Info: (gdb) General Query Packets

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gdb: Remote Protocol

gdb: Architecture-Specific Protocol Details

gdb: General Query Packets

E.4 General Query Packets
=========================

Packets starting with 'q' are "general query packets"; packets starting
with 'Q' are "general set packets". General query and set packets are a
semi-unified form for retrieving and sending information to and from the
stub.

The initial letter of a query or set packet is followed by a name
indicating what sort of thing the packet applies to. For example, GDB
may use a 'qSymbol' packet to exchange symbol definitions with the stub.
These packet names follow some conventions:

* The name must not contain commas, colons or semicolons.
* Most GDB query and set packets have a leading upper case letter.
* The names of custom vendor packets should use a company prefix, in
lower case, followed by a period. For example, packets designed at
the Acme Corporation might begin with 'qacme.foo' (for querying
foos) or 'Qacme.bar' (for setting bars).

The name of a query or set packet should be separated from any
parameters by a ':'; the parameters themselves should be separated by
',' or ';'. Stubs must be careful to match the full packet name, and
check for a separator or the end of the packet, in case two packet names
share a common prefix. New packets should not begin with 'qC', 'qP', or
'qL'(1).

Like the descriptions of the other packets, each description here has
a template showing the packet's overall syntax, followed by an
explanation of the packet's meaning. We include spaces in some of the
templates for clarity; these are not part of the packet's syntax. No
GDB packet uses spaces to separate its components.

Here are the currently defined query and set packets:

'QAgent:1'
'QAgent:0'
Turn on or off the agent as a helper to perform some debugging
operations delegated from GDB (Control Agent).

'QAllow:OP:VAL...'
Specify which operations GDB expects to request of the target, as a
semicolon-separated list of operation name and value pairs.
Possible values for OP include 'WriteReg', 'WriteMem',
'InsertBreak', 'InsertTrace', 'InsertFastTrace', and 'Stop'. VAL
is either 0, indicating that GDB will not request the operation, or
1, indicating that it may. (The target can then use this to set up
its own internals optimally, for instance if the debugger never
expects to insert breakpoints, it may not need to install its own
trap handler.)

'qC'
Return the current thread ID.

Reply:
'QC THREAD-ID'
Where THREAD-ID is a thread ID as documented in
thread-id syntax.
'(anything else)'
Any other reply implies the old thread ID.

'qCRC:ADDR,LENGTH'
Compute the CRC checksum of a block of memory using CRC-32 defined
in IEEE 802.3. The CRC is computed byte at a time, taking the most
significant bit of each byte first. The initial pattern code
'0xffffffff' is used to ensure leading zeros affect the CRC.

_Note:_ This is the same CRC used in validating separate debug
files (Debugging Information in Separate Files Separate
Debug Files.). However the algorithm is slightly different. When
validating separate debug files, the CRC is computed taking the
_least_ significant bit of each byte first, and the final result is
inverted to detect trailing zeros.

Reply:
'E NN'
An error (such as memory fault)
'C CRC32'
The specified memory region's checksum is CRC32.

'QDisableRandomization:VALUE'
Some target operating systems will randomize the virtual address
space of the inferior process as a security feature, but provide a
feature to disable such randomization, e.g. to allow for a more
deterministic debugging experience. On such systems, this packet
with a VALUE of 1 directs the target to disable address space
randomization for processes subsequently started via 'vRun'
packets, while a packet with a VALUE of 0 tells the target to
enable address space randomization.

This packet is only available in extended mode (extended
mode).

Reply:
'OK'
The request succeeded.

'E NN'
An error occurred. The error number NN is given as hex
digits.

''
An empty reply indicates that 'QDisableRandomization' is not
supported by the stub.

This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (
qSupported). This should only be done on targets that actually
support disabling address space randomization.

'QStartupWithShell:VALUE'
On UNIX-like targets, it is possible to start the inferior using a
shell program. This is the default behavior on both GDB and
'gdbserver' (set startup-with-shell). This packet is used
to inform 'gdbserver' whether it should start the inferior using a
shell or not.

