HP OpenVMS Systems Documentation

OpenVMS Alpha System Analysis Tools Manual

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

SDA>  READ SDA$READ_DIR:SYSDEF.STB
%SDA-I-READSYM, 10010 symbols read from SYS$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.

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$LOADABLE_IMAGES:PROCESS_MANAGEMENT
%SDA-I-READSYM, 767 symbols read from SYS$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.

Repeats execution of the last command issued. On terminal devices, the KP0 key performs the same function as the REPEAT command with no parameter or qualifier.

Format

REPEAT [count|/UNTIL=condition]

Parameter

count

Number of times the previous command is to be repeated. The default is a single repeat.

Qualifier

/UNTIL=condition

Defines a condition that terminates the REPEAT command. By default, there is no terminating condition.

Description

The REPEAT command is useful for stepping through a linked list of data structures, or for examining a sequence of memory locations. When used with ANALYZE/SYSTEM, it allows the changing state of a system location or data structure to be monitored.

Examples

  1. SDA> SPAWN CREATE SDATEMP.COM
             SEARCH  0:3FFFFFFF   12345678
             SET PROCESS/NEXT
             ^Z
     SDA> SET PROCESS NULL
     SDA> @SDATEMP
     SDA> REPEAT/UNTIL = BADPROC

This example demonstrates how to search the address space of each process in a system or dump a given pattern.

  2. SDA> SHOW CALL_FRAME
     Call Frame Information
     ----------------------
             Stack Frame Procedure Descriptor
     Flags:  Base Register = FP, Jacket, Native
             Procedure Entry: FFFFFFFF.80080CE0           MMG$RETRANGE_C+00180
             Return address on stack = FFFFFFFF.8004CF30  EXCEPTION_NPRO+00F30

    Registers saved on stack
    ------------------------
    7FF95E80 FFFFFFFF.FFFFFFFD  Saved R2
    7FF95E88 FFFFFFFF.8042DBC0  Saved R3      EXCEPTION_NPRW+03DC0
    7FF95E90 FFFFFFFF.80537240  Saved R4
    7FF95E98 00000000.00000000  Saved R5
    7FF95EA0 FFFFFFFF.80030960  Saved R6      MMG$IMGRESET_C+00200
    7FF95EA8 00000000.7FF95EC0  Saved R7
    7FF95EB0 FFFFFFFF.80420E68  Saved R13     MMG$ULKGBLWSL E
    7FF95EB8 00000000.7FF95F70  Saved R29
    .
    .
    .
    SDA> SHOW CALL_FRAME/NEXT_FP

    Call Frame Information
    ----------------------
            Stack Frame Procedure Descriptor
    Flags:  Base Register = FP, Jacket, Native
            Procedure Entry: FFFFFFFF.80F018D0              IMAGE_MANAGEMENT_PRO+078D0
            Return address on stack = FFFFFFFF.8004CF30     EXCEPTION_NPRO+00F30


    Registers saved on stack
    ------------------------
    7FF95F90 FFFFFFFF.FFFFFFFB  Saved R2
    7FF95F98 FFFFFFFF.8042DBC0  Saved R3      EXCEPTION_ NPRW+03DC0
    7FF95FA0 00000000.00000000  Saved R5
    7FF95FA8 00000000.7FF95FC0  Saved R7
    7FF95FB0 FFFFFFFF.80EF8D20  Saved R13     ERL$DEVINF O+00C20
    7FF95FB8 00000000.7FFA0450  Saved R29
    .
    .
    .
    SDA> REPEAT
    Call Frame Information
    ----------------------
            Stack Frame Procedure Descriptor
    Flags:  Base Register = FP, Jacket, Native
            Procedure Entry: FFFFFFFF.80F016A0              IMAGE_MANAGEMENT_PRO+076A0
            Return address on stack = 00000000.7FF2451C


            Registers saved on stack
            ------------------------
     7FFA0470 00000000.7FEEA890  Saved R13
     7FFA0478 00000000.7FFA0480  Saved R29
     .
     .
     .

The first SHOW CALL_FRAME displays the call frame indicated by the current FP value. Because the /NEXT_FP qualifier to the instruction displays the call frame indicated by the saved FP in the current call frame, you can use the REPEAT command to repeat the SHOW CALL_FRAME/NEXT_FP command and follow a chain of call frames.

Scans a range of memory locations for all occurrences of a specified value.

Format

SEARCH [/qualifier] range [=] expression

Parameters

range

Location in memory to be searched. A location can be represented by any valid SDA expression. To search a range of locations, use the following syntax:

m:n	Range of locations to be searched, from m to n
m;n	Range of locations to be searched, starting at m and continuing for n bytes

expression

Value for which SDA is to search. SDA evaluates the expression and searches the specified range of memory for the resulting value. For a description of SDA expressions, see Section 2.6.2.

