VMS Help  —  System Services, $CRMPSC GDZRO 64 (Alpha and Integrity servers), Arguments
 gs_name_64

    OpenVMS usage:section_name
    type:         character-coded text string
    access:       read only
    mechanism:    by 32- or 64-bit descriptor-fixed-length string
                  descriptor
    Name of the global section. The gs_name_64 argument is the 32-
    or 64-bit virtual address of a naturally aligned 32- or 64-bit
    string descriptor pointing to this name string.

 ident_64

    OpenVMS usage:section_id
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference
    Identification value specifying the version number of a global
    section. The ident_64 argument is a quadword containing three
    fields. The ident_64 argument is the 32- or 64-bit virtual
    address of a naturally aligned quadword that contains the
    identification value.

    The first longword specifies the matching criteria in its low-
    order 2 bits. The valid values, symbolic names by which they can
    be specified, and their meanings are as follows:

           Symbolic
    Value  Name           Match Criteria

    0      SEC$K_MATALL   Match all versions of the section.
    1      SEC$K_MATEQU   Match only if major and minor
                          identifications match.
    2      SEC$K_MATLEQ   Match if the major identifications are
                          equal and the minor identification of the
                          mapper is less than or equal to the minor
                          identification of the global section.

    When a section is mapped at creation time, the match control
    field is ignored. If you specify the ident_64 argument as 0, the
    version number and match control fields default to 0.

    The version number is in the second longword. The version number
    contains two fields: a minor identification in the low-order 24
    bits and a major identification in the high-order 8 bits. You
    can assign values for these fields by installation convention to
    differentiate versions of global sections. If no version number
    is specified when a section is created, processes that specify a
    version number when mapping cannot access the global section.

 prot

    OpenVMS usage:file_protection
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Protection to be applied to the global demand-zero section. The
    mask contains four 4-bit fields. Bits are read from right to left
    in each field.

    Refer to the VSI OpenVMS System Services Reference Manual to view
    the diagram depicting the mask.

    Cleared bits indicate that read, write, execute, and delete
    access, in that order, are granted to the particular category
    of user. Only read, write, and execute access are meaningful
    for section protection. Delete access bits are ignored. Read
    access also grants execute access for those situations where
    execute access applies. If zero is specified, read access and
    write access are granted to all users.

 length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by value
    Length, in bytes, of the global demand-zero section to be
    created. The length_64 must be specified as a multiple of the
    CPU-specific page size. A length of 0 cannot be specified.

                                   NOTE

       Creating a memory-resident global section with shared page
       table does not imply that the global section must have an
       even multiple of CPU-specific page table pages. The global
       section might not fully use the last page table page.

 region_id_64

    OpenVMS usage:region identifier
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference
    The region ID associated with the region to map the global page
    file section.

    The file VADEF.H in SYS$STARLET_C.TLB and the $VADEF macro in
    STARLET.MLB define a symbolic name for each of the three default
    regions in P0, P1, and P2 space.

    The following region IDs are defined:

    Symbol     Region

    VA$C_P0    Program region
    VA$C_P1    Control region
    VA$C_P2    64-bit program region

    Other region IDs, as returned by the $CREATE_REGION_64 service,
    can be specified.

 section_offset_64

    OpenVMS usage:byte offset
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by value
    Offset into the global section to start mapping into the
    process's virtual address space. The offset specified must be
    a multiple of a CPU-specific page size.

    If a shared page table region is specified by the region_id_
    64 argument, section_offset_64 must be an even multiple of
    the larger of the number of bytes that can be mapped by a CPU-
    specific page. For Integrity server systems, the alignment of
    section offsets must also be an integer multiple of the page size
    used to map VA space at this offset.

    VSI recommends that you avoid any partial mapping of memory-
    resident sections when you use shared page tables on Integrity
    server systems. If you cannot avoid this, set bit 4 in the system
    parameter MMG_CTLFLAGS to limit the effective page size to the
    number of bytes that can be mapped by a page.

 acmode

    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode that is to be the owner of the pages created during
    the mapping. This access mode is also the read access mode
    and the write access mode. The acmode argument is a longword
    containing the access mode.

    If the memory-resident global section is created with shared
    page tables, this is the access mode that is stored in the owner,
    read, and write fields of the corresponding shared page table
    entries (PTEs).

    The $PSLDEF macro in STARLET.MLB and the file PSLDEF.H in
    SYS$STARLET_C.TLB define the following symbols and their values
    for the four access modes:

    Value      Symbolic Name      Access Mode

    0          PSL$C_KERNEL       Kernel
    1          PSL$C_EXEC         Executive
    2          PSL$C_SUPER        Supervisor
    3          PSL$C_USER         User

    The most privileged access mode used is the access mode of the
    caller. The calling process can delete pages only if those pages
    are owned by an access mode equal to or less privileged than the
    access mode of the calling process.

    Address space cannot be created within a region that has a create
    mode associated with it that is more privileged than the caller's
    mode. The condition value SS$_IVACMODE is returned if the caller
    is less privileged than the create mode for the region.

 flags

    OpenVMS usage:mask_longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Flag mask specifying the type of the global section to be created
    as well as its characteristics. The flags argument is a longword
    bit vector in which each bit corresponds to a flag. The $SECDEF
    macro and the SECDEF.H file define a symbolic name for each
    flag. You construct the flags argument by performing a logical
    OR operation on the symbol names for all desired flags.

    The following table describes each flag that is valid for the
    $CRMPSC_GDZRO_64 service:

    Flag          Description

    SEC$M_DZRO    Pages are demand-zero pages. By default, this flag
                  is always present in this service and cannot be
                  disabled.

