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HP OpenVMS System Analysis Tools Manual

HP OpenVMS System Analysis Tools Manual
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MODIFY DUMP

Allows a given byte, word, longword, or quadword in the dump file to be modified.

Format

MODIFY DUMP {/BLOCK=n/OFFSET=n|/NEXT} [/CONFIRM=n] {/BYTE|/WORD|/LONGWORD (d)|/QUADWORD} value

Parameter

value

New value deposited in the specified location in the dump file.

Qualifiers

/BLOCK=n

Indicates block number to be modified. Required unless the /NEXT qualifier is given.

/OFFSET=n

Indicates byte offset within block to be modified. Required unless the /NEXT qualifier is given.

/NEXT

Indicates that the byte or bytes immediately following the location altered by the previous MODIFY DUMP command are to be modified. Used instead of the /BLOCK=n and /OFFSET=n qualifiers.

/CONFIRM=n

Checks existing contents of location to be modified.

/BYTE

Indicates that only a single byte is to be replaced.

/WORD

Indicates that a word is to be replaced.

/LONGWORD

Indicates that a longword is to be replaced. This is the default.

/QUADWORD

Indicates that a quadword is to be replaced.

Description

The MODIFY DUMP command is used on a dump file that cannot be analyzed without specifying the /OVERRIDE qualifier on the ANALYZE/CRASH_DUMP command. You can use the MODIFY DUMP command to correct the problem that prevents normal analysis of a dump file. You can only use the MODIFY DUMP command when you have invoked SDA with the ANALYZE/CRASH_DUMP/OVERRIDE command.

Important
This command is not intended for general use. It is provided for the benefit of HP support personnel when investigating crash dumps that cannot be analyzed in other ways.

If the block being modified is part of either the dump header, the error log buffers, or the compression map, the changes made are not seen when you issue the appropriate SHOW DUMP command, unless you first exit from SDA and then reissue the ANALYZE/CRASH_DUMP command.

The MODIFY DUMP command sets a bit in the dump header to indicate that the dump has been modified. Subsequent ANALYZE/CRASH_DUMP commands issued to that file produce the following warning message: 


%SDA-W-DUMPMOD, dump has been modified

Examples

#1 

SDA>> MODIFY DUMP/BLOCK=10/OFFSET=100/WORD FF

This example shows the dump file modified with the word at offset 100 in block 00000010 replaced by 00FF.

#2 

SDA>> MODIFY DUMP/BLOCK=10/OFFSET=100/WORD 0/CONFIRM=EE
%SDA-E-NOMATCH, expected value does not match value in dump; dump not updated

This example shows what happens when the actual word value of 00FF at offset 100 in block 00000010 does not match the given value of 00EE.

#3 

SDA>> MODIFY DUMP/BLOCK=10/OFFSET=100/WORD 0/CONFIRM=FF

This example shows the dump file modified with a word value of 00FF at offset 100 in block 00000010 replaced by 0000.

READ

Loads the global symbols contained in the specified file into the SDA symbol table.

Format

READ [/[NO]LOG|/RELOCATE =expression|/SYMVA=expression]
{/EXECUTIVE [directory spec]|/FORCE filespec
|/IMAGE filespec|filespec}

Parameters

directory-spec

Name of the directory containing the loadable images of the executive. This parameter defaults to SDA$READ_DIR, which is a search list of SYS$LOADABLE_IMAGES and SYS$LIBRARY.

filespec

Name of the device, directory, and file that contains the file from which you want to read global symbols. The filespec defaults to SYS$DISK:[default-dir]filename.type, where SYS$DISK and [default-dir] represent the disk and directory specified in your last DCL command SET DEFAULT. If no type has been given in filespec, SDA first tries .STB and then .EXE.

If no device or directory is given in the file specification, and the file specification is not found in SYS$DISK:[default_dir], then SDA attempts to open the file SDA$READ_DIR:filename.type. If no type has been given in filespec, SDA first tries .STB and then .EXE.

If the file name is the same as that of an execlet or image, but the symbols in the file are not those of the execlet or image, then you must use the /FORCE qualifier, and optionally /RELOCATE and /SYMVA qualifiers, to tell SDA how to interpret the symbols in the file.

The READ command accepts quoted filenames for access to images on ODS-5 disks with lowercase or compound characters in their names.

Qualifiers

/EXECUTIVE directory-spec

Reads into the SDA symbol table all global symbols and global entry points defined within all loadable images that make up the executive. For all the execlets in the system, SDA reads the .STB or .EXE files in the requested directory.

