OpenVMS Alpha System Analysis Tools Manual

Document revision date: 19 July 1999

OpenVMS Alpha System Analysis Tools Manual

Contents

Index

The EXAMINE/PTE command displays and formats the level 1 page table entry at FFFFFFFF.FF7FC000.

EXIT

Exits from an SDA display or exits from the SDA utility.

Format

EXIT

Parameters

None.

Qualifiers

None.

Description

If SDA is displaying information on a video display terminal---and if that information extends beyond one screen---SDA displays a screen overflow prompt at the bottom of the screen:
Press RETURN for more. SDA>
If you want to discontinue the current display at this point, enter the EXIT command. If you want SDA to execute another command, enter that command. SDA discontinues the display as if you entered EXIT, and then executes the command you entered.
When the SDA> prompt is not immediately preceded by the screen overflow prompt, entering EXIT causes your process to cease executing the SDA utility. When issued within a command procedure (either the SDA initialization file or a command procedure invoked with the execute command (@)), EXIT causes SDA to terminate execution of the procedure and return to the SDA prompt.

FORMAT

Displays a formatted list of the contents of a block of memory.

Format

FORMAT [/TYPE=block-type] location [/PHYSICAL]

Parameter

location
Location of the beginning of the data block. The location can be given as any valid SDA expression.

Qualifiers

/TYPE=block-type
Forces SDA to characterize and format a data block at location as the specified type of data structure. The /TYPE qualifier thus overrides the default behavior of the FORMAT command in determining the type of a data block, as described in the Description section. The block-type can be the symbolic prefix of any data structure defined by the operating system.
/PHYSICAL
Specifies that the location given is a physical address.

Description

The FORMAT command performs the following actions:

Characterizes a range of locations as a system data block
Assigns, if possible, a symbol to each item of data within the block
Displays all the data within the block

Most OpenVMS Alpha control blocks include a byte that indicates the block type, and associates the block with a set of symbols that have a common prefix. Each symbol's name describes a field within the block, and the value of the symbol represents the offset of the field within the block.
If the block-type byte contains a valid block type (and/or subtype), SDA retrieves the symbols associated with that type of block (see $DYNDEF) and uses their values to format the block.
For a given block type, all associated symbols have the form
<block type>$<type>_<name>
where type is one of the following:
B Byte W Word L Longword Q Quadword A Address C Constant G Global Longword P Pointer R Structure (variable size) T Counted ASCII string (up to 31 characters)
If SDA cannot find the symbols associated with the block type specified in the block-type byte or by the /TYPE qualifier, it issues this message:
%SDA-E-NOSYMBOLS, no <block type> symbols found to format this block
If you receive this message, you may want to read additional symbols into the SDA symbol table and retry the FORMAT command. Many symbols that define OpenVMS Alpha data structures are contained within SDA$READ_DIR:SYSDEF.STB. Thus, you would issue the following command:
SDA> READ SDA$READ_DIR:SYSDEF.STB
If SDA issues the same message again, try reading additional symbols. Table 2-4 lists additional modules provided by the OpenVMS operating system. Alternatively, you can create your own object modules with the MACRO-32 Compiler for OpenVMS Alpha. See the READ command description for instructions on creating such an object module.
Certain OpenVMS Alpha data structures do not contain a block type at offset 0A₁₆. If this byte contains information other than a block type---or the byte does not contain a valid block type---SDA either formats the block in a totally inappropriate way, based on the contents of 0A₁₆ and 0B₁₆, or displays this message:
%SDA-E-INVBLKTYP, invalid block type in specified block
To format such a block, you must reissue the FORMAT command, using the /TYPE qualifier to designate a block-type.
The FORMAT command produces a 3-column display:

The first column shows the virtual address of each item within the block.
The second column lists each symbolic name associated with a location within the block.
The third column shows the contents of each item in hexadecimal format.

Example


SDA>READ SDA$READ_DIR:SYSDEF.STB %SDA-I-READSYM, 913 symbols read from SYS$COMMON:[SYS$LDR]SYSDEF.STB SDA>FORMAT G41F818 FFFFFFFF.8041F818 UCB$L_FQFL 8041F818 UCB UCB$L_MB_MSGQFL UCB$L_RQFL UCB$W_MB_SEED UCB$W_UNIT_SEED FFFFFFFF.8041F81C UCB$L_FQBL 8041F818 UCB UCB$L_MB_MSGQBL UCB$L_RQBL FFFFFFFF.8041F820 UCB$W_SIZE 0110 FFFFFFFF.8041F822 UCB$B_TYPE 10 FFFFFFFF.8041F823 UCB$B_FLCK 2C FFFFFFFF.8041F824 UCB$L_ASTQFL 00000000 UCB$L_FPC UCB$L_MB_W_AST UCB$T_PARTNER . . .