If VALUE is '0', 'gdbserver' will not use a shell to start the
inferior. If VALUE is '1', 'gdbserver' will use a shell to start
the inferior. All other values are considered an error.

This packet is only available in extended mode (extended
mode).

Reply:
'OK'
The request succeeded.

'E NN'
An error occurred. The error number NN is given as hex
digits.

Use of this packet is controlled by the 'set startup-with-shell'
command; set startup-with-shell.

'QEnvironmentHexEncoded:HEX-VALUE'
On UNIX-like targets, it is possible to set environment variables
that will be passed to the inferior during the startup process.
This packet is used to inform 'gdbserver' of an environment
variable that has been defined by the user on GDB (set
environment).

The packet is composed by HEX-VALUE, an hex encoded representation
of the NAME=VALUE format representing an environment variable. The
name of the environment variable is represented by NAME, and the
value to be assigned to the environment variable is represented by
VALUE. If the variable has no value (i.e., the value is 'null'),
then VALUE will not be present.

This packet is only available in extended mode (extended
mode).

Reply:
'OK'
The request succeeded.

This packet is related to the 'set environment' command; set
environment.

'QEnvironmentUnset:HEX-VALUE'
On UNIX-like targets, it is possible to unset environment variables
before starting the inferior in the remote target. This packet is
used to inform 'gdbserver' of an environment variable that has been
unset by the user on GDB (unset environment).

The packet is composed by HEX-VALUE, an hex encoded representation
of the name of the environment variable to be unset.

This packet is only available in extended mode (extended
mode).

Reply:
'OK'
The request succeeded.

This packet is related to the 'unset environment' command;
unset environment.

'QEnvironmentReset'
On UNIX-like targets, this packet is used to reset the state of
environment variables in the remote target before starting the
inferior. In this context, reset means unsetting all environment
variables that were previously set by the user (i.e., were not
initially present in the environment). It is sent to 'gdbserver'
QEnvironmentHexEncoded::) and the 'QEnvironmentUnset' (
QEnvironmentUnset) packets.

This packet is only available in extended mode (extended
mode).

Reply:
'OK'
The request succeeded.

'QSetWorkingDir:[DIRECTORY]'
This packet is used to inform the remote server of the intended
current working directory for programs that are going to be
executed.

The packet is composed by DIRECTORY, an hex encoded representation
of the directory that the remote inferior will use as its current
working directory. If DIRECTORY is an empty string, the remote
server should reset the inferior's current working directory to its
original, empty value.

This packet is only available in extended mode (extended
mode).

Reply:
'OK'
The request succeeded.

'qfThreadInfo'
'qsThreadInfo'
Obtain a list of all active thread IDs from the target (OS). Since
there may be too many active threads to fit into one reply packet,
this query works iteratively: it may require more than one
query/reply sequence to obtain the entire list of threads. The
first query of the sequence will be the 'qfThreadInfo' query;
subsequent queries in the sequence will be the 'qsThreadInfo'
query.

NOTE: This packet replaces the 'qL' query (see below).

Reply:
'm THREAD-ID'
A single thread ID
'm THREAD-ID,THREAD-ID...'
a comma-separated list of thread IDs
'l'
(lower case letter 'L') denotes end of list.

In response to each query, the target will reply with a list of one
or more thread IDs, separated by commas. GDB will respond to each
reply with a request for more thread ids (using the 'qs' form of
the query), until the target responds with 'l' (lower-case ell, for
"last"). Refer to thread-id syntax, for the format of the
THREAD-ID fields.

_Note: GDB will send the 'qfThreadInfo' query during the initial
connection with the remote target, and the very first thread ID
mentioned in the reply will be stopped by GDB in a subsequent
message. Therefore, the stub should ensure that the first thread
ID in the 'qfThreadInfo' reply is suitable for being stopped by
GDB._

'qGetTLSAddr:THREAD-ID,OFFSET,LM'
Fetch the address associated with thread local storage specified by
THREAD-ID, OFFSET, and LM.

THREAD-ID is the thread ID associated with the thread for which to
fetch the TLS address. thread-id syntax.

OFFSET is the (big endian, hex encoded) offset associated with the
thread local variable. (This offset is obtained from the debug
information associated with the variable.)

