We can confirm what build flags are enabled at build time by checking the below places. Default build flags in the source code’s Makefile or build tool’s declaration files (CMakeLists.txt). In the debian/rules file. The build system at build time (dh). As deb packages on different Ubuntu releases have different versions, it is necessary to verify the build flags in deb package and upstream package within the same version. For example, below are the process to verify the build flags of ceph package in Ubuntu 22.