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HP OpenVMS Systems Documentation |
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OpenVMS Alpha System Analysis Tools Manual
EVALUATE
Computes and displays the value of the specified expression in both hexadecimal and decimal. Alternative evaluations of the expression are available with the use of the qualifiers defined for this command. FormatEVALUATE [{/CONDITION_VALUE|/PS|/PTE Parameter
Qualifiers
DescriptionIf you do not specify a qualifier, the EVALUATE command interprets and displays the expression as hexadecimal and decimal values. In addition, if the expression is equal to the value of a symbol in the SDA symbol table, that symbol is displayed. If no symbol with this value is known, the next lower valued symbol is displayed with an appropriate offset unless the offset is extremely large. (See Section 2.6.2.4 for a description of how SDA displays symbols and offsets.) The DEFINE command adds symbols to the SDA symbol table but does not display the results of the computation. EVALUATE displays the result of the computation but does not add symbols to the SDA symbol table.
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| #1 |
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SDA> EVALUATE -1
Hex = FFFFFFFF.FFFFFFFF Decimal = -1 I
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The EVALUATE command evaluates a numeric expression, displays the value of that expression in hexadecimal and decimal notation, and displays a symbol that has been defined to have an equivalent value.
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SDA> EVALUATE 1
Hex = 00000000.00000001 Decimal = 1 CHF$M_CALEXT_CANCEL
CHF$M_FPREGS_VALID
CHF$V_CALEXT_LAST
IRP$M_BUFIO
IRP$M_CLN_READY
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(remaining symbols suppressed by default)
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The EVALUATE command evaluates a numeric expression and displays the value of that expression in hexadecimal and decimal notation. This example also shows the symbols that have the displayed value. A maximum of five symbols are displayed by default.
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SDA> DEFINE TEN = A
SDA> EVALUATE TEN
Hex = 00000000.0000000A Decimal = 10 IRP$B_TYPE
IRP$S_FMOD
IRP$V_MBXIO
TEN
UCB$B_TYPE
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(remaining symbols suppressed by default)
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This example shows the definition of a symbol named TEN. The EVALUATE command then shows the value of the symbol.
Note that A, the value assigned to the symbol by the DEFINE command, could be a symbol. When SDA evaluates a string that can be either a symbol or a hexadecimal numeral, it first searches its symbol table for a definition of the symbol. If SDA finds no definition for the string, it evaluates the string as a hexadecimal number.
| #4 |
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SDA> EVALUATE (((TEN * 6) + (-1/4)) + 6)
Hex = 00000000.00000042 Decimal = 66
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This example shows how SDA evaluates an expression of several terms, including symbols and rational fractions. SDA evaluates the symbol, substitutes its value in the expression, and then evaluates the expression. The fraction -1/4 is truncated to 0.
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SDA> EVALUATE/CONDITION 80000018
%SYSTEM-W-EXQUOTA, exceeded quota
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This example shows the output of an EVALUATE/CONDITION command.
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SDA> EVALUATE/PS 0B03
MBZ SPAL MBZ IPL VMM MBZ CURMOD INT PRVMOD
0 00 00000000000 0B 0 0 KERN 0 USER
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SDA interprets the entered value 0B03 as though it were a processor status (PS) and displays the resulting field values.
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SDA> EVALUATE/PTE 0BCDFFEE
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The EVALUATE/PTE command displays the expression 0BCDFFEE as a page table entry (PTE) and labels the fields. It also describes the status of the page.
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SDA> EVALUATE/TIME 009A9A4C.843DBA9F
10-OCT-1996 15:59:44.02
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This example shows the use of the EVALUATE/TIME command.
Displays either the contents of a location or range of locations in physical memory, or the contents of a register. Use location parameters to display specific locations or use qualifiers to display the entire process and system regions of memory.
EXAMINE [/qualifier[,...]] [location]
location
Location in memory to be examined. A location can be represented by any valid SDA expression. (See Section 2.6.2 for additional information about expressions.) To examine a range of locations, use the following syntax:
m:n Range of locations to be examined, from m to n m;n Range of locations to be examined, starting at m and continuing for n bytes The default location that SDA uses is initially 0 in the program region (P0) of the process that was executing at the time the system failed (if you are examining a crash dump) or your process (if you are examining the running system). Subsequent uses of the EXAMINE command with no parameter specified increase the last address examined by eight. Use of the /INSTRUCTION qualifier increases the default address by four. To examine memory locations of other processes, you must use the SET PROCESS command.
