Document revision date: 30 March 2001

## OpenVMS System Services Reference Manual

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## $LKWSET_64 (Alpha Only)

> On Alpha systems, locks a range of virtual addresses in the working set; if the pages are not already in the working set, the service brings them in and locks them. A page locked in the working set does not become a candidate for replacement.

> This service accepts 64-bit addresses.

### Format

> SYS$LKWSET_64 start_va_64 ,length_64 ,acmode ,return_va_64 ,return_length_64

### C Prototype

> int sys$lkwset_64 (void *start_va_64, unsigned __int64 length_64, unsigned int acmode, void *(*(return_va_64)), unsigned __int64 *return_length_64);

### Arguments

> #### start_va_64

> OpenVMS usage: | address
> type: | quadword address
> access: | read only
> mechanism: | by value

> The starting virtual address of the pages to be locked in the working set. The specified virtual address will be rounded down to a CPU-specific page boundary.

> #### length_64

> OpenVMS usage: | byte count
> type: | quadword (unsigned)
> access: | read only
> mechanism: | by value

> Length of the virtual address space to be locked in the working set. The specified length will be rounded up to a CPU-specific page boundary so that it includes all CPU-specific pages in the requested range.

> #### acmode

> OpenVMS usage: | access_mode
> type: | longword (unsigned)
> access: | read only
> mechanism: | by value

> Access mode associated with the pages to be locked. 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. For the $LKWSET_64 service to complete successfully, the resultant access mode must be equal to or more privileged than the access mode already associated with the pages to be locked.

> #### return_va_64

> OpenVMS usage: | address
> type: | quadword address
> access: | write only
> mechanism: | by 32- or 64-bit reference

> The lowest process virtual address of the pages locked in the working set. 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.

> #### return_length_64

> OpenVMS usage: | byte count
> type: | quadword (unsigned)
> access: | write only
> mechanism: | by 32- or 64-bit reference

> The length of the virtual address range locked in the working set. 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 in bytes.

### Description

> The Lock Pages in Working Set service locks a range of pages in the working set; if the pages are not already in the working set, it brings them in and locks them. A page locked in the working set does not become a candidate for replacement.

> If the condition value SS$_ACCVIO is returned by this service, a value cannot be returned in the memory locations pointed to by the return_va_64 and return_length_64 arguments. If a condition value other than SS$_ACCVIO is returned, the returned address and returned length indicate the pages that were successfully locked before the error occurred. If no pages were locked, the return_va_64 argument will contain the value -1, and a value cannot be returned in the memory location pointed to by the return_length_64 argument.

> Global pages with write access cannot be locked into the working set.

> Required Privileges

> None

> Required Quota

> None

> Related Services

> $LKWSET, $ULWSET, $ULWSET_64

### Condition Values Returned

> SS$_WASCLR | The service completed successfully. All of the specified pages were previously unlocked.
> SS$_WASSET | The service completed successfully. At least one of the specified pages was previously locked in the working set.
> SS$_ACCVIO | The return_va_64 or return_length_64 argument cannot be written by the caller, or an attempt was made to lock pages by a caller whose access mode is less privileged than the access mode associated with the pages.
> SS$_LKWSETFUL | The locked working set is full. If any more pages are locked, not enough dynamic pages will be available to continue execution.
> SS$_NOPRIV | No privilege; global pages with write access cannot be locked into the working set.
> SS$_PAGNOTINREG | A page in the specified range is not within the specified region.
> SS$_PAGOWNVIO | The pages could not be locked because the access mode associated with the call to $LKWSET_64 was less privileged than the access mode associated with the pages that were to be locked.

## $MGBLSC

> Establishes a correspondence between pages (maps) in the virtual address space of the process and physical pages occupied by a global section.

### Format

> SYS$MGBLSC inadr ,[retadr] ,[acmode] ,[flags] ,gsdnam ,[ident] ,[relpag]

### C Prototype

> int sys$mgblsc (struct _va_range *inadr, struct _va_range *retadr, unsigned int acmode, unsigned int flags, void *gsdnam, struct _secid *ident, unsigned int relpag);

### Arguments

> #### inadr

> OpenVMS usage: | address_range
> type: | longword (unsigned)
> access: | read only
> mechanism: | by reference

> Starting and ending virtual addresses into which the section is to be mapped. The inadr argument is the address of a 2-longword array containing, in order, the starting and ending process virtual addresses. Only the virtual page number portion of each virtual address is used to specify which pages are to be mapped; the low-order byte-within-page bits are ignored for this purpose.

> The interpretation of the inadr argument depends on the setting of SEC$M_EXPREG in the flags argument and on whether you are using an Alpha or a VAX system. The two system types are discussed separately in this section.