    SEC$M_EXPREG  Pages are mapped into the first available space at
                  the current end of the specified region.

                  If the /ALLOCATE qualifier was specified when the
                  global section was registered in the Reserved
                  Memory Registry, virtually aligned addresses
                  after the first available space are chosen for
                  the mapping.

    SEC$M_GBL     Pages form a global section. By default, this flag
                  is always present in this service and cannot be
                  disabled.

    SEC$M_NO_     Pages cannot overmap existing address space.
    OVERMAP

    SEC$M_PERM    Global section is permanent.

    SEC$M_RAD_    When set, the argument rad_mask is used as a mask
    HINT          of RADs from which to allocate memory. See the rad_
                  mask argument description for more information.

    SEC$M_READ_   Create shared table pages for the section that
    ONLY_SHPT     allow read access only.

    SEC$M_SHMGS   Create a shared-memory global section.

    SEC$M_SYSGBL  Pages form a system global section. By default,
                  pages form a group global section.

    SEC$M_MRES    Pages form a memory-resident section. By default,
                  this page is always present in this service and
                  cannot be disabled.

    SEC$M_WRT     Pages form a read/write section. By default, this
                  flag is always present in this service and cannot
                  be disabled.

    All other bits in the flags argument are reserved for future
    use by VSI and should be specified as 0. The condition value
    SS$_IVSECFLG is returned if any undefined bits are set or if
    an invalid combination of flags is set.

 return_va_64

    OpenVMS usage:address
    type:         quadword address
    access:       write only
    mechanism:    by 32- or 64-bit reference
    The lowest process virtual address into which the global demand-
    zero section was mapped. The return_va_64 argument is the 32- or
    64-bit virtual address of a naturally aligned quadword into which
    the service returns the virtual address.

    If a shared page table region is specified by the region_id_64
    argument and the SEC$M_EXPREG flag is set, the returned virtual
    address is aligned to a CPU-specific page table page boundary.

 return_length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by 32- or 64-bit reference
    The 32- or 64-bit virtual address of a naturally aligned quadword
    into which the service returns the length of the virtual address
    range mapped in bytes.

 start_va_64

    OpenVMS usage:address
    type:         quadword address
    access:       read only
    mechanism:    by value
    The starting virtual address to map the memory-resident global
    section. The specified virtual address must be a CPU-specific
    page aligned address. If the flag SEC$M_EXPREG is specified, the
    start_va_64 argument must not be specified or must be specified
    as 0. If SEC$M_EXPREG is set and the start_va_64 argument is
    nonzero, the condition value SS$_IVSECFLG is returned.

    If SEC$M_EXPREG is clear, start_va_64 is nonzero, and a shared
    page table region is specified, the specified starting address
    must be aligned to a natural page table page boundary; otherwise,
    the condition value SS$_VA_NOTPAGALGN is returned.

    If the /ALLOCATE qualifier was specified when the memory-resident
    global section was registered in the Reserved Memory Registry
    and start_va_64 is aligned to a multiple of CPU-specific pages
    appropriate for taking advantage of granularity hints then
    granularity hints are used to map to the global section:

    o  On Alpha systems, granularity hints mean multiples of pages,
       regardless of page size. The multiples 8, 64, and 512 pages
       are architected.

    o  On Integrity server systems, OpenVMS initially supports page
       sizes of 64KB, 256KB, and 4MB instead of granularity hints.
       Additional pages sizes will be supported in the future.

    If the flag VA$M_SHARED_PTS is set and this argument is
    specified, the specified starting address must be aligned to
    the larger of a natural page table boundary or to the largest
    possible page size used to map the section. If the alignment is
    less than a page table boundary, the $CREATE_REGION_64 service
    returns an error. If the alignment is less than the largest page
    size used in the section, an error might be returned when you
    attempt to map the section.

    If you do not specify a starting address, OpenVMS automatically
    ensures correct alignment.

 map_length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by value
    Length of the memory-resident global section to be mapped. The
    length specified must be a multiple of CPU-specific pages. If
    this argument is not specified or is specified as zero, the
    global file section is mapped up to and including the last page
    in that section.

    If a shared page table region is specified by the region_id_64
    argument, map_length_64 must be an even multiple of the number
    of bytes that can be mapped by a CPU-specific page table page or
    must include the last page within the global section.

 reserved_length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       write only
    mechanism:    32- or 64-bit reference
    Length, in bytes, of the global section as currently registered
    in the Reserved Memory Registry. The reserved_length_64 argument
    is the 32- or 64-bit virtual address of a naturally aligned
    quadword into which the service returns the reserved length.

    If reserved_length_64 is not specified or is specified as 0, no
    reserved length is returned to the caller.

    If the memory-resident global section is not registered,
    reserved_length_64 is written with the value 0.

 rad_mask

    OpenVMS usage:mask_quadword
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by value
    Use the rad_mask argument to specify from which RADs to allocate
    memory. Currently only one bit may be set. The specified RAD
    must contain memory. This argument is only a hint. Memory may be
    obtained from other RADs if no free memory is available at the
    time of allocation.

    The rad_mask argument is considered only if the SEC$M_RAD_HINT
    flag is specified. Otherwise, this argument is ignored.

    On a system that does not support resource affinity domains
    (RADs), specifying 1 for the rad_mask argument is allowed.

    RAD is supported on AlphaServer GS series systems and starting
    from OpenVMS Version 8.4, support is extended to NUMA capable
    Integrity servers.
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