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This section describes the gdb/mi commands that manipulate data: examine memory and registers, evaluate expressions, etc.
-data-disassemble
Command-data-disassemble [ -s start-addr -e end-addr ] | [ -f filename -l linenum [ -n lines ] ] -- mode
Where:
$pc
)
The output for each instruction is composed of four fields:
Note that whatever included in the instruction field, is not manipulated directly by gdb/mi, i.e., it is not possible to adjust its format.
There's no direct mapping from this command to the CLI.
Disassemble from the current value of $pc
to $pc + 20
:
(gdb) -data-disassemble -s $pc -e "$pc + 20" -- 0 ^done, asm_insns=[ {address="0x000107c0",func-name="main",offset="4", inst="mov 2, %o0"}, {address="0x000107c4",func-name="main",offset="8", inst="sethi %hi(0x11800), %o2"}, {address="0x000107c8",func-name="main",offset="12", inst="or %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"}, {address="0x000107cc",func-name="main",offset="16", inst="sethi %hi(0x11800), %o2"}, {address="0x000107d0",func-name="main",offset="20", inst="or %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"}] (gdb)
Disassemble the whole main
function. Line 32 is part of
main
.
-data-disassemble -f basics.c -l 32 -- 0 ^done,asm_insns=[ {address="0x000107bc",func-name="main",offset="0", inst="save %sp, -112, %sp"}, {address="0x000107c0",func-name="main",offset="4", inst="mov 2, %o0"}, {address="0x000107c4",func-name="main",offset="8", inst="sethi %hi(0x11800), %o2"}, [...] {address="0x0001081c",func-name="main",offset="96",inst="ret "}, {address="0x00010820",func-name="main",offset="100",inst="restore "}] (gdb)
Disassemble 3 instructions from the start of main
:
(gdb) -data-disassemble -f basics.c -l 32 -n 3 -- 0 ^done,asm_insns=[ {address="0x000107bc",func-name="main",offset="0", inst="save %sp, -112, %sp"}, {address="0x000107c0",func-name="main",offset="4", inst="mov 2, %o0"}, {address="0x000107c4",func-name="main",offset="8", inst="sethi %hi(0x11800), %o2"}] (gdb)
Disassemble 3 instructions from the start of main
in mixed mode:
(gdb) -data-disassemble -f basics.c -l 32 -n 3 -- 1 ^done,asm_insns=[ src_and_asm_line={line="31", file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \ testsuite/gdb.mi/basics.c",line_asm_insn=[ {address="0x000107bc",func-name="main",offset="0", inst="save %sp, -112, %sp"}]}, src_and_asm_line={line="32", file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \ testsuite/gdb.mi/basics.c",line_asm_insn=[ {address="0x000107c0",func-name="main",offset="4", inst="mov 2, %o0"}, {address="0x000107c4",func-name="main",offset="8", inst="sethi %hi(0x11800), %o2"}]}] (gdb)
-data-evaluate-expression
Command-data-evaluate-expression expr
Evaluate expr as an expression. The expression could contain an inferior function call. The function call will execute synchronously. If the expression contains spaces, it must be enclosed in double quotes.
The corresponding gdb commands are `print', `output', and
`call'. In gdbtk
only, there's a corresponding
`gdb_eval' command.
In the following example, the numbers that precede the commands are the tokens described in gdb/mi Command Syntax. Notice how gdb/mi returns the same tokens in its output.
211-data-evaluate-expression A 211^done,value="1" (gdb) 311-data-evaluate-expression &A 311^done,value="0xefffeb7c" (gdb) 411-data-evaluate-expression A+3 411^done,value="4" (gdb) 511-data-evaluate-expression "A + 3" 511^done,value="4" (gdb)
-data-list-changed-registers
Command-data-list-changed-registers
Display a list of the registers that have changed.
gdb doesn't have a direct analog for this command; gdbtk
has the corresponding command `gdb_changed_register_list'.