/FORCE filespec

Forces SDA to read the symbols file, regardless of what other information or qualifiers are specified. If you do not specify the /FORCE qualifier, SDA may not read the symbols file if the specified filespec matches the image name in either the executive loaded images or the current processes activated image list, and one of the following conditions is true:

The use of /FORCE [/SYMVA=addr][/RELOCATE=addr] filespec is a variant of the /IMAGE qualifier and avoids fixing up the symbols to match an image of the same name.

/IMAGE filespec

Searches the executive loaded image list and the current process activated image list for the image specified by filespec. If the image is found, the symbols are read in using the image symbol vector (if there is one) and either slicing or relocation information.

This is the preferred way to read in the .STB files produced by the linker. These .STB files contain all universal symbols, unless SYMBOL_TABLE=GLOBAL is in the linker options file, in which case the .STB file contains all universal and global symbols.

/LOG
/NOLOG (D)

The /LOG qualifier causes SDA to output the %SDA-I-READSYM message for each symbol table file it reads. You can specify the /LOG qualifier with any other combination of parameters and qualifiers.

The /NOLOG qualifier suppresses the output of the %SDA-I-READSYM messages. This is the default. You can specify the /NOLOG qualifier with any other combination of parameters and qualifiers.

/RELOCATE=expression

Changes the relative addresses of the symbols to absolute addresses by adding the value of expression to the value of each symbol in the symbol table file to be read. This qualifier changes those addresses to absolute addresses in the address space into which the dump is mapped.

The relocation only applies to symbols with the relocate flag set. All universal symbols must be found in the symbol vector for the image. All constants are read in without any relocation.

If the image is sliced (image sections are placed in memory at different relative offsets than how the image is linked), then the /RELOCATE qualifier does not work. SDA compares the file name used as a parameter to the READ command against all the image names in the executive loaded image list and the current processes activated image list. If a match is found, and that image contains a symbol vector, an error results. At this point you can either use the /FORCE qualifier or the /IMAGE qualifier to override the error.

/SYMVA=expression

Informs SDA whether the absolute symbol vector address is for a shareable image (SYS$PUBLIC_VECTORS.EXE) or base system image (SYS$BASE_IMAGE.EXE). All symbols found in the file with the universal flag are found by referencing the symbol vector (that is, the symbol value is a symbol vector offset).

Description

The READ command symbolically identifies locations in memory and the definitions used by SDA for which the default files (SDA$READ_DIR:SYS$BASE_IMAGE.EXE and SDA$READ_DIR:REQSYSDEF.STB) provide no definition. In other words, the required global symbols are located in modules and symbol tables that have been compiled and/or linked separately from the executive. SDA extracts no local symbols from the files.

The file specified in the READ command can be the output of a compiler or assembler (for example, an .OBJ file).

Note
The READ command can read both OpenVMS Alpha and OpenVMS I64 format files. Do not use READ to read files that contain symbols specific to another architecture, as this might change the behavior of other SDA commands for the current architecture.

Most often the file is provided in SYS$LOADABLE_IMAGES. Many SDA applications, for instance, need to load the definitions of system data structures by issuing a READ command specifying SYSDEF.STB. Others require the definitions of specific global entry points within the executive image.

The files in SYS$LOADABLE_IMAGES define global locations within executive images, including those listed in Table 4-1. The actual list of executive images used varies, depending on platform type, devices, and the settings of several system parameters.