LM is the (big endian, hex encoded) OS/ABI-specific encoding of the
load module associated with the thread local storage. For example,
a GNU/Linux system will pass the link map address of the shared
object associated with the thread local storage under
consideration. Other operating environments may choose to
represent the load module differently, so the precise meaning of
this parameter will vary.

Reply:
'XX...'
Hex encoded (big endian) bytes representing the address of the
thread local storage requested.

'E NN'
An error occurred. The error number NN is given as hex
digits.

''
An empty reply indicates that 'qGetTLSAddr' is not supported
by the stub.

'qGetTIBAddr:THREAD-ID'
Fetch address of the Windows OS specific Thread Information Block.

THREAD-ID is the thread ID associated with the thread.

Reply:
'XX...'
Hex encoded (big endian) bytes representing the linear address
of the thread information block.

'E NN'
An error occured. This means that either the thread was not
found, or the address could not be retrieved.

''
An empty reply indicates that 'qGetTIBAddr' is not supported
by the stub.

'qL STARTFLAG THREADCOUNT NEXTTHREAD'
Obtain thread information from RTOS. Where: STARTFLAG (one hex
digit) is one to indicate the first query and zero to indicate a
subsequent query; THREADCOUNT (two hex digits) is the maximum
number of threads the response packet can contain; and NEXTTHREAD
(eight hex digits), for subsequent queries (STARTFLAG is zero), is
returned in the response as ARGTHREAD.

Don't use this packet; use the 'qfThreadInfo' query instead (see
above).

Reply:
'qM COUNT DONE ARGTHREAD THREAD...'
Where: COUNT (two hex digits) is the number of threads being
returned; DONE (one hex digit) is zero to indicate more
threads and one indicates no further threads; ARGTHREADID
(eight hex digits) is NEXTTHREAD from the request packet;
THREAD... is a sequence of thread IDs, THREADID (eight hex
digits), from the target. See
'remote.c:parse_threadlist_response()'.

'qOffsets'
Get section offsets that the target used when relocating the
downloaded image.

Reply:
'Text=XXX;Data=YYY[;Bss=ZZZ]'
Relocate the 'Text' section by XXX from its original address.
Relocate the 'Data' section by YYY from its original address.
If the object file format provides segment information (e.g.
ELF 'PT_LOAD' program headers), GDB will relocate entire
segments by the supplied offsets.

_Note: while a 'Bss' offset may be included in the response,
GDB ignores this and instead applies the 'Data' offset to the
'Bss' section._

'TextSeg=XXX[;DataSeg=YYY]'
Relocate the first segment of the object file, which
conventionally contains program code, to a starting address of
XXX. If 'DataSeg' is specified, relocate the second segment,
which conventionally contains modifiable data, to a starting
address of YYY. GDB will report an error if the object file
does not contain segment information, or does not contain at
least as many segments as mentioned in the reply. Extra
segments are kept at fixed offsets relative to the last
relocated segment.

'qP MODE THREAD-ID'
Returns information on THREAD-ID. Where: MODE is a hex encoded 32
bit mode; THREAD-ID is a thread ID (thread-id syntax).

Don't use this packet; use the 'qThreadExtraInfo' query instead
(see below).

Reply: see 'remote.c:remote_unpack_thread_info_response()'.

'QNonStop:1'
'QNonStop:0'
Enter non-stop ('QNonStop:1') or all-stop ('QNonStop:0') mode.
Remote Non-Stop, for more information.

Reply:
'OK'
The request succeeded.

'E NN'
An error occurred. The error number NN is given as hex
digits.

''
An empty reply indicates that 'QNonStop' is not supported by
the stub.

This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (
qSupported). Use of this packet is controlled by the 'set
non-stop' command; Non-Stop Mode.

'QCatchSyscalls:1 [;SYSNO]...'
'QCatchSyscalls:0'
Enable ('QCatchSyscalls:1') or disable ('QCatchSyscalls:0')
catching syscalls from the inferior process.

For 'QCatchSyscalls:1', each listed syscall SYSNO (encoded in hex)
should be reported to GDB. If no syscall SYSNO is listed, every
system call should be reported.

