I found the following lines in kernel/proc.c, to regulate the ipc from
userspace into kernel tasks. However, those lines are disabled through
the "#if 0" preprocessor statement.

    #if 0
      if ((iskerneln(src_dst_p) && _function != SENDREC
               && _function != RECEIVE)) {
    #if DEBUG_ENABLE_IPC_WARNINGS
          kprintf("sys_call: trap %d not allowed, caller %d, src_dst %d
\n",
              function, proc_nr(caller_ptr), src_dst);
    #endif
          return(ETRAPDENIED);          /* trap denied by mask or kernel */
      }
    #endif

I am a little irritated about these lines due to two reasons.

1st. why haven't those disabled lines been cropped from the source
code, when
2nd., Jorrit N. Herder rewrote ipc and system call handling in 2005 as
file comments tell, especially as
3rd., these lines seem to be superseded by the introduction of the
"sys_map_t s_ipc_from", "sys_map_t s_ipc_to" and "sys_map_t
s_ipc_sendrec" variables in proc.h

So, can anyone support/refute my assumption, these lines are legacy
and outdated?

Thanks for your ideas,

Alex

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As I'm currently about to port Minix to a research processor platform,
some more questions like this may arise in future...