Document revision date: 19 July 1999
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OpenVMS Alpha Guide to Upgrading Privileged-Code Applications


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2.4.8 New PCB/KTB Fields

Table 2-3 shows the new PCB and KTB fields as defined by PCBDEF.

Table 2-3 New PCB/KTB Fields
Field Meaning
PCB$K_MAX_KT_COUNT Maximum number of kernel threads
PCB$L_ACTIVE_CPUS CPUs owned by this process
PCB$L_TQUANTUM Per-user thread quantum
PCB$L_MULTITHREAD Maximum thread count
PCB$L_KT_COUNT Current thread count
PCB$L_KT_HIGH Highest KTB vector entry used
PCB$L_KTBVEC KTB vector address
PCB$L_IM_ASTQFL_SPK Special kernel AST queue forward link (head)
PCB$L_IM_ASTQBL_SPK Special kernel AST queue back link (tail)
PCB$L_IM_ASTQFL_K Kernel AST queue forward link (head)
PCB$L_IM_ASTQBL_K Kernel AST queue back link (tail)
PCB$L_IM_ASTQFL_E Executive AST queue forward link (head)
PCB$L_IM_ASTQBL_E Executive AST queue back link (tail)
PCB$L_INITIAL_KTB Initital KTB, overlays KTB$L_PCB
KTB$L_PCB PCB address, overlays PCB$L_INITIAL_KTB
KTB$L_FRED Address of FRED block
KTB$L_PER_KT_AREA Address of per-kernel thread data area
KTB$L_TQUANT Remaining per-user thread quantum
KTB$L_QUANT Remaining per-kernel thread quantum
KTB$L_TM_CALLBACKS Address of thread manager callback vector

2.4.9 CTL$AL_STACK and CTL$AL_STACKLIM

The two arrays containing stack bounds information are now quadwords. The arrays are now CTL$AQ_STACK and CTL$AQ_STACKLIM and are still indexed by access mode. The entries are QUADWORDS.

The arrays pointed to by these two data cells represent only the stack pointers for the initial kernel thread. For a process with multiple kernel threads, the stack arrays are in the per-kernel thread data area. The address of this structure can be found using the KTB$L_PER_KT_AREA field. These fields are defined in PKTADEF. The initial thread has a permanent per-kernel thread, so no distinction is needed between the initial thread and other threads when accessing this data. Table 2-4 shows the stack arrays.

Table 2-4 Stack Arrays
Array Meaning
PKTA$Q_STACK STACK pointer array
PKTA$Q_STACKLIM STACK limit pointer array

2.4.10 Floating-Point Register and Execution Data Block (FRED)

The FRED is defined by FREDDEF. The KTB$L_FRED field in the KTB points to the FRED block. The section of the PHD that contains the HWPCB and floating-point register save area for the initial thread is identical to the layout of the FRED. Therefore, no distinction is needed between the initial thread and other threads when accessing this data.

2.5 Registering Images That Have Version Dependencies

Note

The information in this section does not apply to device drivers, nor to any images that reference the following data structures:
  • BOD
  • CDRP
  • CXB
  • DCBE
  • FDT
  • IRP
  • IRPE
  • PFN
  • PHD
  • UCB
  • VCRP

The need for change in any image (including device drivers, as well as privileged applications linked against SYS$BASE_IMAGE.EXE) is normally detected by a system version check. That check is designed to prevent an application that may need change from producing incorrect results or causing system failures.

The version checks do not necessarily mean that the applications require any change. Digital recommends that you perform some analysis to determine compatibility for privileged images before you run them on Version 7.0 systems.

OpenVMS Alpha Version 7.0 provides an Image Registry facility that may obviate the need for relinking images when you upgrade from previous versions of OpenVMS Alpha. The Image Registry is a central registry of images (including layered products, customer applications, and third-party software) that have version dependencies but have been identified as being compatible with the OpenVMS operating system software. The products in the registry are exempted from version checking.

The Image Registry facility has several benefits, particularly when you have only image files, not source or object files. In addition, it eases version compatibility problems on mixed-version clusters because the same images can be used on all nodes. It also simplifies the addition of third-party software and device drivers to the system.