SDA>READ SDA$READ_DIR:SYSDEF.STB
%SDA-I-READSYM, 913 symbols read from SYS$COMMON:[SYS$LDR]SYSDEF.STB
SDA>FORMAT G41F818
FFFFFFFF.8041F818   UCB$L_FQFL                      8041F818        UCB
                    UCB$L_MB_MSGQFL                 
                    UCB$L_RQFL                      
                    UCB$W_MB_SEED                   
                    UCB$W_UNIT_SEED                 
FFFFFFFF.8041F81C   UCB$L_FQBL                      8041F818        UCB
                    UCB$L_MB_MSGQBL                 
                    UCB$L_RQBL                      
FFFFFFFF.8041F820   UCB$W_SIZE                          0110         
FFFFFFFF.8041F822   UCB$B_TYPE                        10     
FFFFFFFF.8041F823   UCB$B_FLCK                      2C       
FFFFFFFF.8041F824   UCB$L_ASTQFL                    00000000         
                    UCB$L_FPC                       
                    UCB$L_MB_W_AST                  
                    UCB$T_PARTNER                   
   .
   .
   .

The READ command loads into SDA's symbol table the symbols from SDA$READ_DIR:SYSDEF.STB. The FORMAT command displays the data structure that begins at G41F818₁₆, a unit control block (UCB). If a field has more than one symbolic name, all such names are displayed. Thus, the field that starts at 8041F824₁₆ has four designations: UCB$L_ASTQFL, UCB$L_FPC, UCB$L_MB_W_AST, and UCB$T_PARTNER.
The contents of each field appear to the right of the symbolic name of the field. Thus, the contents of UCB$L_FQBL are 8041F818₁₆.

HELP

Displays information about the SDA utility, its operation, and the format of its commands.

Format

HELP [command-name]

Parameter

command-name
Command for which you need information.
You can also specify the following keywords in place of command-name:

Keyword Function

CPU_CONTEXT Describes the concept of CPU context as it governs the behavior of SDA.

EXECUTE_COMMAND Describes the use of @ file to execute SDA commands contained in a file.

EXPRESSIONS Prints a description of SDA expressions.

INITIALIZATION Describes the circumstances under which SDA executes an initialization file when first invoked.

OPERATION Describes how to operate SDA at your terminal and by means of the site-specific startup procedure.

PROCESS_CONTEXT Describes the concept of process context as it governs the behavior of SDA.

SYMBOLS Describes the symbols used by SDA.

Keyword	Function
CPU_CONTEXT	Describes the concept of CPU context as it governs the behavior of SDA.
EXECUTE_COMMAND	Describes the use of @ file to execute SDA commands contained in a file.
EXPRESSIONS	Prints a description of SDA expressions.
INITIALIZATION	Describes the circumstances under which SDA executes an initialization file when first invoked.
OPERATION	Describes how to operate SDA at your terminal and by means of the site-specific startup procedure.
PROCESS_CONTEXT	Describes the concept of process context as it governs the behavior of SDA.
SYMBOLS	Describes the symbols used by SDA.

Qualifiers

None.

Description

The HELP command displays brief descriptions of SDA commands and concepts on the terminal screen (or sends these descriptions to the file designated in a SET OUTPUT command). You can request additional information by specifying the name of a topic in response to the Topic? prompt.
If you do not specify a parameter in the HELP command, it lists those commands and topics for which you can request help, as follows:
Information available: ATTACH CLUE COPY CPU_Context DEFINE EVALUATE EXAMINE Execute_Command EXIT Expressions FORMAT HELP Initialization MAP Operation Process_Context READ REPEAT SEARCH SET SHOW SPAWN Symbols VALIDATE Topic?

MAP

Transforms an address into an offset in a particular image.

Format

MAP address

Parameter

address
Address to be identified.

Qualifiers

None.

