LTTng Tools is provided under: SPDX-License-Identifier: GPL-2.0-only Being under the terms of the GNU General Public License version 2 only, according with: LICENSES/GPL-2.0 The library part is provided under: SPDX-License-Identifier: LGPL-2.1-only Being under the terms of the GNU Lesser General Public License version 2.1 only, according with: LICENSES/LGPL-2.1 This applies to: include/lttng/* src/lib/lttng-ctl/* In addition, other licenses may also apply, see SPDX-License-Identifier in individual files. LGPL-compatible source code can statically use the library header using: #define _LGPL_SOURCE #include Dynamic-only linking with the LGPL library is used if _LGPL_SOURCE is not defined. It permits relinking with newer versions of the library, which is required by the LGPL license.