NAME

     svrctl - special server control functions


SYNOPSIS

     #include <sys/svrctl.h>

     int svrctl(u32_t request, void *data);


DESCRIPTION

     Svrctl allows root to control the kernel in various ways, or
     implements  some  very  MINIX  3  specific system calls that
     don't deserve their own system call number.

     This system call makes it easy to add new  ways  of  setting
     and  getting  kernel parameters, but at the same time, back-
     wards   compatibility   is   not   guaranteed.    Read   the
     <sys/svrctl.h>  include  file  to see what the struct's men-
     tioned below look like.  Most calls  are  root-only,  unless
     specified otherwise.

     The only way to know how to properly use these calls  is  to
     study  the associated kernel or server code, or the programs
     that already use these calls.

     Current requests are:

     MMSIGNON
          Inform MM that the current process wants  to  become  a
          server.

     MMSWAPON
          Instruct MM to mount a file or device as swapspace.

     MMSWAPOFF
          Tell MM to stop using swapspace.

     FSSIGNON
          Register a new device with FS.

     SYSSIGNON
          Inform the kernel that the process  want  to  become  a
          server.   The  processes  task number is filled-in in a
          struct systaskinfo.

     SYSGETENV
          Request the value of one or all boot  parameters.   Can
          be used by non-root.


RETURN VALUES

     Svrctl returns 0 upon success and -1 upon failure.



AUTHOR

     Philip Homburg <philip@cs.vu.nl>