Description

The MAP command identifies the image name and offset corresponding to an address. With this information, you can examine the image map to locate the source module and program section offset corresponding to an address. MAP searches for the specified address in executive images first. It then checks activated images in process space to include those images installed using the /RESIDENT qualifier of the Install utility. Finally, it checks all image-resident sections in system space.
If the address cannot be found, MAP displays the following message:
%SDA-E-NOTINIMAGE, Address not within a system/installed image

Examples

#1
SDA> MAP G90308 Image Base End Image Offset SYS$VM Nonpaged read only 80090000 800ABA00 00000308

Examining the image map identified by this MAP command (SYS$VM.MAP) shows that image offset 308 falls within psect EXEC$HI_USE_PAGEABLE_CODE because the psect goes from offset 0 to offset 45D3:

Psect Name Module Name Base End Length Align ---------- ----------- ---- --- ------ ----- $CODE$ 00000000 00000000 00000000 ( 0.) QUAD 3... BUGCHECK_CODES 00000000 00000000 00000000 ( 0.) QUAD 3 $GLOBAL$ 00000000 00000000 00000000 ( 0.) QUAD 3... BUGCHECK_CODES 00000000 00000000 00000000 ( 0.) QUAD 3 $LINK$ 00000000 00000000 00000000 ( 0.) QUAD 3... BUGCHECK_CODES 00000000 00000000 00000000 ( 0.) QUAD 3 $OWN$ 00000000 00000000 00000000 ( 0.) QUAD 3... BUGCHECK_CODES 00000000 00000000 00000000 ( 0.) QUAD 3 $PLIT$ 00000000 00000000 00000000 ( 0.) QUAD 3... BUGCHECK_CODES 00000000 00000000 00000000 ( 0.) QUAD 3 . LITERAL . 00000000 00000000 00000000 ( 0.) QUAD 3... BUGCHECK_CODES 00000000 00000000 00000000 ( 0.) QUAD 3 . BLANK . 00000000 00000000 00000000 ( 0.) OCTA 4... SYS$DOINIT 00000000 00000000 00000000 ( 0.) OCTA 4 EXECUTE_FAULT 00000000 00000000 00000000 ( 0.) OCTA 4 GSD_ROUTINES 00000000 00000000 00000000 ( 0.) OCTA 4 IOLOCK 00000000 00000000 00000000 ( 0.) OCTA 4 . . . EXEC$HI_USE_PAGEABLE_CODE 00000000 000045D3 000045D4 ( 17876.) 2 ** 5... SYSCREDEL 00000000 0000149B 0000149C ( 5276.) 2 ** 5 SYSCRMPSC 000014A0 000045D3 00003134 ( 12596.) 2 ** 5 EXEC$NONPAGED_CODE 000045E0 0001B8B3 000172D4 ( 94932.) 2 ** 5... EXECUTE_FAULT 000045E0 0000483B 0000025C ( 604.) 2 ** 5 IOLOCK 00004840 000052E7 00000AA8 ( 2728.) 2 ** 5 LOCK_SYSTEM_PAGES . . .

Specifically, image offset 308 is located within source module SYSCREDEL. Therefore, to locate the corresponding code, you would look in SYSCREDEL for offset 308 in psect EXEC$HI_USE_PAGEABLE_CODE.

#2
SDA> MAP G550000 Image Base End Image Offset SYS$DKDRIVER 80548000 80558000 00008000

In this example, the MAP command identifies the address as an offset into an executive image that is not sliced. The base and end addresses are the boundaries of the image.

#3
SDA> MAP G550034 Image Base End Image Offset SYS$DUDRIVER Nonpaged read/write 80550000 80551400 00008034

In this example, the MAP command identifies the address as an offset into an executive image that is sliced. The base and end addresses are the boundaries of the image section that contains the address of interest.

#4
SDA> MAP GF0040 Image Resident Section Base End Image Offset MAILSHR 800F0000 80119000 00000040

The MAP command identifies the address as an offset into an image-resident section residing in system space.

#5
SDA> MAP 12000 Activated Image Base End Image Offset MAIL 00010000 000809FF 00002000

The MAP command identifies the address as an offset into an activated image residing in process-private space.