/ALL
Examines all the locations in the program, and control regions and system space, displaying the contents of memory in hexadecimal longwords and ASCII characters. Do not specify parameters when you use this qualifier./CONDITION_VALUE
Examines the specified longword, displaying the message that the $GETMSG system service obtains for the value in the longword./INSTRUCTION
Translates the specified range of memory locations into assembly instruction format. Each symbol in the EXAMINE expression that is defined as a procedure descriptor is replaced with the code entry point address of that procedure, unless you also specify the /NOPD qualifier./NOPD
Can be used with the /INSTRUCTION qualifier to override treating symbols as procedure descriptors. You can place the qualifier immediately after the /INSTRUCTION qualifier, or following a symbol name.For more details on using the /NOPD qualifier, see the description for the /PD qualifier.
/NOSUPPRESS
Inhibits the suppression of zeros when displaying memory with one of the following qualifiers: /ALL, /P0, /P1, /SYSTEM, or when a range is specified./P0
Displays the entire program region for the default process. Do not specify parameters when you use this qualifier./P1
Displays the entire control region for the default process. Do not specify parameters when you use this qualifier./PD
Causes the EXAMINE command to treat the location specified in the EXAMINE command as a procedure descriptor (PD). PD can also be used to qualify symbols.You can use the /PD and /NOPD qualifiers with the /INSTRUCTION qualifier to override treating symbols as procedure descriptors. Placing the qualifier right after a symbol will override how the symbol is treated. /PD will force it to be a procedure descriptor, and /NOPD will force it to not be a procedure descriptor.
Only the /PD qualifier can be placed right after the /INSTRUCTION qualifier. It treats the calculated value as a procedure descriptor.
In the following examples, TEST_ROUTINE is a PD symbol. Its value is 500 and the code address in this procedure descriptor is 1000. The first example displays intructions starting at 520.
EXAMINE/INSTRUCTION TEST_ROUTINE/NOPD+20The next example fetches code address from TEST_ROUTINE PD, adds 20 and displays instructions at that address. In other words, it displays code starting at location 1020.
EXAMINE/INSTRUCTION TEST_ROUTINE+20The final example treates the address TEST_ROUTINE+20 as a procedure descriptor, so it fetches the code address out of a procedure descriptor at address 520. It then uses that address to display instructions.
EXAMINE/INSTRUCTION/PD TEST_ROUTINE/NOPD+20/PHYSICAL
Examines physical addresses. You cannot use the /PHYSICAL qualifier in combination with the /P0, /P1, or /SYSTEM qualifiers./PS
Examines the specified quadword, displaying its contents in the format of a processor status. This qualifier must precede any parameters used in the command line./PTE
Interprets and displays the specified quadword as a page table entry (PTE). The display separates individual fields of the PTE and provides an overall description of the PTE's type./SYSTEM
Displays portions of the writable system region. Do not specify parameters when you use this qualifier./TIME
Examines the specified quadword, displaying its contents in the format of a system-date-and-time quadword.
The following sections describe how to use the EXAMINE command.When you use the EXAMINE command to look at a location, SDA displays the location in symbolic notation (symbolic name plus offset), if possible, and its contents in hexadecimal and ASCII formats:
SDA> EXAMINE G6605C0 806605C0: 64646464.64646464 "dddddddd"If the ASCII character that corresponds to the value contained in a byte is not printable, SDA displays a period (.). If the specified location does not exist in memory, SDA displays this message:
%SDA-E-NOTINPHYS, address : virtual data not in physical memoryTo examine a range of locations, you can designate starting and ending locations separated by a colon. For example:
Alternatively, you can specify a location and a length, in bytes, separated by a semicolon. For example:
SDA> EXAMINE G40:G200
SDA> EXAMINE G400;16When used to display the contents of a range of locations, the EXAMINE command displays six or ten columns of information. Ten columns are used if the terminal width is 132 or greater, or if a SET OUTPUT has been entered; six columns are used otherwise. An explanation of the columns is as follows:
- Each of the first four or eight columns represents a longword of memory, the contents of which are displayed in hexadecimal format.