Note that if a syscall not in the list is reported, GDB will still
filter the event according to its own list from all corresponding
'catch syscall' commands. However, it is more efficient to only
report the requested syscalls.

Multiple 'QCatchSyscalls:1' packets do not combine; any earlier
'QCatchSyscalls:1' list is completely replaced by the new list.

If the inferior process execs, the state of 'QCatchSyscalls' is
kept for the new process too. On targets where exec may affect
syscall numbers, for example with exec between 32 and 64-bit
processes, the client should send a new packet with the new syscall
list.

Reply:
'OK'
The request succeeded.

'E NN'
An error occurred. NN are hex digits.

''
An empty reply indicates that 'QCatchSyscalls' is not
supported by the stub.

Use of this packet is controlled by the 'set remote catch-syscalls'
command (set remote catch-syscalls Remote Configuration.).
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (
qSupported).

'QPassSignals: SIGNAL [;SIGNAL]...'
Each listed SIGNAL should be passed directly to the inferior
process. Signals are numbered identically to continue packets and
stop replies (Stop Reply Packets). Each SIGNAL list item
should be strictly greater than the previous item. These signals
do not need to stop the inferior, or be reported to GDB. All other
signals should be reported to GDB. Multiple 'QPassSignals' packets
do not combine; any earlier 'QPassSignals' list is completely
replaced by the new list. This packet improves performance when
using 'handle SIGNAL nostop noprint pass'.

Reply:
'OK'
The request succeeded.

'E NN'
An error occurred. The error number NN is given as hex
digits.

''
An empty reply indicates that 'QPassSignals' is not supported
by the stub.

Use of this packet is controlled by the 'set remote pass-signals'
command (set remote pass-signals Remote Configuration.).
This packet is not probed by default; the remote stub must request
it, by supplying an appropriate 'qSupported' response (
qSupported).

'QProgramSignals: SIGNAL [;SIGNAL]...'
Each listed SIGNAL may be delivered to the inferior process.
Others should be silently discarded.

In some cases, the remote stub may need to decide whether to
deliver a signal to the program or not without GDB involvement.
One example of that is while detaching -- the program's threads may
have stopped for signals that haven't yet had a chance of being
reported to GDB, and so the remote stub can use the signal list
specified by this packet to know whether to deliver or ignore those
pending signals.

This does not influence whether to deliver a signal as requested by
a resumption packet (vCont packet).

Signals are numbered identically to continue packets and stop
replies (Stop Reply Packets). Each SIGNAL list item should
be strictly greater than the previous item. Multiple
'QProgramSignals' packets do not combine; any earlier
'QProgramSignals' list is completely replaced by the new list.

Reply:
'OK'
The request succeeded.

'E NN'
An error occurred. The error number NN is given as hex
digits.

''
An empty reply indicates that 'QProgramSignals' is not
supported by the stub.

Use of this packet is controlled by the 'set remote
program-signals' command (set remote program-signals Remote
Configuration.). This packet is not probed by default; the remote
stub must request it, by supplying an appropriate 'qSupported'
response (qSupported).

'QThreadEvents:1'
'QThreadEvents:0'

Enable ('QThreadEvents:1') or disable ('QThreadEvents:0') reporting
of thread create and exit events. thread create event, for
the reply specifications. For example, this is used in non-stop
mode when GDB stops a set of threads and synchronously waits for
the their corresponding stop replies. Without exit events, if one
of the threads exits, GDB would hang forever not knowing that it
should no longer expect a stop for that same thread. GDB does not
enable this feature unless the stub reports that it supports it by
including 'QThreadEvents+' in its 'qSupported' reply.

Reply:
'OK'
The request succeeded.

'E NN'
An error occurred. The error number NN is given as hex
digits.

''
An empty reply indicates that 'QThreadEvents' is not supported
by the stub.

Use of this packet is controlled by the 'set remote thread-events'
command (set remote thread-events Remote Configuration.).

'qRcmd,COMMAND'
COMMAND (hex encoded) is passed to the local interpreter for
execution. Invalid commands should be reported using the output
string. Before the final result packet, the target may also
respond with a number of intermediate 'OOUTPUT' console output
packets. _Implementors should note that providing access to a
stubs's interpreter may have security implications_.

