FreeRTOS-Kernel/FreeRTOS/Demo/Posix_GCC

Running with VSCode

Prerequisites

• Install C/C++ extension in VSCode.
• For MacOS or Linux:
  • Install gcc.
  • Install GNU make utility.
  • Install lldb.
• For Windows with Ubuntu WSL:
  • Install WSL.
  • Install Remote Development Extension Pack.
• For Windows with MSYS2:
  • Install MSYS2.
  • Install gcc with pacman -S gcc.
• For all platforms, ensure the required binaries are in PATH with gcc --version, make --version, and either lldb --version or gdb --version.

On MacOS or Linux

1. Open VSCode to the folder FreeRTOS/Demo/Posix_GCC.
2. On the VSCode left side panel, select “Run and Debug”. Then select the “Launch lldb” and press the play button to begin debugging.

On Windows using Ubuntu WSL

1. Navigate to FreeRTOS/Demo/Posix_GCC in Ubuntu WSL and use code . to open the folder in VSCode.
   1. If code is not a recognized command, open VSCode and press CTRL+SHIFT+P. Search for "Shell Command: Install ‘code’ command in Path".
2. On the VSCode left side panel, select the “Run and Debug” button. Then select the “Launch GDB Ubuntu WSL” and press the play button. This will build, run, and attach a debugger to the demo program.
   1. If the demo was previously built by MSYS2, make sure to make clean before building on Ubuntu WSL.

On Windows using MSYS2

2. Open VSCode to the folder FreeRTOS/Demo/Posix_GCC.
3. In .vscode/settings.json, ensure the path variable under MSYS2 is set to the bash.exe under your msys64 installation directory. The path should resemble ${path to msys2 installation}\\msys64\\usr\\bin\\bash.exe.
4. On the VSCode left side panel, select the “Run and Debug” button. Then select the “Launch GDB MSYS2” and press the play button to begin debugging.
   1. If the demo was previously built by Ubuntu WSL, make sure to make clean before building on MSYS2.

Profiling your application

Introduction (from the official gprof doc)

Profiling allows you to learn where your program spent its time and which functions called which other functions while it was executing. This information can show you which pieces of your program are slower than you expected, and might be candidates for rewriting to make your program execute faster. It can also tell you which functions are being called more or less often than you expected. This may help you spot bugs that had otherwise been unnoticed.

Requirements

gprof

Version as tested: GNU gprof (GNU Binutils) 2.36

make

Version as tested: GNU Make 3.82

gcc

Version as tested: gcc (GCC) 11.0.0

Generating Profiles

$ make PROFILE=1

Run your application

$ ./build/posix_demo

Since FreeRTOS and its application never come to an end and typically run forever. The user has to kill the application with Ctrl_C when they feel satisfied that the application achieved its intented task. Killing the application will force the profiling file gmon.out to be generated automatically. In order to make sense of this file, the user has to convert the file with:

$ make profile

After running the previous command, two (2) profiling files prof_call_graph.txt and prof_flat.txt will be generated and placed in the build directory.

• prof_call_graph.txt: The call graph shows which functions called which others, and how much time each function used when its subroutine calls are included.
• prof_flat.txt: The flat profile shows how much time was spent executing directly in each function. In order to understand the outputs generated, the best way is to read the official documentation of gprof here

Run your application with Sanitizers

Introduction

• AddressSanitizer, a fast memory error detector. Memory access instructions are instrumented to detect out-of-bounds and use-after-free bugs
• LeakSanitizer, a memory leak detector. This option only matters for linking of executables and the executable is linked against a library that overrides malloc and other allocator functions

Requirements

gcc

Version as tested: gcc (GCC) 11.0.0

Building and Running the Application

$ make SANITIZE_ADDRESS=1
or
$ make SANITIZE_LEAK=1

Then run your program normally.

$ ./build/posix_demo

If an error is detected by the sanitizer, a report showing the error will be printed to stdout.