OpenVMS Alpha Galaxy Guide
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  14.1  $SET_SYSTEM_EVENT

  Set System Event

  Establishes a request for notification when an OpenVMS
  system event occurs.

  Format:

  SYS$SET_SYSTEM_EVENT (event ,astadr ,astprm, acmode,
  flags, handle)

  C Prototype:

  int sys$set_system_event (unsigned int event,  void
  (*astadr)(_ _unknown_params), int astprm, unsigned int
  acmode, unsigned int flags, struct _generic_64    *handle;

  Arguments:

  event

  OpenVMS        event_code
  usage:

  type:          longword (unsigned)
  access:        read only
  mechanism:     by value

  Event code indicating the type of system event for which
  an AST is to be delivered.  The  event  argument is a value
  indicating which type of event is of interest.

  Each event type has a symbolic name.  The $SYSEVTDEF
  macro defines the following symbolic names.

  Symbolic Name                              Description

  SYSEVT$C_ADD_MEMBER                        One or more OpenVMS
                                             instances have joined
                                             the OpenVMS Galaxy
                                             sharing community.
  SYSEVT$C_DEL_MEMBER                        One or more OpenVMS
                                             instances have left
                                             the OpenVMS Galaxy
                                             sharing community.

  SYSEVT$C_ADD_ACTIVE_CPU                    One or more proces-
                                             sors have become active
                                             within this OpenVMS
                                             instance.

  SYSEVT$C_DEL_ ACTIVE_CPU                   One or more processors
                                             have become inactive
                                             within this OpenVMS
                                             instance

  SYSEVT$C_ADD_CONFIG_CPU                    One or more proces-
                                             sors have become active
                                             within this OpenVMS
                                             instance.
  SYSEVT$C_DEL_CONFIG_CPU                    One or more processors
                                             have become inactive
                                             within this OpenVMS
                                             instance.

  astadr

  OpenVMS usage:               ast_procedure
  type:                        procedure value
  access:                      call without stack unwinding
  mechanism:                   by 32-bit or 64-bit reference

  Notification AST routine to receive control after a change in
  OpenVMS system configuration occurs.

  astprm

  OpenVMS usage:               user_arg
  type:                        quadword
  access:                      read only
  mechanism:                   by value

  The quadword AST parameter to be passed to the AST
  routine.

  acmode

  OpenVMS usage:               access_mode
  type:                        longword (unsigned )

  access:                      read only
  mechanism:                   by value

  Access mode at which the system event AST is to execute.
  The  acmode    argument is a longword containing the access
  mode.

  Each access mode has a symbolic name.  The $PSLDEF
  macro defines the following symbols for the four access
  modes.

  Symbolic Name                Description

  PSL$C_KERNEL                 Kernel

  PSL$C_EXEC                   Executive

  PSL$C_SUPER                  Supervisor
  PSL$C_USER                   User

  The value of the access mode is maximized with the access
  mode of the caller.

  flags

  Defined in SYSEVTDEF.

  SYSEVT$M_REPEAT_             When this flag is set, event notification
  NOTIFY                       will be repeated.

  handle

  OpenVMS usage:               handle
  type:                        quadword (unsigned)
  access:                      read/write
  mechanism:                   by reference

  The virtual address of a naturally aligned quadword for the
  event handle.

  Description

  The Set System Event service establishes a request for noti-
  fication when a system event occurs.  It may create a new
  system event notification object, add an event to a (new or
  existing) object, and enable notification on a (new or existing)

  object.

  If the handle   specified is zero, a new system notification
  request object is created, and a handle for the new object is
  returned.

  If theevent   specified is non-zero, that event is added to the
  set of events which trigger notification on the notification
  object.

  The service will verify that the input parameters spec-
  ify a valid request and enable the object for notification.
  Notification is accomplished by AST delivery.  After the AST
  has been delivered, notification must again be enable on the
  object before another notification (AST delivery) can occur if
  flag is not set.

  Errors will be returned in the following cases:

  *   If quotas are exceeded, an error will be returned.  It is
      important to note that this routine will return an er-
      ror and will not retry an attempt to get quota if quota is
      exhausted on the first attempt.

  *   See the Condition Values Returned section for types of
      errors that can be returned.

  *   If theastadr    argument is omitted, and a new notifi-
      cation object is being created, SS$_BADPARAM will be
      returned.

  *   If theevent    argument is incorrectly specified, SS$_

      BADPARAM will be returned.

  *   If the access mode parameter is more privileged than the
      mode of the caller, the mode of the caller will be used.

  *   If specified, thehandle   argument must be writeable
      from the mode of the caller.  SS$_ACCVIO is returned if
      this is not the case.

  Required Privileges

  None.

  Required Quota

  ASTLM.

  Related Services

  $CLEAR_SYSTEM_EVENT

  Condition Values Returned

  SS$_NORMAL                   The service completed successfully.

  SS$_ACCVIO                   The service cannot access the locations
                               specified by one or more arguments.

  SS$_BADPARAM                 One of more arguments has an invalid
                               value.

  SS$_EXASTLM                  The process exceeded its quota for
                               outstanding ASTs.

  SS$_INSFMEM                  The system dynamic memory is insuf-
                               ficient to complete the service.
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