The Oracle Solaris kernel can dynamic load and unload kernel modules. When FBT is loaded and a module is dynamically loaded, FBT automatically provides new probes associated with the new module. If a loaded module has no enabled FBT probes, the module may be unloaded; the corresponding probes will be destroyed as the module is unloaded. If a loaded module has enabled FBT probes, the module is considered busy, and cannot be unloaded.