Table 4-1 Modules Defining Global Locations Within Executive Images
File Contents
ACME.EXE $ACM system service
CNX$DEBUG.EXE Connection Manager trace routines
DDIF$RMS_EXTENSION.EXE Support for Digital Document Interchange Format (DDIF) file operations
ERRORLOG.STB Error-logging routines and system services
EXCEPTION.STB 1 Bugcheck and exception-handling routines and those system services that declare condition and exit handlers
EXEC_INIT.STB Initialization code
F11BXQP.STB File system support
FC$GLOGALS.STB Fibrechannel symbols
IMAGE_MANAGEMENT.STB Image activator and the related system services
IO_ROUTINES.STB 1 $QIO system service, related system services (for example, $CANCEL and $ASSIGN), and supporting routines
LAT$RATING.EXE CPU load-balancing routines for LAT
LCK$DEBUG.EXE Lock manager trace routines
LMF$GROUP_TABLE.EXE 4 Data structures for licensed product groups
LOCKING.STB Lock management routines and system services
LOGICAL_NAMES.STB Logical name routines and system services
MESSAGE_ROUTINES.STB System message routines and system services (including $SNDJBC and $GETTIM)
MSCP.EXE Disk MSCP server
MULTIPATH.STB 1 Fibrechannel multipath support routines
NET$CSMACD.EXE CSMA/CD LAN management module
NET$FDDI.EXE FDDI LAN management module
NT_EXTENSION.EXE NT extensions for persona system services
PROCESS_MANAGEMENT.STB 1 Scheduler, report system event, and supporting routines and system services
RECOVERY_UNIT_SERVICES.STB Recovery unit system services
RMS.EXE Global symbols and entry points for RMS
SECURITY.STB 1 Security management routines and system services
SHELL xxK.STB Process shell
SPL$DEBUG.EXE Spinlock trace routines
SSPI.EXE Security Support Provider Interface
SYS$ xxDRIVER.EXE Run-time device drivers
SYS$ACPI.EXE 5 Advanced Configuration and Power Interface routines
SYS$ATMWORKS351.EXE PCI-ATM driver
SYS$CLUSTER.EXE OpenVMS Cluster support routines
SYS$CPU_ROUTINES_ xxxx.EXE 4 Processor-specific data and initialization routines
SYS$EW1000A.EXE Gigabit Ethernet driver
SYS$EW5700.EXE 5 Gigabit Ethernet driver
SYS$GALAXY.STB OpenVMS Galaxy support routines
SYS$HWP nnnn.EXE 5 PCI support routines
SYS$IPC_SERVICES.EXE Interprocess communication for DECdtm and Batch/Print
SYS$IPI nnnn.EXE 5 PCI support routines
SYS$LAN.EXE Common LAN routines
SYS$LAN_ATM.EXE LAN routines for ATM
SYS$LAN_ATM4.EXE LAN routines for ATM (ForeThought)
SYS$LAN_CSMACD.EXE LAN routines for CSMA/CD
SYS$LAN_FDDI.EXE LAN routines for FDDI
SYS$LAN_TR.EXE LAN routines for Token Ring
SYS$MME_SERVICES.STB Media Management Extensions
SYS$NETWORK_SERVICES.EXE DECnet support
SYS$NTA.STB NT affinity routines and services
SYS$ xxxx_SUPPORT.EXE 5 Processor-specific data and initialization routines
SYS$PUBLIC_VECTORS.EXE 2 System service vector base image
SYS$SCS.EXE System Communication Services
SYS$TRANSACTION_SERVICES.EXE DECdtm services
SYS$UTC_SERVICES.EXE Universal Coordinated Time services
SYS$VCC.STB 1, 4 Virtual I/O cache
SYS$VM.STB System pager and swapper, along with their supporting routines, and management system services
SYS$XFCACHE.STB 1 Extented File Cache
SYSDEVICE.STB Mailbox driver and null driver
SYSGETSYI.STB Get System Information system service ($GETSYI)
SYSLDR_DYN.STB Dynamic executive image loader
SYSLICENSE.STB Licensing system service ($LICENSE)
SYSTEM_DEBUG.EXE XDelta and SCD routines
SYSTEM_PRIMITIVES.STB 1 Miscellaneous basic system routines, including those that allocate system memory, maintain system time, create fork processes, and control mutex acquisition
SYSTEM_SYNCHRONIZATION.STB 1 Routines that enforce synchronization
TCPIP$BGDRIVER.STB 3 TCP/IP internet driver
TCPIP$INETACP.STB 3 TCP/IP internet ACP
TCPIP$INETDRIVER.STB 3 TCP/IP internet driver
TCPIP$INTERNET_SERVICES.STB 3 TCP/IP internet execlet
TCPIP$NFS_SERVICES.STB 3 Symbols for the TCP/IP NFS server
TCPIP$PROXY_SERVICES.STB 3 Symbols for the TCP/IP proxy execlet
TCPIP$PWIPACP.STB 3 TCP/IP PWIP ACP
TCPIP$PWIPDRIVER.STB 3 TCP/IP PWIP driver
TCPIP$TNDRIVER.STB 3 TCP/IP TELNET/RLOGIN server driver
TMSCP.EXE Tape MSCP server
VMS_EXTENSION.EXE VMS extensions for persona system services

1Variations of these files also exist, for example, where the file name ends in "_MON." System parameters such as SYSTEM_CHECK determine which image is loaded.
2This file is located in SYS$LIBRARY.
3Only available if TCP/IP has been installed. These are found in SYS$SYSTEM, and are not automatically read in when you issue a READ/EXEC command.
4Alpha only.
5I64 only.

