Debugging on Host ==================== Required tools and hardware --------------------------- A GNU C/C++ debugger is the only requirement for the Host architecture. Make sure that you have the following executable in your PATH:: gdb No additional hardware is required. Recompilation is required ------------------------- In order to debug applications based on Sming Framework make sure that you are using Sming version 3.8.0 or newer. Compilation directives ~~~~~~~~~~~~~~~~~~~~~~ If you want to debug your application and the Sming Framework code make sure to (re)compile it with :envvar:`ENABLE_GDB` =1 directive:: cd $SMING_HOME/../samples/LiveDebug make dist-clean make ENABLE_GDB=1 The commands above will re-compile Sming with debug symbols and optimizations for debugging. These commands need to be executed once. You can recompile Sming with the following directives to debug better Sming and the LWIP TCP/IP stack :: cd $SMING_HOME/../samples/LiveDebug make Sming-build all ENABLE_GDB=1 ENABLE_LWIPDEBUG=1 Application ~~~~~~~~~~~ To use, (re)compile your application with the ENABLE_GDB option and flash it to the board. For this example we will use the :sample:`LiveDebug` sample application:: cd $SMING_HOME/../samples/LiveDebug make clean make ENABLE_GDB=1 # -- recompiles your application with debugging support The next step is to start the debugger. This can be done with the command below:: make gdb After that a new interactive debugging session will be started:: Welcome to SMING! Type 'r' to run application To start the execution of the application type `r` or `run`:: (gdb) r Starting program: /x/Sming/samples/LiveDebug/out/Host/debug/firmware/app --flashfile=out/Host/debug/firmware/flash.bin --flashsize=4M --pause [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1". [New Thread 0xf7bdcb40 (LWP 16428)] Welcome to the Sming Host emulator host_flashmem_init: Created blank "out/Host/debug/firmware/flash.bin", 4194304 bytes ... main: >> Starting Sming << You can pause the program execution by pressing `Ctrl-C`. And work further using some further GDB commands. The next paragraph describes some of them. GDB commands ------------ There are multiple commands supported in GDB and we will mention only some of them. List current source code ~~~~~~~~~~~~~~~~~~~~~~~~ One possibility is to see the source code of the current line where the execution has stopped. To achieve this you should type ``list`` in the gdb console:: (gdb) list 102 } 103 } 104 105 int main(int argc, char* argv[]) 106 { 107 trap_exceptions(); 108 109 host_printf("\nWelcome to the Sming Host emulator\n\n"); 110 111 static struct { Break the execution ~~~~~~~~~~~~~~~~~~~ This command will pause the debugger once it reaches a specific function or line in the code. This is called ``breakpoint`` and can be set like this:: (gdb) break blink Breakpoint 1 at 0x40105d4c: file app/application.cpp, line 66. Continue the execution ~~~~~~~~~~~~~~~~~~~~~~ To continue the execution of the application we can use the ``continue`` command:: (gdb) continue Continuing. Breakpoint 1, blink () at app/application.cpp:66 66 { (gdb) Because we have set already a breakpoint for the ``blink`` function the execution will be paused when the ``blink`` function is reached and from here you can go to the next line or see the current values of the variables. Go to the next line ~~~~~~~~~~~~~~~~~~~ This can be done using ``next``:: (gdb) next 67 digitalWrite(LED_PIN, ledState); See variable value ~~~~~~~~~~~~~~~~~~ The command to see a value is ``print`` followed by the name of the value. For example to see the value of the ``ledState`` variable inside the ``blink`` function we could type:: (gdb) print ledState $1 = true You can see more useful commands :ref:`here `. Or watch the following short video .. image:: https://img.youtube.com/vi/hVwSX_7Ey8c/3.jpg :target: https://www.youtube.com/watch?v=hVwSX_7Ey8c Debugging with visual debuggers like Eclipse CDT ------------------------------------------------ A good visualization helps us understand things faster. What we can do is use `Eclipse CDT `__ and its debugging plugins to do remote debugging as we did from the command line. Here is how this can be done: - Start Eclipse CDT and import the :sample:`LiveDebug` sample: - Select *File* -> *New* -> *Project* -> *C/C++* -> *Makefile Project with Existing Code* - Point Eclipse to the location of the LiveDebug sample - Import the Sming Framework (if you haven’t done it yet) .. figure:: debugging-1.png :alt: Import Project Import Project Once the two projects are in Eclipse, set the *LiveDebug* project to reference the *Sming* project. Now create a new *Debugging* Configuration: - Select *Run* -> *Debug Configurations* -> *C/C++ Application* - Right-click and create a new *C/C++ Application* - In the *Main* tab set, set: - *Project*: *Basic_Build* - *C/C++ Application*: *out/Host/debug/firmware/app* - disable for now the *auto* build .. figure:: debugging-2.png :alt: C/C++ Application C/C++ Application Then go to the Debugger tab and point the GDB debugger to your gdb binary. (Type ``make list-config`` and look for :envvar:`GDB`.) .. figure:: debugging-3.png :alt: Debugger configuration Debugger configuration We are now ready for debugging. Press the *Debug* button. (In the screenshot above the Debug button is in the bottom-right corner.) After some seconds your debugging session should be up and running and you can enjoy live debugging. .. figure:: eclipse.png :alt: Live Debugging Session Live Debugging Session You will be able to see the current variables and their values. You should be able to go step by step, go inside of functions, add add breakpoints and watchpoints.