The registry is a file that contains registered images. These images include main images (images that you can run directly), shared libraries, and device drivers that are identified by name, the image identification string, and the link time of the image. The registered images bypass normal system version checking in the INSTALL, system image loader, and image activator phases. With the Image Registry facility, images for different versions of applications can be registered independently.

Images linked as part of installation need not be registered because they match the version of the running system. However, linking during installation cannot ensure the absence of system version dependencies.

2.5.1 Version Identification (ID) Number Change to Three Subsystems

The OpenVMS executive defines 18 logical subsystems. Each of these subsystems contains its own version identification (ID) number. This modularization makes it possible for OpenVMS releases to include changes to a portion of the executive, impacting only those privileged programs which use that portion of the executive.

For OpenVMS ALpha Version 7.0, the following 3 subsystems have changed, and their version IDs have been incremented:

Developers should check privileged code (that is, any image linked against the system symbol table SYS$BASE_IMAGE.EXE) to determine whether the image is affected by the changes to the subsystems. If the code is affected, the developer should make any necessary changes.


Chapter 3
Replacements for Removed Privileged Symbols

This chapter describes the closest equivalent mechanism to a number of internal routines, data structure cells, and system data cells that have been removed in OpenVMS Alpha Version 7.0.

Each table lists the previous name, any replacements, and a brief explanation.

Important

The internal data structure fields, routines, macros, and data cells described in this chapter should not be interpreted as being part of the documented interfaces that drivers or other privileged software should routinely depend on.

If you were using the removed mechanism correctly, this chapter will assist you in using the closest equivalent in OpenVMS Alpha Version 7.0. However, you should not use this as an opportunity to start using these mechanisms. Doing so is likely to increase the work required to maintain compatibility of your privileged software with future releases of OpenVMS.

3.1 Removed Date Structure Fields

Table 3-1 lists the data structure fields that have been removed as of OpenVMS Alpha Version 7.0.

