VMS Help System Services, $CPU CAPABILITIES (Alpha Only)  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    On Alpha systems, allows modification of the user capability
    set for a specified CPU, or for the global user capability CPU
    default.

    This service accepts 64-bit addresses.

    Format

      SYS$CPU_CAPABILITIES  cpu_id [,select_mask] [,modify_mask]

                            [,prev_mask] [,flags]

    C Prototype

      int sys$cpu_capabilities  (int cpu_id, struct _generic_64

                                *select_mask, struct _generic_64

                                *modify_mask, struct _generic_64

                                *prev_mask, struct _generic_64

                                *flags);

1 - Arguments

 cpu_id

    OpenVMS usage:longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Identifier of the CPU whose user capability mask is to be
    modified or returned. The cpu_id argument is a longword
    containing this number, which is in the supported range of
    individual CPUs from 0 to SYI$_MAX_CPUS -1.

    Specifying the constant CAP$K_ALL_ACTIVE_CPUS applies the current
    modification operation to all CPUs currently in the active set,
    and to the default CPU initialization context in SCH$GL_DEFAULT_
    CPU_CAP. If the prev_mask argument is also supplied, the previous
    default CPU initialization context in SCH$GL_DEFAULT_CPU_CAP will
    be returned rather than any specific CPU state.

    To modify only the user capabilities in SCH$GL_DEFAULT_CPU_CAP,
    the flags argument has a bit constant CAP$M_FLAG_DEFAULT_ONLY.
    When this bit is set, all service operations are performed on
    the global cell rather than on an individual CPU specified in
    the cpu_id argument. This bit does not supersede the CAP$K_
    ALL_ACTIVE_CPUS constant, however. If both constants are
    specified, CAP$K_ALL_ACTIVE_CPUS take precedence; nevertheless,
    the operations to SCH$GL_DEFAULT_CPU are identical because that
    function is a direct subset of the other.

 select_mask

    OpenVMS usage:mask_quadword
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference
    Mask specifying which bits of the specified CPU's user capability
    mask are to be modified. The select_mask argument is the 32-
    or 64-bit address of a quadword bit vector wherein a bit, when
    set, specifies that the corresponding user capability is to be
    modified.

    The individual user capability bits in select_mask can be
    referenced by their symbolic constant names, CAP$M_USER1 through
    CAP$M_USER16. These constants (not zero-relative) specify the
    position in the mask quadword that corresponds to the bit
    name. Multiple capabilities can be selected by connecting the
    appropriate bits with a logical OR operation.

    The constant CAP$K_ALL_USER, when specified in the select_mask
    argument, selects all user capability bits.

 modify_mask

    OpenVMS usage:mask_quadword
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference
    Mask specifying the settings for those capabilities selected in
    the select_mask argument. The modify_mask argument is the 32-
    or 64-bit address of a quadword bit vector wherein a bit, when
    set, specifies that the corresponding user capability is to be
    added to the specified CPU; when clear, the corresponding user
    capability is to be removed from the specified CPU.

    The bit constants CAP$M_USER1 through CAP$M_USER16 can be used
    to modify the appropriate bit position in modify_mask. Multiple
    capabilities can be modified by connecting the appropriate bits
    with OR.

    To add a specific user capability to the specified CPU, that
    bit position must be set in both select_mask and modify_mask. To
    remove a specific user capability from the specified CPU, that
    bit position must be set in select_mask and cleared in modify_
    mask.

    The symbolic constant CAP$K_ALL_USER_ADD, when specified in
    modify_mask, indicates that all capabilities specified in select_
    mask are to be added to the current user capability set. The
    constant CAP$K_ALL_USER_REMOVE indicates that all capabilities
    specified are to be cleared from the set.

 prev_mask

    OpenVMS usage:mask_quadword
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by 32- or 64-bit reference
    Previous user capability mask for the specified CPU before
    execution of this call to $CPU_CAPABILITIES. The prev_mask
    argument is the 32- or 64-bit address of a quadword into which
    $CPU_CAPABILITIES writes a quadword bit mask specifying the
    previous user capabilities.

    If this argument is specified in conjunction with CAP$K_ALL_
    ACTIVE_CPUS as the cpu_id selection constant or with CAP$M_
    FLAG_DEFAULT_ONLY, the user capability portion of the default
    boot initialization state context SCH$GL_DEFAULT_CPU_CAP will be
    returned.

 flags

    OpenVMS usage:mask_quadword
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference
    Options selected for the user capability modification. The flags
    argument is a quadword bit vector wherein a bit corresponds to an
    option. Only the bits specified in the following table are used;
    the remainder of the quadword bits are reserved and must be 0.

    Each option (bit) has a symbolic name, defined by the $CAPDEF
    macro. The flags argument is constructed by performing a logical
    OR operation using the symbolic names of each desired option.

    The following table describes the symbolic name of each option:

    Symbolic Name          Description

    CAP$M_FLAG_DEFAULT_    Indicates that the specified operations
    ONLY                   are to be performed on the global context
                           cell instead of on a specific CPU.
                           This bit supersedes any individual CPU
                           specified in cpu_id but does not override
                           the all active set behavior (CAP$K_ALL_
                           ACTIVE_CPUS). Specifying this bit constant
                           applies this operation to the default
                           startup capabilities for all CPUs booted
                           for the first time.

    CAP$M_FLAG_CHECK_CPU   Determines whether the kernel thread can
                           be left in a nonrunnable state under
                           some circumstances. No operation of
                           this service allows a transition from a
                           runnable to blocked state; however, if
                           the kernel thread is already at a blocked
                           state, this bit determines whether the
                           result of the operation must leave it
                           runnable. If CAP$M_FLAG_CHECK_CPU is set
                           or flags is not specified, the kernel
                           thread is checked to ensure that it can
                           safely run on one of the CPUs in the
                           active set. If CAP$M_FLAG_CHECK_CPU is
                           not set, any state operations on kernel
                           threads already in a blocked state are
                           allowed.