278 lines
11 KiB
ReStructuredText
278 lines
11 KiB
ReStructuredText
.. include:: /substitutions.rst
|
|
.. _debugging:
|
|
|
|
=========
|
|
Debugging
|
|
=========
|
|
|
|
Finding and fixing bugs is an important part of the hardware and software development process. Sometimes you also need
|
|
to use debugging techniques to understand how the system works. Two tools that are helpful are debug logging and
|
|
debugging using the GNU Debugger (gdb).
|
|
|
|
Debug Logging
|
|
=============
|
|
|
|
NuttX has a powerful system logging facility (syslog) with ``info``, ``warn``, and ``error`` levels. You can enable
|
|
debugging for your build for the subsystem or feature by using the ``menuconfig`` system.
|
|
|
|
The debug options are available under :menuselection:`Build Setup --> Debug Options`. You will most likely have to enable the
|
|
following options:
|
|
|
|
* :menuselection:`Enable Debug Features` — selecting this will turn on subsystem-level debugging options, they will become visible
|
|
on the page below. You can then select the ones you want.
|
|
* :menuselection:`Enable Error Output` — this will only log errors.
|
|
* :menuselection:`Enable Warnings Output` — this will log warnings and errors.
|
|
* :menuselection:`Enable Informational Debug Output` — this will produce informational output, warnings, and errors.
|
|
|
|
You can then select from the subsystems that are available, Network, Scheduler, USB, etc. Note that you will need to
|
|
separately enable the subsystem elsewhere in the ``menuconfig`` system. To see the ``CONFIG`` define that is set,
|
|
use the arrow keys to highlight the subsystem (for instance, :menuselection:`Network Debug Features`) and type :kbd:`?`. This will show
|
|
you that the C macro that is set is called ``CONFIG_DEBUG_NET``. ``debug.h`` defines the ``netinfo()`` logging
|
|
function that will log output if this macro is set. You can search the source code for ``netinfo`` to see how it is
|
|
used.
|
|
|
|
.. image:: ../_static/images/menuconfig-debug.png
|
|
:width: 800px
|
|
:align: center
|
|
:alt: Screenshot of menuconfig system main screen
|
|
|
|
Note that enabling all these will produce an incredible amount of logging output. Enable the level you want and
|
|
the area you're interested in, and leave the rest disabled, save the config, and then recompile. You can see the full
|
|
list of debug feature logging functions in the file
|
|
`debug.h <https://github.com/apache/nuttx/blob/master/include/debug.h>`__.
|
|
|
|
Syslog timestamps can be enabled in the configuration in :menuselection:`Device Drivers --> System Logging --> Prepend
|
|
timestamp to syslog message` (``CONFIG_SYSLOG_TIMESTAMP``).
|
|
|
|
You may need to do a little bit of experimenting to find the combination of logging settings that work for the problem
|
|
you're trying to solve. See the file `debug.h <https://github.com/apache/nuttx/blob/master/include/debug.h>`_
|
|
for available debug settings that are available.
|
|
|
|
There are also subsystems that enable USB trace debugging, and you can log to memory too, if you need the logging to be
|
|
faster than what the console can output.
|
|
|
|
Debugging with ``openocd`` and ``gdb``
|
|
======================================
|
|
|
|
To debug our Nucleo board using its embedded SWD debug adapter,
|
|
start ``openocd`` with the following command:
|
|
|
|
.. code-block:: console
|
|
|
|
$ openocd -f interface/stlink-v2.cfg -f target/stm32f1x.cfg
|
|
|
|
This will start a ``gdb`` server. Then, start ``gdb`` with:
|
|
|
|
.. code-block:: console
|
|
|
|
$ cd nuttx/
|
|
$ gdb-multiarch nuttx/nuttx
|
|
|
|
Inside ``gdb`` console, connect to the ``gdb`` server with:
|
|
|
|
.. code-block::
|
|
|
|
(gdb) target extended-remote :3333
|
|
|
|
You can now use standard ``gdb`` commands. For example, to
|
|
reset the board:
|
|
|
|
.. code-block::
|
|
|
|
(gdb) mon reset
|
|
|
|
To halt the board:
|
|
|
|
.. code-block::
|
|
|
|
(gdb) mon halt
|
|
|
|
To set a breakpoint:
|
|
|
|
.. code-block::
|
|
|
|
(gdb) breakpoint nsh_main
|
|
|
|
and to finally start nuttx:
|
|
|
|
.. code-block::
|
|
|
|
(gdb) continue
|
|
Continuing.