Table 3-1 Removed Date Structure Fields
Removed Field Replacement Comments
BOD$L_BASEPVA BOD$PQ_BASEPVA 64-bit process virtual address of buffer mapped by the buffer object. See Appendix A.
CDRP$L_AST cdrp$pq_acb64_ast Increased to a quadword and renamed.
CDRP$L_ASTPRM CDRP$Q_A See Appendix A.
CDRP$L_IOSB CDRP$PQ_IOSB See Appendix A.
CPT$L_IOVA CPT$PQ_IOVA Increased to a quadword and renamed.
DMP$M_BITS_12_15 Still have this field. Same value.
DMP$S_BITS_12_15 Still have this field. Same value.
DMP$V_BITS_12_15 Still have this field. Same value.
DYN$C_F64_F64DATA TBS---Dollar  
DYN$C_NET_TIM_TEB DYN$C_NET_TIM_NTEB Renamed because the DECnet structure it indicates (network timer element block) was renamed from TEB to NTEB.
FDT_CONTEXT$L_QIO_R1_VALUE FDT_CONTEXT$Q_QIO_R1_VALUE See Appendix A.
IRP$L_AST IRP$PQ_ACB64_AST Removed to ensure that any reference to the $QIO astadr via a 32-bit address and astprm as a 32-bit value are detected at compile-time or link-time.
IRP$L_ASTPRM IRP$Q_ACB64_ASTPRM Removed to ensure that any reference to the $QIO astadr via a 32-bit address and astprm as a 32-bit value are detected at compile-time or link-time.
IRP$L_IOSB IRP$PQ_IOSB Removed to ensure that any reference to the $QIO iosb via a 32-bit address is detected at compile-time or link-time.
IRPE$L_BCNT1 IRPE$L_BCNT See Appendix A.
IRPE$L_BCNT2 None. Removed.
IRPE$L_BOFF1 IRPE$L_BOFF See Appendix A.
IRPE$L_BOFF2 None. Removed.
IRPE$L_SVAPTE1 IRPE$L_SVAPTE  
IRPE$L_SVAPTE2 None. Removed.
LCKCTX$L_CPLADR LCKCTX$PQ_CPLADR Increased in length to quadword.
LCKCTX$L_CPLPRM LCKCTX$Q_CPLPRM Increased in length to quadword.
LCKCTX$L_CR3 LCKCTX$Q_CR3 Increased in length to quadword.
LCKCTX$L_CR4 LCKCTX$Q_CR4 Increased in length to quadword.
LCKCTX$L_CR5 LCKCTX$Q_CR5 Increased in length to quadword.
LCKCTX$L_CRETADR LCKCTX$PQ_CREADR Increased in length to quadword.
LCKCTX$L_CTX_PRM1 LCKCTX$Q_CTX_PRM1 Increased in length to quadword.
LCKCTX$L_CTX_PRM2 LCKCTX$Q_CTX_PRM2 Increased in length to quadword.
LCKCTX$L_CTX_PRM3 LCKCTX$Q_CTX_PRM3 Increased in length to quadword.
LCKCTX$L_RET1 LCKCTX$PQ_RET1 Increased in length to quadword.
LCKCTX$L_TMP1 LCKCTX$Q_TMP1 Increased in length to quadword.
LKB$C_ACBLEN Removed.  
LKB$K_ACBLEN Removed.  
LKB$L_AST LKB$PQ_AST Increased in length to quadword.
LKB$L_ASTPRM LKB$Q_ASTPRM Increased in length to quadword.
LKB$L_BLKASTADR LKB$PQ_CPLASTADR Increased in length to quadword.
LKB$L_CPLASTADR LKB$PQ_CPLASTADR Increased in length to quadword.
LKB$L_LKSB LKB$PQ_LKSB Increased in length to quadword.
LKB$L_OLDASTPRM LKB$Q_OLDASTPRM Increased in length to quadword.
LKB$L_OLDBLKAST LKB$PQ_OLDBLKAST Increased in length to quadword.
LMB$C_GBL No name change. Value changed from 2 to 3.
LMB$C_PROCESS No name change. Value changed from 3 to 4.
LMB$C_S0 LMB$C_S0S1 Value = 1
LMB$C_SPT LMB$C_SPTW Not guaranteed to be in a dump.
LMB$L_BAD_MEM_END LMB$PQ_BAD_MEM_END Supports a 64-bit address.
LMB$L_BAD_MEM_START LMB$PQ_BAD_MEM_START Supports a 64-bit address.
LMB$L_HOLE_START_VA LMB$PQ_BAD_MEM_START Supports a 64-bit address.
LMB$L_HOLE_TOTAL_PAGES LMB$Q_HOLE_TOTAL_PAGES Supports a 64-bit address.
MMG$C_PTSPACE_OFFSET
MMG$K_PTSPACE_OFFSET
MMG$GL_L1_INDEX Compile-time constant that defined a fixed base address for page table address space. This has been replaced by a run-time mechanism which chooses a base address for page table address space during bootstrap, with the index of level 1 page table entry used to map the page tables stored in the new data cell.
PCB$L_ADB_LINK None Supported a feature that was never implemented.
PCB$L_PSX_ACTPRM PCB$Q_PSX_ACTPRM Increased in length to quadword.
PCB$L_TOTAL_EVTAST None Supported a feature that was never implemented.
PFN$C_ENTRY_SHIFT_SIZE None The size of a single PFN database entry was formerly a power of two. As of Version 7.0, that is no longer true and the symbol was deleted.
PFN$L_PTE   This offset in the PFN database was replaced with a new PTE backpointer mechanism that is capable of supporting page table entries that reside in 64-bit virtual address space. Any code that formerly touched PFN$L_PTE must be recoded to use one of the following macros supplied in LIB.MLB:
  • ACCESS_BACKPOINTER