If you do not use an equals sign to separate range and expression, then you must insert a space between them.

Qualifiers

/LENGTH={QUADWORD|LONGWORD|WORD |BYTE }

Specifies the size of the expression value that the SEARCH command uses for matching. If you do not specify the /LENGTH qualifier, the SEARCH command uses a longword length by default.

/MASK=n

Allows the SEARCH command finer qranularity in its matches. It compares only the given bits of a byte, word, longword, or quadword. To compare bits when matching, you set the bits in the mask; to ignore bits when matching, you clear the bits in the mask.

/PHYSICAL

Specifies that the addresses used to define the range of locations to be searched are physical addresses.

/STEPS={QUADWORD|LONGWORD|WORD |BYTE|value }

Specifies the step factor of the search through the specified memory range. After the SEARCH command has performed the comparison between the value of expression and memory location, it adds the specified step factor to the address of the memory location. The resulting location is the next location to undergo the comparison. If you do not specify the /STEPS qualifier, the SEARCH command uses a step factor of a longword.

Description

SEARCH displays each location as each value is found. If you press Ctrl/T while using the SEARCH command, the system displays how far the search has progressed. The progress display is always output to the terminal even if a SET OUTPUT <file> command has previously been entered.

Examples

SDA> SEARCH GB81F0;500 B41B0000
Searching from FFFFFFFF.800B81F0 to FFFFFFFF.800B86EF in LONGWORD steps for B41B0000...
Match at FFFFFFFF.800B86E4    B41B0000
      

This SEARCH command finds the value B41B0000 in the longword at FFFFFFFF.800B86E4.

SDA> SEARCH 80000000;200/STEPS=BYTE 82
Searching from FFFFFFFF.80000000 to FFFFFFFF.800001FF in BYTE steps for 00000082...
Match at FFFFFFFF.8000012C    00000082
      

This SEARCH command finds the value 00000082 in the longword at FFFFFFFF.8000012C.

SDA> SEARCH/LENGTH=WORD 80000000;100 10
Match at FFFFFFFF.80000030    0010
Match at FFFFFFFF.80000040    0010
Match at FFFFFFFF.80000090    0010
Match at FFFFFFFF.800000A0    0010
Match at FFFFFFFF.800000C0    0010
5 matches found
      

This SEARCH command finds the value 0010 in the words at FFFFFFFF.80000030, FFFFFFFF.80000040, FFFFFFFF.80000090, FFFFFFFF.800000A0, FFFFFFFF.800000C0.

SDA> SEARCH/MASK=FF000000 80000000;40 20000000
Searching from FFFFFFFF.80000000 to FFFFFFFF.8000003F in LONGWORD steps for 20000000...
(Using search mask of FF000000)
Match at FFFFFFFF.80000000    201F0104
Match at FFFFFFFF.80000010    201F0001
2 matches found
      

This SEARCH command finds the value 20 in the upper byte of the longwords at FFFFFFFF.80000000 and FFFFFFFF.80000010, regardless of the contents of the lower 3 bytes.

When analyzing a system dump, selects a processor to become the current CPU for SDA. (You cannot use this command when analyzing the running system.)

Format

SET CPU cpu-id

Parameter

cpu-id

Numeric value from 00₁₆ to 1F₁₆ indicating the identity of the processor to be made the current CPU. If you specify a value outside this range or a cpu-id of a processor that was not active at the time of the system failure, SDA displays the following message:

%SDA-E-CPUNOTVLD, CPU not booted or CPU number out of range

Qualifiers

None.

Description

When you invoke SDA to examine a system dump, the current CPU context for SDA defaults to that of the processor that caused the system to fail. When analyzing a system failure from a multiprocessing system, you may find it useful to examine the context of another processor in the configuration.

The SET CPU command changes the current CPU context for SDA to that of the processor indicated by cpu-id. The CPU specified by this command becomes the current CPU for SDA until you either exit from SDA or change the CPU context for SDA by issuing one of the following commands:

SET CPU cpu-id
SHOW CPU cpu-id
SHOW CRASH
SHOW MACHINE_CHECK cpu-id

The following commands also change the CPU context for SDA if the process-name, pcb-address, or index number (nn) refers to a current process:

SET PROCESS process-name
SET PROCESS/ADDRESS=pcb-address
SET PROCESS/INDEX=nn
SHOW PROCESS process-name
SHOW PROCESS/ADDRESS=pcb-address
SHOW PROCESS/INDEX=nn

Changing CPU context can cause an implicit change in process context under the following circumstances:

• If there is a current process on the CPU made current, SDA changes its process context to that of that CPU's current process.
• If there is no current process on the CPU made current, the SDA process context is undefined and no process-specific information is available until you set the SDA process context to that of a specific process.

See Section 2.5 for further discussion of the way in which SDA maintains its context information.

