kernel functions - dtrace output

Not sure if this has been asked before or not, or if this is the right forum, but the search didn't find anything.  So, looking at the following output from a dtrace script (mentioned in the Dtrace book) I can see that things are listed as kernel_module--function...is there anyway of locating a description of what those functions do?  For example, genunix`sotpi_recvmsg+0x2ac, I can see that genunix is the kernel module and sotpi_recvmsg is the function, so is there a way to find out what genunix does (modinfo doesn't really indicate what genunix does) or is for and what the sotpi_recvmsg function does?