#6
SDA> MAP B2340 Compressed Data Section Base End Image Offset LIBRTL 000B2000 000B6400 00080340

The MAP command identifies the address as being within a compressed data section. When an image is installed with the Install utility using the /RESIDENT qualifier, the code sections are mapped in system space. The data sections are compressed into process-private space to reduce null pages or holes in the address space left by the absence of the code section. The SHOW PROCESS/IMAGE display shows how the data has been compressed; the MAP command searches this information to map an address in a compressed data section to an offset in an image.

#7
SDA> MAP 7FC06000 Shareable Address Data Section Base End Image Offset LIBRTL 7FC06000 7FC16800 00090000

The MAP command identifies the address as an offset into a shareable address data section residing in P1 space.

#8
SDA> MAP 7FC26000 Read-Write Data Section Base End Image Offset LIBRTL 7FC26000 7FC27000 000B0000

The MAP command identifies the address as an offset into a read-write data section residing in P1 space.

#9
SDA> MAP 7FC36000 Shareable Read-Only Data Section Base End Image Offset LIBRTL 7FC36000 7FC3F600 000C0000

The MAP command identifies the address as an offset into a shareable read-only data section residing in P1 space.

#10
SDA> MAP 7FC56000 Demand Zero Data Section Base End Image Offset LIBRTL 7FC56000 7FC57000 000E0000

The MAP command identifies the address as an offset into a demand zero data section residing in P1 space.

MODIFY DUMP

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

Format

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

Parameter

value
The new value deposited in the specified location in the dump file.

Qualifiers

/BLOCK=n
Block number to be modified. Required unless the /NEXT qualifier is given.
/OFFSET=n
Byte offset within block to be modified. Required unless the /NEXT qualifier is given.
/CONFIRM=n
Checks existing contents of location to be modified.
/NEXT
Indicates that the byte(s) immediately following the location altered by the previous MODIFY DUMP command is/are to be modified. Used instead of the /BLOCK=n and /OFFSET=n qualifiers.
/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. The MODIFY DUMP command corrects the problem that prevents normal analysis of a dump file. The MODIFY DUMP command can only be used when SDA has been invoked with the ANALYZE/CRASH_DUMP/ OVERRIDE command.

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

Note that if the block being modified is part of the dump header, the error log buffers, or the compression map, the changes made are not seen when the appropriate SHOW DUMP command is issued, 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

Example


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

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


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

This example shows that the actual word value of 00FF at offset 100 in block 00000010 does not match given value of 00EE. The following message is displayed:
%SDA-E-NOMATCH, expected value does not match value in dump; dump not updated


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
The directory-spec is the 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.

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 image has a symbols vector (is a shareable image), and a symbols vector was not specified with the /SYMVA or /IMAGE qualifier.
The image is sliced, and slicing information was not provided with the /IMAGE qualifier.
The shareable or executive image is not loaded at the same address it was linked at, and the relocation information was not provided with either the /IMAGE or /RELOCATE qualifier.

The use of /FORCE [/SYMVA=addr][/RELOCATE=addr] file spec 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 and global symbols, unless SYMBOL_TABLE=GLOBAL is in the linker options file, in which case the .STB file contains global symbols only.
/LOG
/NOLOG
The /LOG qualifier causes SDA to output the %SDA-I-READSYM message for each symbol table file it reads. This is the default. The /LOG qualifier can be specified with any other combination of parameter and qualifier.
The /NOLOG qualifier suppresses the output of the %SDA-I-READSYM messages. The /NOLOG qualifier can be specified with any other combination of parameter and qualifier.
/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).

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OpenVMS Alpha System Analysis Tools Manual

EXIT

Format

EXIT

Parameters

Qualifiers

Description

FORMAT

Format

FORMAT [/TYPE=block-type] location [/PHYSICAL]

Parameter

location

Qualifiers

/TYPE=block-type

/PHYSICAL

Description

Example

HELP

Format

HELP [command-name]

Parameter

command-name

Qualifiers

Description

MAP

Format

MAP address

Parameter

address

Qualifiers

Description

Examples

MODIFY DUMP

Format

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

Parameter

value

Qualifiers

/BLOCK=n

/OFFSET=n

/CONFIRM=n

/NEXT

/BYTE

/WORD

/LONGWORD

/QUADWORD

Description

Example

READ

Format

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

Parameters

directory-spec

filespec

Qualifiers

/EXECUTIVE directory-spec

/FORCE filespec

/IMAGE filespec

/LOG /NOLOG

/RELOCATE=expression

/SYMVA=expression

Description

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

/LOG
/NOLOG