I've managed to get various architectures tested in qemu-emulation in this PR: https://github.com/boostorg/config/pull/366, with help from https://github.com/uraimo/run-on-arch-action However, for armv7 alone I see: /home/runner/work/config/boost-root/tools/build/src/build/type.jam:158: in type.validate from module type error: Unknown target type EXE (builtin):-1: in sequence.transform from module sequence /home/runner/work/config/boost-root/tools/build/src/build/generators.jam:239: in generator.__init__ from module object(installed-exe-generator)@4 /home/runner/work/config/boost-root/tools/build/src/tools/stage.jam:568: in class@installed-exe-generator.__init__ from module object(installed-exe-generator)@4 /home/runner/work/config/boost-root/tools/build/src/kernel/class.jam:90: in new from module class /home/runner/work/config/boost-root/tools/build/src/tools/stage.jam:596: in load from module stage /home/runner/work/config/boost-root/tools/build/src/kernel/modules.jam:295: in import from module modules /home/runner/work/config/boost-root/tools/build/src/tools/builtin.jam:27: in load from module builtin /home/runner/work/config/boost-root/tools/build/src/kernel/modules.jam:295: in import from module modules /home/runner/work/config/boost-root/tools/build/src/build-system.jam:12: in load from module build-system /home/runner/work/config/boost-root/tools/build/src/kernel/modules.jam:295: in import from module modules /home/runner/work/config/boost-root/tools/build/src/kernel/bootstrap.jam:139: in boost-build from module /home/runner/work/config/boost-root/boost-build.jam:17: in module scope from module This is while running ./b2 headers. The initialization/setup code is the same for each architecture as they're run in a GHA matrix so I don't think I've goofed in the CI script. Anyone any ideas what might cause this? Many thanks, John. -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus