x15 s0 s4 - s6 d5 - d9 w0 x10 - w15
Special registers: lr, pc, sp, cpsr, fpsr, fpcr
You can still change the layout in GDB.
(gdb) layout reg
Then back again to the custom layout
(gdb) layout debug1
The last set of registers from before will be restored.
Gain focus to scroll the window with the up and down cursor keys or mouse scroll button.
(gdb) focus register
Info about current layout
(gdb) info win
Get focus on a particular window
(gdb) focus [name]
Change window heights
(gdb) wh register +4
Display all layouts
(gdb) layout
Enable/disable Tui
(gdb) tui [enable|disable]
You can use the GDB history to easily recover previous ‘register’ commands and switch between different custom register lists. To your .gdbinit file add the following and see the gdb docs for more info.
set history save
If when quitting GDB the command prompt no longer display properly try this to restore it.
$ stty sane
Tui disable messes up GDB. This is because tui.is_valid() is not set to False. I think this might be fixed in a later version of GDB according to the docs. You will probably have to use $ stty sane if you do (gdb) tui disable and then quit GDB.
For better display of vector registers see vector.py
gdb.Value object returned by read_register()
which mean the main code to build up the register view no longer has to worry to much about what kind of register it is.The wiki page was retrospectively converted into a post.