> > Fix the return value of logioctl() for unhandled ioctl; return EPASSTHROUGH
> > instead of -1.  Fix suggested by Andrew Brown.
> 
> Is there a reference that you can point me at which describes the
> semantics of EPASSTHROUGH?

Following mail in archive and log message of sys/kern/sys_generic.c
rev. 1.61 or ask Andrew Brown.

http://mail-index.netbsd.org/tech-kern/2002/03/10/0007.html
http://mail-index.netbsd.org/tech-kern/2002/03/13/0000.html

enami.