Open flex-builder , find build_distro_rfs_yocto() function it is called by flex-builder -i mkrfs -r command and look :
build_distro_rfs_yocto() function calls flex-builder -c apps -r yocto:$DISTROSCALE -a ${DESTARCH} -f $CONFIGLIST
which will call the Makefile , The Makefile calls (repo.mk) build_dependent_rfs which calls
flex-builder -i mkrfs -r which calls build_distro_rfs_yocto() which calls flex-builder -c apps -r yocto:$DISTROSCALE -a
which will call the Makefile The Makefile calls (repo.mk) build_dependent_rfs which calls
flex-builder -i mkrfs -r which calls build_distro_rfs_yocto() ..........I can continue if you still don't get it
Red calls Red -> infinite recursion
If it is too complicated for you to understand then
Try to include tsntool in yocto:tiny build. It doesn't work because the Makefile has that line (below) for tsntool
Replace the word tiny with any word like tinyYW for instance . Now, flex-builder will build tsntooll for yocto:tiny and will go in the infinite LOOP
@[ $(DISTROTYPE) != ubuntu -a $(DISTROTYPE) != yocto -o $(DISTROSCALE) = mate -o $(DISTROSCALE) = tiny ] && exit ||