|
|
|
|
Breakpoint 1, nsh_main (argc=1, argv=0x200ddfac) at nsh_main.c:208
|
|
208 sched_getparam(0, ¶m);
|
|
(gdb) continue
|
|
Continuing.
|
|
|
|
.. tip::
|
|
|
|
You can abbreviate ``gdb`` commands: ``info b`` is a shortcut for
|
|
``information breakpoints``; ``c`` works the same as ``continue``, etc.
|
|
|
|
NuttX aware debugging
|
|
---------------------
|
|
|
|
Since NuttX is actually an RTOS, it is useful to have ``gdb`` be aware of the different
|
|
tasks/threads that are running. There are two ways to do this: via ``openocd``
|
|
itself or via ``gdb``. Note that in both cases, you need to enable debug symbols
|
|
(``CONFIG_DEBUG_SYMBOLS``).
|
|
|
|
With openocd
|
|
~~~~~~~~~~~~
|
|
|
|
``openocd`` supports various RTOS directly, including NuttX. It works by reading
|
|
into internal NuttX symbols which define the active tasks and their properties.
|
|
As a result, the ``gdb`` server will directly be aware of each task as a different
|
|
`thread`. The downside of this approach is that it depends on how you build NuttX
|
|
as there are some options hardcoded into
|
|
opencd. By default, it assumes:
|
|
|
|
* ``CONFIG_DISABLE_MQUEUE=y``
|
|
* ``CONFIG_LEGACY_PAGING=n``
|
|
|
|
If you need these options to be set differently, you will have to edit ``./src/rtos/nuttx_header.h`` from ``openocd``,
|
|
change the corresponding settings and then rebuild it.
|
|
|
|
Finally, to enable NuttX integration, you need to supply an additional ``openocd`` argument:
|
|
|
|
.. code-block:: console
|
|
|
|
$ openocd -f interface/stlink-v2.cfg -f target/stm32f1x.cfg -c '$_TARGETNAME configure -rtos nuttx'
|
|
|
|
Since ``openocd`` also needs to know the memory layout of certain datastructures, you need to have ``gdb``
|
|
run the following commands once the ``nuttx`` binary is loaded:
|
|
|
|
.. code-block::
|
|
|
|
eval "monitor nuttx.pid_offset %d", &((struct tcb_s *)(0))->pid
|
|
eval "monitor nuttx.xcpreg_offset %d", &((struct tcb_s *)(0))->xcp.regs
|
|
eval "monitor nuttx.state_offset %d", &((struct tcb_s *)(0))->task_state
|
|
eval "monitor nuttx.name_offset %d", &((struct tcb_s *)(0))->name
|
|
eval "monitor nuttx.name_size %d", sizeof(((struct tcb_s *)(0))->name)
|
|
|
|
One way to do this is to define a gdb `hook` function that will be called when running ``file`` command:
|
|
|
|
.. code-block::
|
|
|
|
define hookpost-file
|
|
eval "monitor nuttx.pid_offset %d", &((struct tcb_s *)(0))->pid
|
|
eval "monitor nuttx.xcpreg_offset %d", &((struct tcb_s *)(0))->xcp.regs
|
|
eval "monitor nuttx.state_offset %d", &((struct tcb_s *)(0))->task_state
|
|
eval "monitor nuttx.name_offset %d", &((struct tcb_s *)(0))->name
|
|
eval "monitor nuttx.name_size %d", sizeof(((struct tcb_s *)(0))->name)
|
|
end
|
|
|
|
You will see that ``openocd`` has received the memory offsets in its output:
|
|
|
|
.. code-block::
|
|
|
|
Open On-Chip Debugger 0.10.0+dev-01514-ga8edbd020-dirty (2020-11-20-14:23)
|
|
Licensed under GNU GPL v2
|
|
For bug reports, read
|
|
http://openocd.org/doc/doxygen/bugs.html
|
|
Info : auto-selecting first available session transport "swd". To override use 'transport select <transport>'.