> Alpha System Usage

> On Alpha systems, if you do not set the SEC$M_EXPREG flag, the inadr argument specifies the starting and ending virtual addresses of the region to be mapped. Addresses in system space are not allowed. The addresses must be aligned on CPU-specific pages; no rounding to CPU-specific pages occurs. The lower address of the inadr argument must be on a CPU-specific page boundary and the higher address of the inadr argument must be 1 less than a CPU-specific boundary, thus forming a range, from lowest to highest, of address bytes. You can use the SYI$_PAGE_SIZE item code in the $GETSYI system service to set the inadr argument to the proper values. You do this to avoid programming errors that might arise because of incorrect programming assumptions about page sizes.

> If, on the other hand, you do set the SEC$M_EXPREG flag, indicating that the mapping should take place using the first available space in a particular region, the inadr argument is used only to indicate the desired region: the program region (P0) or the control region (P1).

> Caution Mapping into the P1 region is generally discouraged, but, if done, must be executed with extreme care. Since the user stack is mapped in P1, it is possible that references to the user stack might inadvertently read or write the pages mapped with $CRMPSC.

> When the SEC$M_EXPREG flag is set, the second inadr longword is ignored, while bit 30 (the second most significant bit) of the first inadr longword is used to determine the region of choice. If the bit is clear, P0 is chosen; if the bit is set, P1 is chosen. On Alpha systems, bit 31 (the most significant bit) of the first inadr longword must be 0. To ensure compatibility between VAX and Alpha systems when you choose a region, Compaq recommends that you specify, for the first inadr longword, any virtual address in the desired region.

> VAX System Usage

> On VAX systems, if you do not set the SEC$M_EXPREG flag, the inadr argument specifies the starting and ending virtual addresses of the region to be mapped. Addresses in system space are not allowed. If the starting and ending virtual addresses are the same, a single page is mapped.

> Note If the SEC$M_EXPREG flag is not set, Compaq recommends that the inadr argument always specify the entire virtual address range, from starting byte address to ending byte address. This ensures compatibility between VAX and Alpha systems.

> If, on the other hand, you do set the SEC$M_EXPREG flag, indicating that the mapping should take place using the first available space in a particular region, the inadr argument is used only to indicate the desired region: the program region (P0) or the control region (P1).

> Caution Mapping into the P1 region is generally discouraged, but, if done, must be executed with extreme care. Since the user stack is mapped in P1, it is possible that references to the user stack might inadvertently read or write the pages mapped with $CRMPSC.

> When the SEC$M_EXPREG flag is set, the second inadr longword is ignored, while bit 30 (the second most significant bit) of the first inadr longword is used to determine the region of choice. If the bit is clear, P0 is chosen; if the bit is set, P1 is chosen. On VAX systems, bit 31 (the most significant bit) of the first inadr longword is ignored. To ensure compatibility between VAX and Alpha systems when you choose a region, Compaq recommends that you specify, for the first inadr longword, any virtual address in the desired region.

> #### retadr

> OpenVMS usage: | address_range
> type: | longword (unsigned)
> access: | write only
> mechanism: | by reference

> Starting and ending process virtual addresses into which the section was actually mapped by $MGBLSC. The retadr argument is the address of a 2-longword array containing, in order, the starting and ending process virtual addresses.

> On Alpha systems, the retadr argument returns the starting and ending addresses of the usable range of addresses. This might differ from the total amount mapped. The retadr argument is required when the relpag argument is specified. If the section being mapped does not completely fill the last page used to map the section, the retadr argument indicates the highest address that actually maps the section. If the relpag argument is used to specify an offset into the section, the retadr argument reflects the offset.

> #### acmode

> OpenVMS usage: | access_mode
> type: | longword (unsigned)
> access: | read only
> mechanism: | by value

> Access mode to be associated with the pages mapped into the process virtual address space. The acmode argument is a longword containing the access mode. The $PSLDEF macro defines symbols for the four access modes.

> The most privileged access mode used is the access mode of the caller.

> #### 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 wherein a bit when set specifies the corresponding option.

> The $SECDEF macro defines symbolic names for the flag bits. You construct the flags argument by specifying the symbolic names of each desired option in a logical OR operation.

> The following table describes each flag option:

> Flag Option | Description
> --- | ---
> SEC$M_WRT | Map the section with read/write access. By default, the section is mapped with read-only access. If SEC$M_WRT is specified and the section is not copy-on-reference, write access is required.
> SEC$M_SYSGBL | Map a system global section. By default, the section is a group global section.
> SEC$M_EXPREG | Map the section into the first available virtual address range. By default, the section is mapped into the range specified by the inadr argument. See the inadr argument description for a complete explanation of how to set the SEC$M_EXPREG flag.

