The contents of the kernel, which were formerly in a single file, /vmunix, are now contained in modules in a platform-independent and platform-dependent directory hierarchy. By default, the directory hierarchy is:
The directory search path for modules can be set by the moddir variable in the /etc/system file. Typically, /kernel/genunix is the first portion of the kernel to be loaded. See system(4) and kernel(1M) for more information.