This repository presents how to easily trace a FreeRTOS system using BareCTF and Trace Compass.
By reusing existing open source projects, FreeRTOS systems can be easily traced with low cost. BareCTF is a project that can generates ANSI C code source for a tracer that produces CTF data streams. Trace Compass supports both CTF data streams and user scripted analyses, allowing us to take advantage of its many views and scalable data structures.
FreeRTOS already comes with tracepoints inserted in the code source as C macros. By default, these macros expands to nothing. BareCTF uses YAML configuration to define the tracer and its events. Once the tracer is generated, we can provide our own macros that replaces the tracepoints.
To generate the tracer, simply execute make at the root of the repository.
In your project, you need to add include/ to your include directories. You
also need to compile and link the files in source/ directory.
Finally, you need to include freertos-trace.h
in your FreeRTOSConfig.h to replace the placeholder tracepoints.
You might need to adjust config.yaml and
freertos-types.yaml to fit your system.
BareCTF only generates the CTF tracer. Since there are many kind of embedded systems (e.g. single core or multiple cores, differents operating systems, different clock source, etc.), it does not provide any kind of ring buffer or other optimised data structures.
The platform is user provided, its job is to supply the clock source, store the events in buffers and send (e.g. UART) or save the buffer into memory (e.g. flash). You can follow the documentation to create your own platform.
Trace Compass has many features, supports many trace format and many analyses.
There are many resources on how to get started with it, here's one.
Javascript analyses are supplied in the scripts/ directory. To install them
in Trace Compass, you can follow this guide.
This analysis uses Trace Compass' state system to generate a control flow view that shows the state of all task in the system.
Maximum stack usage is likely to be reached at context switch since the task context is pushed on the stack. This analysis use the stack size after each task has switched out to estimate the stack usage.
Many tracepoints are not generated for now since they aren't needed in the current analyses. That said, they can be easily added.
This is an example to test srv32 on FreeRTOS. The code can be run on the ISS (Instruction Set Simulator) of srv32 to generate CTF trace data. I use srv32 to run the test, and this can be easily ported to another platform.
Requirement: Install the toolchains. See details in srv32 Building toolchains section.
The file "trace.ctf" will be generated under tracedata folder. Open it by the Trace Compass.
$ make run
Feel free to contact me or open an issue if any help is needed.