When the Stubs.c component of a module's Driver Software Package (DSP) is installed, idinstall(1M) stores the module's Stubs.c file information in /etc/conf/pack.d/module-name/stubs.c where module-name is the name of the module being installed. Package scripts should never access stubs.c files directly; only the idinstall command should be used.
A module's Stubs.c file contains function name and variable definition stubs for symbols defined in the module that can be referenced by other kernel modules being configured into the system. At compile time, the definitions in the Stubs.c file give the kernel the ability to resolve references made to the absent module's symbols.