  • ESTABLISH_BACKPOINTER
  • TEST_BACKPOINTER
  ACCESS_BACKPOINTER Accepts a PFN database entry address and returns a virtual address at which you may access the PTE that maps that PFN. This replaces a fetch of a SVAPTE from PFN$L_PTE, which would subsequently be used as an operand for a memory read or write instruction.
  ESTABLISH_BACKPOINTER Replaces a write of a SVAPTE to PFN$L_PTE.
  TEST_BACKPOINTER Replaces a test for zero in PFN$L_PTE.
PFN$L_REFCNT INCREF
DECREF
This offset in the PFN database was replaced with a differently sized offset that is packed together with other fields in the PFN database. The supplied macro INCREF should be used to replace any existing increment of the value in PFN$L_REFCNT, while DECREF should be used to replace any existing decrement.
PFN$L_WSLX PFN$L_WSLX_QW This offset was renamed to reflect a fundamental change in working set list indexes. Prior to Version 7.0, the working set list index (WSLX) was a longword index. The WSLX has become a quadword index as of Version 7.0, therefore the name of the offset was changed to focus attention on existing code that must be changed to view the value stored at this offset as a quadword index rather than as a longword index.
PHD$C_PHDPAGCTX None Supported a feature that was never implemented.
PHD$L_BAK PHD$L_BAK_ARRAY PHD$L_BAK contained an offset to an internally maintained array which was used to support swapping of the balance slot contents. As of Version 7.0, the implementation of this array changed to better accommodate the balance slot contents. PHD$L_BAK was replaced by PHD$L_BAK_ARRRAY which is the symbolic offset from the start of the process header to where this array begins.
PHD$L_L2PT_VA L2PTE_VA This process header offset formerly contained the system space address of the process's level 2 page table page that was used to map P0 and P1 spaces. As of Version 7.0, the page tables no longer reside in the balance slot, and a process is no longer limited to having only one level 2 page table page. This offset was used to derive addresses of level 2 page table entries. Use the L2PTE_VA macro to derive from a given VA the address of the level 2 PTE that maps that VA.
PHD$L_L3PT_VA
PHD$L_L3PT_VA_P1
PTE_VA These process header offsets formerly contained the system space addresses of the bases of the P0 and P1 page tables that resided in the process's balance slot. As of Version 7.0, the page tables no longer reside in the balance slot, and the conceptual overlap of the P0 and P1 page tables in virtual memory no longer exists. Use the PTE_VA macro to derive from a given VA the address of the level 3 PTE that maps that VA.
PHD$L_P0LENGTH None Different page table layout.
PHD$L_P1LENGTH None Different page table layout.
PHD$L_PSTBASMAX PHD$L_PST_BASE_MAX Contains new-style section index.
PHD$L_PSTBASOFF PHD$L_PST_BASE_OFFSET Name changed.
PHD$L_PSTFREE PHD$L_PST_FREE Contains new-style section index.
PHD$L_PSTLAST PHD$L_PST_LAST Contains new-style section index.
PHD$L_PTWSLELCK
PHD$L_PTWSLEVAL
PFN database These process header offsets formerly contained internal bookkeeping information for managing page table pages for a process. These have been replaced by a bookkeeping mechanism that resides in the PFN database entries for page table pages. It is highly unlikely that anyone is affected by this change.
PHD$L_QUANT KTB$L_QUANT  
PHD$L_WSL CTL$GQ_WSL You can no longer count on WSL (data cell) following PHD, use pointer to WSL in CTL$GQ_WSL instead.
PHD$L_WSLX None WSLX array is no longer in PHD as a result of the new swapper design.
PTE$L_COUNT PTE$L_FREE_COUNT Offset to the number of free PTEs in a free PTE structure.
PTE$L_LINK PTE$Q_INDEX Contains an index to the next free element in the free PTE list. The contents of the field is a quadword index off the base of page table space. Free system PTEs and free global PTEs are linked together in this manner.
PTE$M_SINGLE_SPTE PTE$M_SINGLE_PTE A mask or flag denoting whether a free element describes a single PTE or multiple PTEs.
PTE$V_SINGLE_SPTE None The contents of a free PTE element are AND'ed with PTE$M_SINGLE_PTE to determine whether the element describes a single PTE.


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