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.
Format
EVALUATE [{/CONDITION_VALUE|/PS|/PTE
|/[NO]SYMBOLS |/TIME}]
expression
Parameter
expression
SDA expression to be evaluated. Section 2.6.2 describes the components
of SDA expressions.
Qualifiers
/CONDITION_VALUE
Displays the message that the $GETMSG system service obtains for the
value of the expression.
/PS
Evaluates the specified expression in the format of a processor status.
/PTE
Interprets and displays the expression as a page table entry (PTE). The
individual fields of the PTE are separated and an overall description
of the PTE's type is provided.
/SYMBOLS
/NOSYMBOLS
Specifies that all symbols known to be equal to the evaluated
expression are to be listed in alphabetical order. The default behavior
of the EVALUATE command displays only the first five symbols. If
/NOSYMBOLS is specified, only the hexadecimal and decimal values are
displayed.
/TIME
Interprets and displays the expression as a 64-bit time value. Positive
values are interpreted as absolute time; negative values are
interpreted as delta time.
Description
If you do not specify a qualifier, the EVALUATE command interprets and
displays the expression as hexadecimal and decimal values. In addition,
if the expression is equal to the value of a symbol in the SDA symbol
table, that symbol is displayed. If no symbol with this value is known,
the next lower valued symbol is displayed with an appropriate offset
unless the offset is extremely large. (See Section 2.6.2.4 for a
description of how SDA displays symbols and offsets.) The DEFINE
command adds symbols to the SDA symbol table but does not display the
results of the computation. EVALUATE displays the result of the
computation but does not add symbols to the SDA symbol table.
Examples
| #1 |
SDA> EVALUATE -1
Hex = FFFFFFFF.FFFFFFFF Decimal = -1 I
|
The EVALUATE command evaluates a numeric expression, displays the value
of that expression in hexadecimal and decimal notation, and displays a
symbol that has been defined to have an equivalent value.
| #2 |
SDA> EVALUATE 1
Hex = 00000000.00000001 Decimal = 1 CHF$M_CALEXT_CANCEL
CHF$M_FPREGS_VALID
CHF$V_CALEXT_LAST
IRP$M_BUFIO
IRP$M_CLN_READY
|
(remaining symbols suppressed by default)
|
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.
| #3 |
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
|
(remaining symbols suppressed by default)
|
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 |
SDA> EVALUATE (((TEN * 6) + (-1/4)) + 6)
Hex = 00000000.00000042 Decimal = 66
|
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.
| #5 |
SDA> EVALUATE/CONDITION 80000018
%SYSTEM-W-EXQUOTA, exceeded quota
|
This example shows the output of an EVALUATE/CONDITION command.
| #6 |
SDA> EVALUATE/PS 0B03
MBZ SPAL MBZ IPL VMM MBZ CURMOD INT PRVMOD
0 00 00000000000 0B 0 0 KERN 0 USER
|
SDA interprets the entered value 0B03 as though it were a processor
status (PS) and displays the resulting field values.
| #7 |
SDA> EVALUATE/PTE 0BCDFFEE
3 3 2 2 2 1 1 1
1 0 9 7 0 8 6 5 7 6 0
+-+-+--+--------------+-+-+---+-+---------------+-+-----------+-+
|0|0|00| 005E |0|X| 02|1| FF |X| 37 |0|
+-+-+--+--------------+-+-+---+-+---------------+-+-----------+-+
| 00000000 |
+---------------------------------------------------------------+
Global PTE: Owner = S, Read Prot = KESU, Write Prot = KESU, CPY = 0
GPT Index = 00000000
|
|
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.
| #8 |
SDA> EVALUATE/TIME 009A9A4C.843DBA9F
10-OCT-1996 15:59:44.02
|
This example shows the use of the EVALUATE/TIME command.
EXAMINE
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.
Format
EXAMINE [/qualifier[,...]] [location]
Parameter
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.
Qualifiers
/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+20
|
The 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+20
|
The 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.
Description
The following sections describe how to use the EXAMINE command.
Examining Locations
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 memory
|
To 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:
When 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'
|
Decoding Locations
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.
Examining Memory Regions
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
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.
|
Examples
| #1 |
SDA> EXAMINE/PS 7FF95E78
MBZ SPAL MBZ IPL VMM MBZ CURMOD INT PRVMOD
0 00 00000000000 08 0 0 KERN 0 EXEC
|
This example shows the display produced by the EXAMINE/PS command.
| #2 |
SDA> EXAMINE/PTE @^QMMG$GQ_L1_BASE
|
The EXAMINE/PTE command displays and formats the level 1 page table
entry at FFFFFFFF.FF7FC000.
| #3 |
SDA> EXAMINE/CONDITION_VALUE R0
%SYSTEM-F-NOPRIV, insufficient privilege or object protection violation
|
This example shows the text associated with the condition code in R0.
| #4 |
SDA> EXAMINE/TIME EXE$GQ_SYSTIME
12-DEC-2001 08:23:07.80
|
This example displays the current system as an ASCII absolute time.
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 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.
FORMAT
Displays a formatted list of the contents of a block of memory.
Format
FORMAT [/TYPE=block-type] location [/PHYSICAL] [/POSITIVE]
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 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.
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 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)
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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 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
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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
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 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 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.
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
.
.
.
|
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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