Enables or disables the automatic clearing of the screen before each new page of SDA output.

Format

SET ERASE_SCREEN {ON|OFF}

Parameters

ON

Enables the screen to be erased before SDA outputs a new heading. This setting is the default.

OFF

Disables the erasing of the screen.

Qualifiers

None.

Description

SDA's usual behavior is to erase the screen and then show the data. By setting the OFF parameter, the clear screen action is replaced by a blank line. This action does not affect what is written to a file when the SET LOG or SET OUTPUT commands are used.

Examples

SDA>  SET ERASE_SCREEN ON
      

The clear screen action is now enabled.

SDA> SET ERASE_SCREEN OFF
      

The clear screen action is disabled.

Sets the default size and access method of address data used when SDA evaluates an expression that includes the @ unary operator.

Format

SET FETCH [{QUADWORD|LONGWORD|WORD|BYTE}][,][{PHYSICAL|VIRTUAL}]

Parameters

QUADWORD

Sets the default size to 8 bytes.

LONGWORD

Sets the default size to 4 bytes.

WORD

Sets the default size to 2 bytes.

BYTE

Sets the default size to 1 byte.

PHYSICAL

Sets the default access method to physical addresses.

VIRTUAL

Sets the default access method to virtual addresses.

You can specify only one parameter out of each group. If you are changing both size and access method, separate the two parameters by spaces or a comma. Include a comma only if you are specifying a parameter from both groups. See examples 5 and 6.

Qualifiers

None.

Description

Sets the default size and/or default access method of address data used by the @ unary operator in commands such as EXAMINE and EVALUATE. SDA uses the current default size unless it is overridden by the ^Q, ^L, ^W, or ^B qualifier on the @ unary operator in an expression. SDA uses the current default access method unless it is overridden by the ^P or ^V qualifier on the @ unary operator in an expression.

Examples

SDA>  EXAMINE MMG$GQ_SHARED_VA_PTES
MMG$GQ_SHARED_VA_PTES:  FFFFFFFD.FF7FE000   ".`a....."
      

This example shows the location's contents of a 64-bit virtual address.

SDA> SET FETCH LONG
SDA> EXAMINE @MMG$GQ_SHARED_VA_PTES
%SDA-E-NOTINPHYS, FFFFFFFF.FF7FE000 : virtual data not in physical memory
      

This example shows a failure because the SET FETCH LONG causes SDA to assume that it should take the lower 32 bits of the location's contents as a longword value, sign-extend them, and use that value as an address.

SDA> EXAMINE @^QMMG$GQ_SHARED_VA_PTES
FFFFFFFD.FF7FE000:  000001D0.40001119   "...@..."
      

This example shows the correct results by overriding the SET FETCH LONG with the ^Q qualifier on the @ operator. SDA takes the full 64 bits of the location's contents and uses that value as an address.

SDA> SET FETCH QUAD
SDA> EXAMINE @MMG$GQ_SHARED_VA_PTES
FFFFFFFD.FF7FE000:  000001D0.40001119   "...@..."
      

This example shows the correct results by changing the default fetch size to a quadword.

SDA> SET FETCH PHYSICAL
SDA> EXAMINE /PHYSICAL @0
      

This command uses the contents of the physical location 0 as the physical address of the location to be examined.

SDA> SET FETCH QUADWORD, PHYSICAL
      

This command sets the default fetch size and default access method at the same time.

Initiates or discontinues the recording of an SDA session in a text file.

Format

SET [NO]LOG filespec

Parameter

filespec

Name of the file in which you want SDA to log your commands and their output. The default filespec is SYS$DISK:[default_dir]filename.LOG, where SYS$DISK and [default-dir] represent the disk and directory specified in your last DCL command SET DEFAULT. You must specify a file name.

Qualifiers

None.

Description

The SET LOG command echoes the commands and output of an SDA session to a log file. The SET NOLOG command terminates this behavior.

The following differences exist between the SET LOG command and the SET OUTPUT command:

• When logging is in effect, your commands and their results are still displayed on your terminal. The SET OUTPUT command causes the displays to be redirected to the output file and they no longer appear on the screen.
• If an SDA command requires that you press Return to produce successive screens of display, the log file produced by SET LOG will record only those screens that are actually displayed. SET OUTPUT, however, sends the entire output of any SDA commands to its listing file.
• The SET LOG command produces a log file with a default file type of .LOG; the SET OUTPUT command produces a listing file whose default file type is .LIS.
• The SET OUTPUT command can generate a table of contents, each item of which refers to a display written to its listing file. SET OUTPUT also produces running heads for each page of output. The SET LOG command does not produce these items in its log file.

If you use the SET OUTPUT command to redirect output to a listing file, a SET LOG command to direct the same output to a log file is ineffective until output is restored to the terminal.