SDA can also read symbols from an image .EXE or .STB produced by the linker. The STB and EXE files only contain universal symbols. The STB file, however, can be forced to have global symbols for the image if you use the SYMBOL_TABLE=GLOBAL option in the linker options file.

A number of ready-built symbol table files ship with OpenVMS. They can be found in the directory SYS$LOADABLE_IMAGES, and all have names of the form xyzDEF.STB. Of these files, SDA automatically reads REQSYSDEF.STB on activation. You can add the symbols in the other files to SDA's symbol table using the READ command. Table 2-4 lists the files that OpenVMS provides in SYS$LOADABLE_IMAGES that define data structure offsets.

The following MACRO program, GLOBALS.MAR, shows how to obtain symbols in addition to those in SYS$BASE_IMAGE.EXE, other executive images listed in Table 4-1, and the symbol table files that are listed in Table 2-4: 


.TITLE GLOBALS 
; n.b. on following lines GLOBAL must be capitalized 
$PHDDEF GLOBAL          ; Process header definitions 
$DDBDEF GLOBAL          ; Device data block 
$UCBDEF GLOBAL          ; Unit control block 
$VCBDEF GLOBAL          ; Volume control block 
$ACBDEF GLOBAL          ; AST control block 
$IRPDEF GLOBAL          ; I/O request packet 
; more can be inserted here 
.END

Use the following command to generate an object module file containing the globals defined in the program: 


$MACRO GLOBALS+SYS$LIBRARY:LIB/LIBRARY /OBJECT=GLOBALS.STB

Examples

#1 

SDA>  READ SDA$READ_DIR:SYSDEF.STB/LOG
%SDA-I-READSYM, 10010 symbols read from SYS$COMMON:[SYSEXE]SYSDEF.STB;1

The READ command causes SDA to add all the global symbols in SDA$READ_DIR:SYSDEF.STB to the SDA symbol table. Such symbols are useful when you are formatting an I/O data structure, such as a unit control block or an I/O request packet.

#2 

SDA> SHOW STACK
Process stacks (on CPU 00)
--------------------------
Current operating stack (KERNEL):
                                 
        00000000.7FF95CD0  FFFFFFFF.80430CE0  SCH$STATE_TO_COM+00040
        00000000.7FF95CD8  00000000.00000000
        00000000.7FF95CE0  FFFFFFFF.81E9CB04  LNM$SEARCH_ONE_C+000E4
        00000000.7FF95CE8  FFFFFFFF.8007A988  PROCESS_MANAGEMENT_NPRO+0E988
   SP =>00000000.7FF95CF0  00000000.00000000
        00000000.7FF95CF8  00000000.006080C1
        00000000.7FF95D00  FFFFFFFF.80501FDC
        00000000.7FF95D08  FFFFFFFF.81A5B720
   .
   .
   .
 
SDA>  READ/IMAGE SYS$LOADABLE_IMAGES:PROCESS_MANAGEMENT/LOG
%SDA-I-READSYM, 767 symbols read from SYS$COMMON:[SYS$LDR]PROCESS_MANAGEMENT.STB;1
SDA>  SHOW STACK
Process stacks (on CPU 00)
--------------------------
Current operating stack (KERNEL):
                                 
        00000000.7FF95CD0  FFFFFFFF.80430CE0  SCH$FIND_NEXT_PROC
        00000000.7FF95CD8  00000000.00000000
        00000000.7FF95CE0  FFFFFFFF.81E9CB04  LNM$SEARCH_ONE_C+000E4
        00000000.7FF95CE8  FFFFFFFF.8007A988  SCH$INTERRUPT+00068
   SP =>00000000.7FF95CF0  00000000.00000000
        00000000.7FF95CF8  00000000.006080C1
        00000000.7FF95D00  FFFFFFFF.80501FDC
        00000000.7FF95D08  FFFFFFFF.81A5B720
   .
   .
   .

The initial SHOW STACK command contains an address that SDA resolves into an offset from the PROCESS_MANAGEMENT executive image. The READ command loads the corresponding symbols into the SDA symbol table such that the reissue of the SHOW STACK command subsequently identifies the same location as an offset within a specific process management routine.

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