On a PPC MBX board:
(gdb) -exec-continue ^running (gdb) *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame={ func="main",args=[],file="try.c",fullname="/home/foo/bar/try.c", line="5"} (gdb) -data-list-changed-registers ^done,changed-registers=["0","1","2","4","5","6","7","8","9", "10","11","13","14","15","16","17","18","19","20","21","22","23", "24","25","26","27","28","30","31","64","65","66","67","69"] (gdb)
-data-list-register-names
Command-data-list-register-names [ ( regno )+ ]
Show a list of register names for the current target. If no arguments are given, it shows a list of the names of all the registers. If integer numbers are given as arguments, it will print a list of the names of the registers corresponding to the arguments. To ensure consistency between a register name and its number, the output list may include empty register names.
gdb does not have a command which corresponds to
`-data-list-register-names'. In gdbtk
there is a
corresponding command `gdb_regnames'.
For the PPC MBX board:
(gdb) -data-list-register-names ^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7", "r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18", "r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29", "r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9", "f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20", "f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31", "", "pc","ps","cr","lr","ctr","xer"] (gdb) -data-list-register-names 1 2 3 ^done,register-names=["r1","r2","r3"] (gdb)
-data-list-register-values
Command-data-list-register-values fmt [ ( regno )*]
Display the registers' contents. fmt is the format according to which the registers' contents are to be returned, followed by an optional list of numbers specifying the registers to display. A missing list of numbers indicates that the contents of all the registers must be returned.
Allowed formats for fmt are:
x
o
t
d
r
N
The corresponding gdb commands are `info reg', `info
all-reg', and (in gdbtk
) `gdb_fetch_registers'.
For a PPC MBX board (note: line breaks are for readability only, they don't appear in the actual output):
(gdb) -data-list-register-values r 64 65 ^done,register-values=[{number="64",value="0xfe00a300"}, {number="65",value="0x00029002"}] (gdb) -data-list-register-values x ^done,register-values=[{number="0",value="0xfe0043c8"}, {number="1",value="0x3fff88"},{number="2",value="0xfffffffe"}, {number="3",value="0x0"},{number="4",value="0xa"}, {number="5",value="0x3fff68"},{number="6",value="0x3fff58"}, {number="7",value="0xfe011e98"},{number="8",value="0x2"}, {number="9",value="0xfa202820"},{number="10",value="0xfa202808"}, {number="11",value="0x1"},{number="12",value="0x0"}, {number="13",value="0x4544"},{number="14",value="0xffdfffff"}, {number="15",value="0xffffffff"},{number="16",value="0xfffffeff"}, {number="17",value="0xefffffed"},{number="18",value="0xfffffffe"}, {number="19",value="0xffffffff"},{number="20",value="0xffffffff"}, {number="21",value="0xffffffff"},{number="22",value="0xfffffff7"}, {number="23",value="0xffffffff"},{number="24",value="0xffffffff"}, {number="25",value="0xffffffff"},{number="26",value="0xfffffffb"}, {number="27",value="0xffffffff"},{number="28",value="0xf7bfffff"}, {number="29",value="0x0"},{number="30",value="0xfe010000"}, {number="31",value="0x0"},{number="32",value="0x0"}, {number="33",value="0x0"},{number="34",value="0x0"}, {number="35",value="0x0"},{number="36",value="0x0"}, {number="37",value="0x0"},{number="38",value="0x0"}, {number="39",value="0x0"},{number="40",value="0x0"}, {number="41",value="0x0"},{number="42",value="0x0"}, {number="43",value="0x0"},{number="44",value="0x0"}, {number="45",value="0x0"},{number="46",value="0x0"}, {number="47",value="0x0"},{number="48",value="0x0"}, {number="49",value="0x0"},{number="50",value="0x0"}, {number="51",value="0x0"},{number="52",value="0x0"}, {number="53",value="0x0"},{number="54",value="0x0"}, {number="55",value="0x0"},{number="56",value="0x0"}, {number="57",value="0x0"},{number="58",value="0x0"}, {number="59",value="0x0"},{number="60",value="0x0"}, {number="61",value="0x0"},{number="62",value="0x0"}, {number="63",value="0x0"},{number="64",value="0xfe00a300"}, {number="65",value="0x29002"},{number="66",value="0x202f04b5"}, {number="67",value="0xfe0043b0"},{number="68",value="0xfe00b3e4"}, {number="69",value="0x20002b03"}] (gdb)
-data-read-memory
Command
This command is deprecated, use -data-read-memory-bytes
instead.