> #### gsdnam

> OpenVMS usage: | section_name
> type: | character-coded text string
> access: | read only
> mechanism: | by descriptor--fixed-length string descriptor

> Name of the global section. The gsdnam argument is the address of a character string descriptor pointing to this name string.

> For group global sections, the operating system interprets the group UIC as part of the global section name; thus, the names of global sections are unique to UIC groups. Further, all global section names are implicitly qualified by their identification fields.

> 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

> OpenVMS usage: | section_id
> type: | quadword (unsigned)
> access: | read only
> mechanism: | by reference

> Identification value specifying the version number of a global section and, for processes mapping to an existing global section, the criteria for matching the identification. The ident argument is the address of a quadword structure containing three fields.

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

> 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.

> The version number is in the second longword and contains two fields: a minor identification in the low-order 24 bits and a major identification in the high-order 8 bits.

> If you do not specify ident or specify it as the value 0 (the default), the version number and match control fields default to the value 0.

> #### relpag

> OpenVMS usage: | longword_unsigned
> type: | longword (unsigned)
> access: | read only
> mechanism: | by value

> Relative page number within the section of the first page to be mapped. The relpag argument is a longword containing this number.

> On Alpha systems, the relpag argument is interpreted as an index into the section file, measured in pagelets for a file-backed section or CPU-specific pages for a PFN-mapped section.

> On Alpha and VAX systems, if you do not specify relpag or specify it as the value 0 (the default), the global section is mapped beginning with the first virtual block in a file-backed section or the first CPU-specific page in a PFN-mapped section.

### Description

> The Map Global Section service establishes a correspondence between pages (maps) in the virtual address space of the process and physical pages occupied by a global section. The protection mask specified at the time the global section is created determines the type of access (for example, read/write or read only) that a particular process has to the section.

> When $MGBLSC maps a global section, it adds pages to the virtual address space of the process. The section is mapped from a low address to a high address, whether the section is mapped in the program or control region.

> If an error occurs during the mapping of a global section, the return address array, if specified, indicates the pages that were successfully mapped when the error occurred. If no pages were mapped, both longwords of the return address array contain the value --1.

> Required Access or Privileges

> Read access is required. If the SEC$M_WRT flag is specified, write access is required.

> Required Quota

> The working set quota (WSQUOTA) of the process must be sufficient to accommodate the increased size of the virtual address space when the $MGBLSC service maps a section.

> If the section pages are copy-on-reference, the process must also have sufficient paging file quota (PGFLQUOTA).

> This system service causes the working set of the calling process to be adjusted to the size specified by the working set quota (WSQUOTA). If the working set size of the process is less than quota, the working set size is increased; if the working set size of the process is greater than quota, the working set size is decreased.

> Related Services

> $ADJSTK, $ADJWSL, $CRETVA, $CRMPSC, $DELTVA, $DGBLSC, $EXPREG, $LCKPAG, $LKWSET, $PURGWS, $SETPRT, $SETSTK, $SETSWM, $ULKPAG, $ULWSET, $UPDSEC, $UPDSECW

> For more information, refer to the chapter on memory management in the OpenVMS Programming Concepts Manual.

### Condition Values Returned

> SS$_NORMAL | The service completed successfully.
> SS$_ACCVIO | The input address array, the global section name or name descriptor, or the section identification field cannot be read by the caller; or the return address array cannot be written by the caller.
> SS$_ENDOFFILE | The starting virtual block number specified is beyond the logical end-of-file.
> SS$_EXQUOTA | The process exceeded its paging file quota, creating copy-on-reference pages.
> SS$_INSFWSL | The working set limit of the process is not large enough to accommodate the increased virtual address space.
> SS$_INVARG | Invalid argument specified to service. Common sources are the incorrect specification of relpag or the values in the inadr array.
> SS$_IVLOGNAM | The global section name has a length of 0 or has more than 43 characters.
> SS$_IVSECFLG | You set a reserved flag.
> SS$_IVSECIDCTL | The match control field of the global section identification is invalid.
> SS$_NOPRIV | The file protection mask specified when the global section was created prohibits the type of access requested by the caller; or a page in the input address range is in the system address space.
> SS$_NOSHPTS | The region ID of a shared page-table region was specified.
> SS$_NOSUCHSEC | The specified global section does not exist.
> SS$_PAGOWNVIO | A page in the specified input address range is owned by a more privileged access mode.
> SS$_SECREFOVF | The maximum number of references for a global section has been reached (2,147,483,647).
> SS$_TOOMANYLNAM | Logical name translation of the gsdnam string exceeded the allowed depth.
> SS$_VA_IN_USE | The existing underlying page cannot be deleted because it is associated with a buffer object.
> SS$_VASFULL | The virtual address space of the process is full; no space is available in the page tables for the pages created to contain the mapped global section.

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