OpenVMS Alpha Galaxy Guide
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  16.1  SYS$CPU_TRANSITION

  On Alpha systems, changes the current processing state
  of a CPU in the configure set of the current system or an
  unassigned CPU in an OpenVMS Galaxy configuration.
  This service completes asynchronously.  For synchronous
  completion, use the $CPU_TRANSITIONW service.

  This service accepts 64-bit addresses.  Parameter and bit
  definitions are resolved in $CSTDEF in the appropriate

  STARLET library.

  Format

  SYS$CPU_TRANSITION tran_code, cpu_id, nodename,
  node_id, flags, efn, iosb, astadr_64, astprm_64

  Arguments

  tran_code

  OpenVMS usage:               longword
  type:                        longword (unsigned)

  access:                      read only
  mechanism:                   by value

  Identifier specifying the type of state change to be initiated
  on the target CPU. The    tran_code    argument is a longword
  containing one of the following values:

  Symbolic Name                Description

  CST$K_CPU_STOP               The target CPU is to be removed from
                               the active set and halted into console
                               mode.  It remains in the configure set
                               of the current partition.

  CST$K_CPU_MIGRATE       The target CPU is removed from the
                               configure set of the local partition and
                               the console is requested to add it to the
                               configure set of the partition specified
                               in node_id.  If the CPU is currently
                               in the active set, it is automatically
                               brought to console mode through the
                               CST$K_CPU_STOP function first.

  CST$K_CPU_START              The target CPU is requested to exit
                               console mode and join the active set of
                               the current partition.  The CPU must
                               already be part of the configure set.
  CST$K_CPU_FAILOVER      The CPU is assigned a default target
                               partition where it will automati-
                               cally migrate on system failure.  This
                               assignment persists until it is super-
                               seded.  To remove an assignment or
                               partition name, the current partition
                               ID should be specified.

  cpu_id

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

  Identifier of the CPU whose state is to be modified.  The  cpu_

  id argument is a longword number in the supported range
  of individual CPUs from 0 to SYI$_MAX_CPUS - 1.  In a
  Galaxy, this CPU must be in the configure set of the local
  partition or not assigned to any other partitions.  The symbolic
  values, CST$K_ANY_LOCAL_CPU can be used in certain
  types of transitions to allow the next available processor of the
  appropriate type be used instead of a specific one.

  node_id

  OpenVMS usage:               longword
  type:                        longword (unsigned)

  access:                      read only
  mechanism:                   by value

  Identifier of the target Galaxy partition in CST$K_CPU_

  ASSIGN, CST$K_CPU_FAILOVER, or CST$K_CPU_
  MIGRATE transition.  The     node_id    argument is a long-
  word containing a number in the supported range of IDs
  provided by the console for the current hardware platform.  If
  the nodename     parameter is specified,  node_id   is ignored.

  flags

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

  Options selected for the CPU state transition.  The  flags  ar-
  gument is a longword bit vector wherein a bit corresponds
  to an option.  Only the bits specified below are used; the
  remainder of the longword bits are reserved and must be

  0.

  Each option (bit) has a symbolic name.  The    flags argument
  is constructed by performing a logical OR operation using the
  symbolic names of the following options:

  Symbolic Name                Description

  CST$V_CPU_DEFAULT_           At the completion of the transition, the
  CAPABILITIES                 CPU's user capabilities are set back to
                               the default system value. If this option
                               is not specified, modified user capa-
                               bilities are maintained across STOP
                               and START transitions as long as the
                               CPU remains in the local partition
                               configure set.

  CST$V_CPU_ALLOW_             The transition is to be allowed even
  ORPHANS                      though it will leave at least one thread
                               in the system unable to execute on any
                               CPU in the active set.

  efn

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

  The event flag to be set when the state transition attempt has
  completed.  The  efn  argument is a longword specifying the
  number of the event flag; however, this service only uses the
  low-order byte.

  When you invoke $CPU_TRANSITION, the specified event
  flag is cleared; when the operation is complete, the event flag
  is set.

  iosb

  OpenVMS usage:               io_status_area
  type:                        IOSB structure
  access:                      write only
  mechanism:                   by 32-bit or 64-bit reference

  The I/O status area to receive the final completion status of
  the transition operation.  The iosb  argument is the 32-bit or

  64-bit virtual address of the I/O status area.  The I/O status
  area structure is 32 bytes in length; its definition can be found
  in $IOSBDEF in STARLET.MLB for macro and in the file
  IOSBDEF.H in SYS$STARLET_C.TLB for C.

  When you call $CPU_TRANSITION, the I/O status area is
  cleared.  After the transition operation is complete, the block is
  modified as follows:

  Symbolic Name                Description

  iosb$w_status                The first word contains the condi-
                               tion value return, indicating the final
                               completion status of the operation.

                               The first bit in the second word of the
                               IOSB is set only if an error occurred
                               during the operation; the remaining
                               bits are zeroes.

  astadr_64

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

  The AST routine to be executed when the requested transition
  attempt has completed.  The astadr_64 argument is the 32-
  bit or 64-bit virtual address of this routine.  If you specify the
  astadr_64 argument, the AST routine executes at the access
  mode from which the state transition was requested.

  astprm_64

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

  The quadword AST parameter to be passed to the AST rou-
  tine.

  Description

  The state transition in tran_id   is requested for the target
  cpu_id  .

  A CPU currently in the active set can transition:

  *   To the STOPPED state; removed from the active set and
      left in the configure set, halted in console mode.

  A CPU in the configure set can transition:

  *   To the ACTIVE state; warm rebooted and a full member
      of the SMP active set on the requesting partition.

  *   To another partition through reassignmnet; the target
      CPU is removed from the configure set and added to the
      configure set of the partition specified bynode_id    .

  CPU state transition is a two-phase operation in the
  OpenVMS scheduling model.  This service initiates the re-
  quest in the process context of the caller and returns the
  setup status in the service condition value.  Phase 2 proceeds
  asynchronously; the   efn and  iosb arguments can be used to
  indicate the completion of the transition through the standard
  wait system services.  Additional notification of the comple-
  tion can be made through the OpenVMS AST mechanisms
  using a routine specified in astadr_64   and a user-supplied
  parameter in   astprm_64   .

  Required Privileges
  The caller must have the CMKRNL privilege to call

  SYS$CPU_TRANSITION to modify CPU states.

  Related Services

  $CPU_TRANSITIONW

  Condition Values Returned

  SS$_NORMAL                   The service completed successfully

  SS$_BADPARAM                 One of more arguments has an invalid
                               value or the specified CPU is not in
                               the configuration

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

  SS$_NOCMKRNL                 Caller does not have CMKRNL privi-
                               lege needed to complete operation

  SS$_INSFARG                  Fewer than the required number
                               of arguments were specified or no
                               operation was specified

  SS$_TOO_MANY_ARGS       More arguments were specified than
                               are allowed by the service

  SS$_INVCOMPID                The target gNode ID is not valid in
                               this configuration

  SS$_CPUNOTACT                The specified CPU is not part of the
                               current partitions's active set

  SS$_NOSUCHCPU                The specified CPU does not exist in the
                               current hardware configuration, or
                               is not in the configure set of the local
                               partition

  SS$_CPUSTARTD                The specified CPU is already in the
                               local active set, or is in the process of
                               joining it

  SS$_CPUSTOPPING              The specified CPU is already
                               STOPPED or in the processing of
                               leaving the active set
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