- The fifth or ninth column lists the ASCII value of each byte in each longword displayed in the previous four or eight columns.
- The sixth or tenth column contains the address of the first, or rightmost, longword in each line. This address is also the address of the first, or leftmost, character in the ASCII representation of the longwords. Thus, you read the hexadecimal dump display from right to left, and the ASCII display from left to right.
If a series of virtual addresses does not exist in physical memory, SDA displays a message specifying the range of addresses that were not translated.
If a range of virtual locations contains only zeros, SDA displays this message:
Zeros suppressed from 'loc1' to 'loc2'You can translate the contents of memory locations into instruction format by using the /INSTRUCTION qualifier. This qualifier causes SDA to display the location in symbolic notation (if possible) and its contents in instruction format. The operands of decoded instructions are also displayed in symbolic notation. The location must be longword aligned.
You can display an entire region of virtual memory by using one or more of the qualifiers /ALL, /SYSTEM, /P0, and /P1 with the EXAMINE command.
Other uses of the EXAMINE command appear in the following examples.
Note
When examining individual locations, addresses are usually symbolized, as described previously. If the SET SYMBOLIZE OFF command is issued, addresses are not symbolized. See the SET SYMBOLIZE command for further details.
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SDA> EXAMINE/PS 7FF95E78
MBZ SPAL MBZ IPL VMM MBZ CURMOD INT PRVMOD
0 00 00000000000 08 0 0 KERN 0 EXEC
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This example shows the display produced by the EXAMINE/PS command.
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SDA> EXAMINE/PTE @^QMMG$GQ_L1_BASE
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The EXAMINE/PTE command displays and formats the level 1 page table entry at FFFFFFFF.FF7FC000.
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SDA> EXAMINE/CONDITION_VALUE R0
%SYSTEM-F-NOPRIV, insufficient privilege or object protection violation
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This example shows the text associated with the condition code in R0.
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SDA> EXAMINE/TIME EXE$GQ_SYSTIME
12-DEC-2001 08:23:07.80
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This example displays the current system as an ASCII absolute time.
Exits from an SDA display or exits from the SDA utility.
EXIT
None.
None.
If SDA is displaying information on a video display terminal---and if that information extends beyond one screen---SDA enters display mode and 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.
See Section 2.6.3 for a description of SDA display mode.
Displays a formatted list of the contents of a block of memory.
FORMAT [/TYPE=block-type] location [/PHYSICAL] [/POSITIVE]
location
Location of the beginning of the data block. The location can be given as any valid SDA expression.
/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 and/or subtype 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./POSITIVE
Symbols that describe negative offsets from the start of the structure are ignored. By default, all symbols for the block type are processed.
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 two bytes that indicate the block type and/or subtype at offsets 0A16 and 0B16, respectively. The type and/or subtype associate 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 type and/or subtype bytes contain a valid block type/subtype combination, SDA retrieves the symbols associated with that type of block (see $DYNDEF) and uses their values to format the block.
For a given block type, all associated symbols have the folloiwng form:
<block_type>$<field>_<name>where field is one of the following:
B Byte W Word L Longword Q Quadword O Octaword 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 the following message:
%SDA-E-NOSYMBOLS, no <block type> symbols found to format this blockIf 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.STBIf 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 and/or subtype. If bytes contain information other than a block type/subtype---or do not contain a valid block type/subtype---SDA either formats the block in a totally inappropriate way, based on the contents of offsets 0A16 and 0B16, or displays the following message:
%SDA-E-INVBLKTYP, invalid block type in specified blockTo format such a block, you must reissue the FORMAT command, using the /TYPE qualifier to designate a block-type.
The FORMAT command produces a three-column display containing the following information:
- 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, including symbolization if a suitable symbol exists.
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
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The READ command loads the symbols from SDA$READ_DIR:SYSDEF.STB into SDA's symbol table. The FORMAT command displays the data structure that begins at G41F81816, a unit control block (UCB). If a field has more than one symbolic name, all such names are displayed. Thus, the field that starts at 8041F82416 has four designations: UCB$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.
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