|
|
Info : target type name = cortex_m
|
|
Info : Listening on port 6666 for tcl connections
|
|
Info : Listening on port 4444 for telnet connections
|
|
15:41:23: Debugging starts
|
|
Info : CMSIS-DAP: SWD Supported
|
|
Info : CMSIS-DAP: FW Version = 1.10
|
|
Info : CMSIS-DAP: Interface Initialised (SWD)
|
|
Info : SWCLK/TCK = 1 SWDIO/TMS = 1 TDI = 0 TDO = 0 nTRST = 0 nRESET = 1
|
|
Info : CMSIS-DAP: Interface ready
|
|
Info : clock speed 1000 kHz
|
|
Info : SWD DPIDR 0x2ba01477
|
|
Info : nrf52.cpu: hardware has 6 breakpoints, 4 watchpoints
|
|
Info : starting gdb server for nrf52.cpu on 3333
|
|
Info : Listening on port 3333 for gdb connections
|
|
Info : accepting 'gdb' connection on tcp/3333
|
|
Error: No symbols for NuttX
|
|
Info : nRF52832-QFAA(build code: B0) 512kB Flash, 64kB RAM
|
|
undefined debug reason 8 - target needs reset
|
|
Warn : Prefer GDB command "target extended-remote 3333" instead of "target remote 3333"
|
|
Info : pid_offset: 12
|
|
Info : xcpreg_offset: 132
|
|
Info : state_offset: 26
|
|
Info : name_offset: 208
|
|
Info : name_size: 32
|
|
target halted due to debug-request, current mode: Thread
|
|
xPSR: 0x01000000 pc: 0x000000dc msp: 0x20000cf0
|
|
target halted due to debug-request, current mode: Thread xPSR: 0x01000000 pc: 0x000000dc msp: 0x20000cf0
|
|
|
|
.. note:: You will probably see the ``Error: No symbols for NuttX`` error appear once at startup. This is OK
|
|
unless you see it every time you step the debugger. In this case, it would mean you did not enable debug symbols.
|
|
|
|
Now, You can now inspect threads:
|
|
|
|
.. code-block::
|
|
|
|
(gdb) info threads
|
|
Id Target Id Frame
|
|
* 1 Remote target nx_start_application () at init/nx_bringup.c:261
|
|
(gdb) info registers
|
|
r0 0x0 0
|
|
r1 0x2f 47
|
|
r2 0x0 0
|
|
r3 0x0 0
|
|
r4 0x0 0
|
|
r5 0x0 0
|
|
r6 0x0 0
|
|
r7 0x20000ca0 536874144
|
|
r8 0x0 0
|
|
r9 0x0 0
|
|
r10 0x0 0
|
|
r11 0x0 0
|
|
r12 0x9 9
|
|
sp 0x20000c98 0x20000c98
|
|
lr 0x19c5 6597
|
|
pc 0x1996 0x1996 <nx_start_application+10>
|
|
xPSR 0x41000000 1090519040
|
|
fpscr 0x0 0
|
|
msp 0x20000c98 0x20000c98
|
|
psp 0x0 0x0 <_vectors>
|
|
primask 0x0 0
|
|
basepri 0xe0 -32
|
|
faultmask 0x0 0
|
|
control 0x0 0
|
|
|
|
With gdb
|
|
~~~~~~~~
|
|
|
|
You can also do NuttX aware debugging using ``gdb`` scripting support.
|
|
The benefit is that it works also for the sim build where ``openocd`` is
|
|
not applicable. For this to work, you will need to enable PROC filesystem support
|
|
which will expose required task information (``CONFIG_FS_PROCFS=y``).
|
|
|
|
To use this approach, you can load the ``nuttx/tools/gdb/__init__.py`` file. An
|
|
easy way to do this is to add an extra command:
|
|
|
|
.. code-block:: console
|
|
|
|
$ gdb nuttx -ix=tools/gdb/__init__.py
|
|
|
|
gdb can need to set the current elf support architecture, for example,
|
|
the prefix is arm-ebai-none-.
|
|
|
|
.. code-block::
|
|
|
|
(gdb) info threads
|
|
Id Thread Info Frame
|
|
*0 Thread 0x20000398 (Name: Idle Task, State: Running, Priority: 0, Stack: 1000) 0x80001ac __start() at chip/stm32_start.c:111
|
|
1 Thread 0x10000188 (Name: nsh_main, State: Waiting,Semaphore, Priority: 100, Stack: 2000) 0x800aa06 sys_call2() at /home/ajh/work/vela_all/nuttx/include/arch/syscall.h:187
|
|
|
|
.. code-block::
|
|
|
|
(gdb) (gdb) nxgcore -r 0x40200000,0x48000000,0x07
|
|
Saved corefile nuttx.core
|
|
Please run gdbserver.py to parse nuttx.core
|
|
|
|
|
|
The python script has extended many commands like ``thread <id>`` ,
|
|
``thread apply <all|id list> cmd``, ``nxsetargs`` etc.
|
|
You can use ``help <command>`` to get help.
|
|
|
|
Note that if you need to continue debugging after using the thread command,
|
|
please use ``c`` instead of ``continue``, because thread will force the register to be set,
|
|
and the `c` command will restore the register before conitune.
|