VMS Help System Services, $CRMPSC GFILE 64 (Alpha Only)  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    On Alpha systems, allows a process to create a global disk file
    section and to map a section of its address space to the global
    section.

    This service accepts 64-bit addresses.

    Format

      SYS$CRMPSC_GFILE_64  gs_name_64 ,ident_64 ,file_offset_64

                           ,length_64 ,chan ,region_id_64

                           ,section_offset_64 ,acmode ,flags

                           ,return_va_64 ,return_length_64

                           [,fault_cluster

                           [,start_va_64 [,map_length_64]]]

    C Prototype

      int sys$crmpsc_gfile_64  (void *gs_nam_64, struct _secid

                               *ident_64, unsigned __int64

                               file_offset_64, unsigned __int64

                               length_64, unsigned short

                               int chan, struct _generic_64

                               *region_id_64, unsigned __int64

                               section_offset_64, unsigned int

                               acmode, unsigned int flags, void

                               *(*(return_va_64)), unsigned __int64

                               *return_length_64,...);

1 - 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.

 file_offset_64

    OpenVMS usage:byte offset
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by value
    Byte offset into the file that marks the beginning of the
    section. The file_offset_64 argument is a quadword containing
    this number. If you specify the file_offset_64 argument as 0, the
    section is created beginning with the first byte in the file.

    The file offset specified must be a multiple of virtual disk
    blocks.

 length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by value
    Length, in bytes, of the global disk file section to be created.
    The length specified must be 0 or a multiple of virtual disk
    blocks. If the length specified is 0 or extends beyond the end-
    of-file (EOF), the global disk file section is created up to and
    including the virtual block number that contains EOF.

 chan

    OpenVMS usage:longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Number of the channel on which the file has been accessed. The
    chan argument is a longword containing this number. The access
    mode at which the channel was opened must be equal to or less
    privileged than the access mode of the caller.

    You can use the OpenVMS Record Management Services (RMS) macro
    $OPEN to access a file; the file options parameter in the file
    access block must indicate a user file open (UFO) keyword.

 region_id_64

    OpenVMS usage:region identifier
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by 64 bit reference
    The region ID associated with the region in which to map the
    global disk 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 virtual disk blocks.

 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. The acmode argument is a longword containing the
    access mode.

    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.

    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 characteristics of the global section
    to be created. 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_GFILE_64 service:

    Flag          Description

    SEC$M_CRF     Pages are copy-on-reference.
    SEC$M_GBL     Pages form a global section. By default, this flag
                  is always present in this service and cannot be
                  disabled.
    SEC$M_WRT     Pages form a read/write section. By default, pages
                  form a read-only section.
    SEC$M_DZRO    Pages are demand-zero pages. By default, they are
                  not zeroed when copied.

                  Note that SEC$M_DZRO and SEC$M_CRF cannot both be
                  set and that SEC$M_DZRO set and SEC$M_WRT clear is
                  an invalid combination.
    SEC$M_EXPREG  Pages are mapped into the first available space at
                  the current end of the specified region.
    SEC$M_NO_     Pages cannot overmap existing address space. By
    OVERMAP       default, pages can overmap existing address space.
    SEC$M_PERM    Global section is permanent. By default, global
                  sections are temporary.
    SEC$M_SYSGBL  Pages form a system global section. By default,
                  pages form a group global section.

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

    Upon successful completion of this service, if the
    section_offset_64 argument was specified, the virtual address
    returned in return_va_64 reflects the offset into the global
    section mapped such that the virtual address returned cannot
    be aligned on a CPU-specific page boundary. The virtual address
    returned will always be on an even virtual disk block 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.

    Upon successful completion of this service, the value in the
    return_length_64 argument indicates the amount of created address
    space backed by the section file.

    If the number of disk blocks mapped does not represent an exact
    multiple of CPU-specific pages, the last page in the mapped
    address space will not be completely mapped by the section file.
    In this case, modifying memory beyond the amount indicated by
    return_length_64 can result in the loss of this data.

    Unlike the return_length_64 argument for the $CREATE_GFILE
    service, upon successful completion of this service, the
    return_length_64 argument does not represent the total length
    of the global section created if the section_offset_64 argument
    was specified as nonzero. The value in the section_offset_64
    argument plus the value in the return_length_64 argument is the
    total length of the global disk file section created.

 fault_cluster

    OpenVMS usage:byte count
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Page fault cluster in byte units indicating how many pages
    are to be brought into memory when a page fault occurs for a
    single page. The fault cluster specified will be rounded up to a
    multiple of CPU-specific pages.

    If this argument is specified as 0, the system default page fault
    cluster will be used. If this argument is specified as more than
    the maximum allowed for the system, no error will be returned.
    The systemwide maximum will be used.

 start_va_64

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

    Always refer to the return_va_64 and return_length_64 arguments
    to determine the usable range of virtual addresses mapped.

 map_length_64

    OpenVMS usage:byte count
    type:         quadword unsigned
    access:       read only
    mechanism:    by value
    Length of the global disk file section to be mapped. The length
    specified must be a multiple of virtual disk blocks. If this
    argument is not specified as zero, the global disk section is
    mapped up to and including the last disk block in the section.