Reply:
'OK'
A command response with no output.
'OUTPUT'
A command response with the hex encoded output string OUTPUT.
'E NN'
Indicate a badly formed request.
''
An empty reply indicates that 'qRcmd' is not recognized.

(Note that the 'qRcmd' packet's name is separated from the command
by a ',', not a ':', contrary to the naming conventions above.
Please don't use this packet as a model for new packets.)

'qSearch:memory:ADDRESS;LENGTH;SEARCH-PATTERN'
Search LENGTH bytes at ADDRESS for SEARCH-PATTERN. Both ADDRESS
and LENGTH are encoded in hex; SEARCH-PATTERN is a sequence of
bytes, also hex encoded.

Reply:
'0'
The pattern was not found.
'1,address'
The pattern was found at ADDRESS.
'E NN'
A badly formed request or an error was encountered while
searching memory.
''
An empty reply indicates that 'qSearch:memory' is not
recognized.

'QStartNoAckMode'
Request that the remote stub disable the normal '+'/'-' protocol
acknowledgments (Packet Acknowledgment).

Reply:
'OK'
The stub has switched to no-acknowledgment mode. GDB
acknowledges this reponse, but neither the stub nor GDB shall
send or expect further '+'/'-' acknowledgments in the current
connection.
''
An empty reply indicates that the stub does not support
no-acknowledgment mode.

'qSupported [:GDBFEATURE [;GDBFEATURE]... ]'
Tell the remote stub about features supported by GDB, and query the
stub for features it supports. This packet allows GDB and the
remote stub to take advantage of each others' features.
'qSupported' also consolidates multiple feature probes at startup,
to improve GDB performance--a single larger packet performs better
than multiple smaller probe packets on high-latency links. Some
features may enable behavior which must not be on by default, e.g.
because it would confuse older clients or stubs. Other features
may describe packets which could be automatically probed for, but
are not. These features must be reported before GDB will use them.
This "default unsupported" behavior is not appropriate for all
packets, but it helps to keep the initial connection time under
control with new versions of GDB which support increasing numbers
of packets.

Reply:
'STUBFEATURE [;STUBFEATURE]...'
The stub supports or does not support each returned
STUBFEATURE, depending on the form of each STUBFEATURE (see
below for the possible forms).
''
An empty reply indicates that 'qSupported' is not recognized,
or that no features needed to be reported to GDB.

The allowed forms for each feature (either a GDBFEATURE in the
'qSupported' packet, or a STUBFEATURE in the response) are:

'NAME=VALUE'
The remote protocol feature NAME is supported, and associated
with the specified VALUE. The format of VALUE depends on the
feature, but it must not include a semicolon.
'NAME+'
The remote protocol feature NAME is supported, and does not
need an associated value.
'NAME-'
The remote protocol feature NAME is not supported.
'NAME?'
The remote protocol feature NAME may be supported, and GDB
should auto-detect support in some other way when it is
needed. This form will not be used for GDBFEATURE
notifications, but may be used for STUBFEATURE responses.

Whenever the stub receives a 'qSupported' request, the supplied set
of GDB features should override any previous request. This allows
GDB to put the stub in a known state, even if the stub had
previously been communicating with a different version of GDB.

The following values of GDBFEATURE (for the packet sent by GDB) are
defined:

'multiprocess'
This feature indicates whether GDB supports multiprocess
extensions to the remote protocol. GDB does not use such
extensions unless the stub also reports that it supports them
by including 'multiprocess+' in its 'qSupported' reply.
multiprocess extensions, for details.

'xmlRegisters'
This feature indicates that GDB supports the XML target
description. If the stub sees 'xmlRegisters=' with target
specific strings separated by a comma, it will report register
description.

'qRelocInsn'
This feature indicates whether GDB supports the 'qRelocInsn'
packet (Relocate instruction reply packet Tracepoint
Packets.).

'swbreak'
This feature indicates whether GDB supports the swbreak stop
reason in stop replies. swbreak stop reason, for
details.

