In general iPXE files are licensed under the GPL. For historical reasons, individual files may contain their own licence declarations. Most builds of iPXE do not contain all iPXE code (in particular, most builds will include only one driver), and so the overall licence can vary depending on what target you are building. The resultant applicable licence(s) for any particular build can be determined by using "make bin/xxxxxxx.yyy.licence"; for example: make bin/rtl8139.rom.licence to determine the resultant licence(s) for the build bin/rtl8139.rom