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KERNELD(8)                     Linux Extensions                     KERNELD(8)

       kerneld  - perform kernel action in user space (such as on-demand load-
       ing of modules)

       kerneld is obsolete as of Linux kernel 2.1.90, it was replaced  by  the
       kmod  kernel  thread and cron entries.  Do not even think of using ker-
       neld unless you are running a 2.0 kernel.

       kerneld [ debug ] [ keep ] [ delay=<seconds> ] [ type=<message  number>

       Apart from automatically removing unused modules, kerneld also performs
       specific kernel tasks in user space by responding to requests from  the
       kernel  via a dedicated IPC message queue.  Access to this queue can be
       made from user space by opening the queue with:

            qid = msgget(IPC_PRIVATE, 0600 | IPC_KERNELD);

       A specific task is requested with the message  type,  as  specified  in

       The structure of a kerneld message is:
            struct kerneld_msg {
                 long mtype;
                 long id;
                 char text[1];
       where  the  id field is used as the number of the response message from
       kerneld back to the kernel.  If the id field is zero, there will be  no
       response from kerneld.
       (Note that a new structure is proposed that will include the pid of the
       requestor into the protocol header.)

       If a response was requested, the exit status of the kerneld action will
       be stored in the id field.

       The  text  field  us used to hold the parameters from the kernel to the
       specified kerneld action.  In return messages, this field  can  contain
       the output from the action, to be used (if wanted) by the kernel.

       The options are as follows:

       debug   Whith  debugging  enabled,  you will be able to see the current
               status of kerneld as it performs its tasks.  Note that you  can
               control  debugging, as well as all the other parameters via the
               utility kdstat.

       keep    The keep option makes kerneld ignore all requests for unloading
               modules.   This  option  might  be usable for systems where the
               modules should never be unloaded at all  (for  some  reason  or
               other).   This  option  also  inhibits the automatic removal of
               unused modules that kerneld performs every minute  (or  <delay>

               The delay option will change the timeout in kerneld for delayed
               removal of modules from the default 60 seconds to whatever  the
               choice was.

       type=<message type>
               The  default type is -255, which means that kerneld will listen
               for all messages where the type is less than or equal  to  255.
               If  a  positive  number  is given, kerneld will only listen for
               that message type.

       kerneld sends error messages to the syslog facility LOG_DAEMON.

       insmod(8), rmmod(8), modprobe(8), depmod(8), syslogd(8)

       The kerneld support was inspired by discussions  with  Jacques  Gelinas

Linux                            May 14, 1995                       KERNELD(8)