System Services, $MGBLSC 64 (Alpha Only), Arguments
*Conan The Librarian
gs_name_64 OpenVMS usage:section_name type: character-coded text string access: read only mechanism: by 32- or 64-bit descriptor-fixed-length string descriptor Name of the global section. The gs_name_64 argument is the 32- or 64-bit virtual address of a naturally aligned 32-bit or 64-bit string descriptor pointing to this name string. You can specify any name from 1 to 43 characters. All processes mapping to the same global section must specify the same name. Note that the name is case sensitive. Use of characters valid in logical names is strongly encouraged. Valid values include alphanumeric characters, the dollar sign ($), and the underscore (_). If the name string begins with an underscore (_), the underscore is stripped and the resultant string is considered to be the actual name. Use of the colon (:) is not permitted. Names are first subject to a logical name translation, after the application of the prefix GBL$ to the name. If the result translates, it is used as the name of the section. If the resulting name does not translate, the name specified by the caller is used as the name of the section. Additional information on logical name translations and on section name processing is available in the OpenVMS Programming Concepts Manual. 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 two 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$K_MATLEQ Match if the major identifications are equal and the minor identification of the mapper is less than or equal to the minor identification of the global section. If you specify the ident_64 argument as 0, the version number and match control fields default to 0. The version number is in the second longword. The version number contains two fields: a minor identification in the low-order 24 bits and a major identification in the high-order 8 bits. You can assign values for these fields by installation convention to differentiate versions of global sections. If no version number is specified when a section is created, processes that specify a version number when mapping cannot access the global section. region_id_64 OpenVMS usage:region identifier type: quadword (unsigned) access: read only mechanism: by 32- or 64-bit reference The region ID associated with the region to map the global section. The file VADEF.H in SYS$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 $CREATE_REGION_64 service, can be specified. section_offset_64 OpenVMS usage:byte offset type: quadword (unsigned) access: read only mechanism: by value Offset into the global section at which to start mapping into the process's virtual address space. If a map to a global disk file section is being requested, the section_offset_64 argument specifies an even multiple of disk blocks. If a map to a global page file or demand-zero section is being requested, the section_offset_64 argument specifies an even multiple of CPU-specific pages. If zero is specified, the global section is mapped beginning with the first page of the section. If the region_id_64 argument specifies a shared page table region, section_offset_64 must be an even multiple of pages mapped by a page table page. length_64 OpenVMS usage:byte count type: quadword (unsigned) access: read only mechanism: by value Length, in bytes, of the desired mapping of the global disk file section. If a map to a global section is being requested, the length_64 argument must specify an even multiple of disk blocks. If a map to a global page file or demand-zero section is being requested, the length_64 argument must specify an even multiple of CPU- specific pages. If zero is specified, the size of the disk file is used. If a shared page-table region is specified by the region_id_64 argument, length_64 must be an even multiple of the number of bytes that can be mapped by a CPU-specific page-table page or must include the last page within the memory-resident global section. acmode OpenVMS usage:access_mode type: longword (unsigned) access: read only mechanism: by value Access mode that is to be the owner of the pages created during the mapping. This is also the read access mode and, if the SEC$M_ WRT flag is specified, the write access mode. 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 options for the operation. 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 $MGBLSC_64 service: Flag Description SEC$M_EXPREG Pages are mapped into the first available space at the current end of the specified region. If /ALLOCATE was specified when the memory-resident global section was registered in the Reserved Memory Registry, virtually aligned addresses after the first available space are chosen for the mapping. It the region_id_64 argument specifies a shared page-table region, the first available space is round up to the beginning of the next CPU-specific page-table page. 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$M_SHMGS On OpenVMS Galaxy systems, create a shared-memory global section. SEC$M_SYSGBL The global section map is a system global section. By default, the section is a group global section. SEC$M_WRT Map the section with read/write access. All other bits in the flags argument are reserved for future use by Compaq and should be specified as 0. The condition value SS$_IVSECFLG is returned if any undefined bits are set or if an attempt is made to use the SEC$M_PAGFIL flag, which applies only to the creation of a page-file backed section. return_va_64 OpenVMS usage:address type: quadword address access: write only mechanism: by 32- or 64-bit reference The process virtual address into which the global disk or page 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 the return_va_64 argument 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 length of the usable virtual address range mapped. The return_length_64 argument is 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 might differ from the total amount of virtual address space mapped. The value in the return_va_64 argument plus the value in the return_length_64 argument indicates the address of the first byte beyond the end of the mapping of the global disk file section. If the value in the section_offset_64 argument plus the value in the length_64 argument did not specify to map the entire global section, this byte can be located at an even virtual disk block boundary within the last page of the mapping. If the section being mapped does not completely fill the last page used to represent the global disk file section, this byte can be mapped into your address space; however, it is not backed up by the disk file. start_va_64 OpenVMS usage:address type: quadword address access: read only mechanism: by value The starting virtual address to which to map the 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 the region_id_64 argument specifies a shared page-table region, start_va_64 must be aligned to a CPU-specific page-table page boundary.