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C Support

The Polar Signals Agent can profile any C binary by default and doesn't need any special compilation flags for collection.

It uses the .eh_frame section in ELF binaries to perform unwinding of stacks.

Symbolization​

For memory addresses to be translated to human readable function names, file names, and line numbers, Polar Signals Cloud must be provided with what is referred to as "debuginfos". Debuginfos can be part of the production binary, or can be uploaded separately in CI/CD pipelines.

tip

We recommend having debuginfos available in production binaries. Everything will just work out of the box without having to upload the debuginfo separately in CI/CD pipelines, and it's always a good idea to have your binaries be debuggable for when the time comes.

To generate debuginfos use the -g flag.

For example with clang:

clang main.c -o main -g

Or with gcc:

gcc main.c -o main -g

If you want to not ship debuginfos in your production binaries you can now extract them from the binary, either with objcopy or strip.

With objcopy:

objcopy --only-keep-debug main main.debug # creates the main.debug file containing debuginfos
objcopy --strip-debug main # removes the debuginfo sections from the binary

Or with strip:

strip --only-keep-debug main.debug # creates the main.debug file containing debuginfos
strip --strip-debug --strip-unneeded # removes the debuginfo sections from the binary

The main.debug could now be uploaded separately in a CI/CD pipeline to Polar Signals Cloud. If debuginfos are available in the production binary this step is not necessary.