-data-read-memory [ -o byte-offset ] address word-format word-size nr-rows nr-cols [ aschar ]
where:
print
command (see Output Formats).
This command displays memory contents as a table of nr-rows by
nr-cols words, each word being word-size bytes. In total,
nr-rows *
nr-cols *
word-size bytes are read
(returned as `total-bytes'). Should less than the requested number
of bytes be returned by the target, the missing words are identified
using `N/A'. The number of bytes read from the target is returned
in `nr-bytes' and the starting address used to read memory in
`addr'.
The address of the next/previous row or page is available in `next-row' and `prev-row', `next-page' and `prev-page'.
The corresponding gdb command is `x'. gdbtk
has
`gdb_get_mem' memory read command.
Read six bytes of memory starting at bytes+6
but then offset by
-6
bytes. Format as three rows of two columns. One byte per
word. Display each word in hex.
(gdb) 9-data-read-memory -o -6 -- bytes+6 x 1 3 2 9^done,addr="0x00001390",nr-bytes="6",total-bytes="6", next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396", prev-page="0x0000138a",memory=[ {addr="0x00001390",data=["0x00","0x01"]}, {addr="0x00001392",data=["0x02","0x03"]}, {addr="0x00001394",data=["0x04","0x05"]}] (gdb)
Read two bytes of memory starting at address shorts + 64
and
display as a single word formatted in decimal.
(gdb) 5-data-read-memory shorts+64 d 2 1 1 5^done,addr="0x00001510",nr-bytes="2",total-bytes="2", next-row="0x00001512",prev-row="0x0000150e", next-page="0x00001512",prev-page="0x0000150e",memory=[ {addr="0x00001510",data=["128"]}] (gdb)
Read thirty two bytes of memory starting at bytes+16
and format
as eight rows of four columns. Include a string encoding with `x'
used as the non-printable character.
(gdb) 4-data-read-memory bytes+16 x 1 8 4 x 4^done,addr="0x000013a0",nr-bytes="32",total-bytes="32", next-row="0x000013c0",prev-row="0x0000139c", next-page="0x000013c0",prev-page="0x00001380",memory=[ {addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"}, {addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"}, {addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"}, {addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"}, {addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"}, {addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"}, {addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"}, {addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"}] (gdb)
-data-read-memory-bytes
Command-data-read-memory-bytes [ -o byte-offset ] address count
where:
This command attempts to read all accessible memory regions in the specified range. First, all regions marked as unreadable in the memory map (if one is defined) will be skipped. See Memory Region Attributes. Second, gdb will attempt to read the remaining regions. For each one, if reading full region results in an errors, gdb will try to read a subset of the region.
In general, every single byte in the region may be readable or not, and the only way to read every readable byte is to try a read at every address, which is not practical. Therefore, gdb will attempt to read all accessible bytes at either beginning or the end of the region, using a binary division scheme. This heuristic works well for reading accross a memory map boundary. Note that if a region has a readable range that is neither at the beginning or the end, gdb will not read it.
The result record (see GDB/MI Result Records) that is output of the command includes a field named `memory' whose content is a list of tuples. Each tuple represent a successfully read memory block and has the following fields:
begin
end
offset
-data-read-memory-bytes
.
contents
The corresponding gdb command is `x'.
(gdb) -data-read-memory-bytes &a 10 ^done,memory=[{begin="0xbffff154",offset="0x00000000", end="0xbffff15e", contents="01000000020000000300"}] (gdb)
-data-write-memory-bytes
Command-data-write-memory-bytes address contents
where:
There's no corresponding gdb command.
(gdb) -data-write-memory-bytes &a "aabbccdd" ^done (gdb)