full-system-instrumentation.md

Full system instrumentation with kcov

Prerequisites

You need to install patchelf >= 0.9 on your system before recording. Patchelf can be found on https://github.com/NixOS/patchelf, or as a package on some distributions (note the version though!).

Add the kcov-system-daemon to your target system

You need to add kcov-system-daemon to your target system and start it early during system bootup. This is needed in order to process instrumentation points and write report data.

Instrumenting binaries for a target system

If your binaries (with debug symbols) are in e.g., sysroot, you can instrument binaries using

kcov-system --system-record /tmp/out-sysroot sysroot

After this finishes, build your filesystem (squashfs etc) using the instrumented binaries and install and run on your target.

Note that --system-record also produces a shared library (libkcov_system_lib) which needs to be available in the library on the target system. kcov places it in /lib under /tmp/out-sysroot.

Creating a report from the collected data

Copy /tmp/kcov-data from your target system and run

kcov-system --system-report /tmp/kcov /tmp/kcov-data