Copyright Digital Equipment Corp. All rights reserved.
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$M_SYSGBL Pages form a system global section. By default,
pages form a group global section.
All other bits in the flags argument are reserved for future
use by VSI and should be specified as 0. The condition value
SS$_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.