'hwbreak'
This feature indicates whether GDB supports the hwbreak stop
reason in stop replies. swbreak stop reason, for
details.

'fork-events'
This feature indicates whether GDB supports fork event
extensions to the remote protocol. GDB does not use such
extensions unless the stub also reports that it supports them
by including 'fork-events+' in its 'qSupported' reply.

'vfork-events'
This feature indicates whether GDB supports vfork event
extensions to the remote protocol. GDB does not use such
extensions unless the stub also reports that it supports them
by including 'vfork-events+' in its 'qSupported' reply.

'exec-events'
This feature indicates whether GDB supports exec event
extensions to the remote protocol. GDB does not use such
extensions unless the stub also reports that it supports them
by including 'exec-events+' in its 'qSupported' reply.

'vContSupported'
This feature indicates whether GDB wants to know the supported
actions in the reply to 'vCont?' packet.

Stubs should ignore any unknown values for GDBFEATURE. Any GDB
which sends a 'qSupported' packet supports receiving packets of
unlimited length (earlier versions of GDB may reject overly long
responses). Additional values for GDBFEATURE may be defined in the
future to let the stub take advantage of new features in GDB, e.g.
incompatible improvements in the remote protocol--the
'multiprocess' feature is an example of such a feature. The stub's
reply should be independent of the GDBFEATURE entries sent by GDB;
first GDB describes all the features it supports, and then the stub
replies with all the features it supports.

Similarly, GDB will silently ignore unrecognized stub feature
responses, as long as each response uses one of the standard forms.

Some features are flags. A stub which supports a flag feature
should respond with a '+' form response. Other features require
values, and the stub should respond with an '=' form response.

Each feature has a default value, which GDB will use if
'qSupported' is not available or if the feature is not mentioned in
the 'qSupported' response. The default values are fixed; a stub is
free to omit any feature responses that match the defaults.

Not all features can be probed, but for those which can, the
probing mechanism is useful: in some cases, a stub's internal
architecture may not allow the protocol layer to know some
information about the underlying target in advance. This is
especially common in stubs which may be configured for multiple
targets.

These are the currently defined stub features and their properties:

Feature Name Value Default Probe
Required Allowed

'PacketSize' Yes '-' No

'qXfer:auxv:read' No '-' Yes

'qXfer:btrace:read' No '-' Yes

'qXfer:btrace-conf:read' No '-' Yes

'qXfer:exec-file:read' No '-' Yes

'qXfer:features:read' No '-' Yes

'qXfer:libraries:read' No '-' Yes

'qXfer:libraries-svr4:read'No '-' Yes

'augmented-libraries-svr4-read'No '-' No

'qXfer:memory-map:read' No '-' Yes

'qXfer:sdata:read' No '-' Yes

'qXfer:spu:read' No '-' Yes

'qXfer:spu:write' No '-' Yes

'qXfer:siginfo:read' No '-' Yes

'qXfer:siginfo:write' No '-' Yes

'qXfer:threads:read' No '-' Yes

'qXfer:traceframe-info:read'No '-' Yes

'qXfer:uib:read' No '-' Yes

'qXfer:fdpic:read' No '-' Yes

'Qbtrace:off' Yes '-' Yes

'Qbtrace:bts' Yes '-' Yes

'Qbtrace:pt' Yes '-' Yes

'Qbtrace-conf:bts:size' Yes '-' Yes

'Qbtrace-conf:pt:size' Yes '-' Yes

'QNonStop' No '-' Yes

'QCatchSyscalls' No '-' Yes

'QPassSignals' No '-' Yes

'QStartNoAckMode' No '-' Yes

'multiprocess' No '-' No

'ConditionalBreakpoints' No '-' No

'ConditionalTracepoints' No '-' No

'ReverseContinue' No '-' No

'ReverseStep' No '-' No

'TracepointSource' No '-' No

'QAgent' No '-' No

'QAllow' No '-' No

'QDisableRandomization' No '-' No

'EnableDisableTracepoints'No '-' No

'QTBuffer:size' No '-' No

'tracenz' No '-' No

'BreakpointCommands' No '-' No

'swbreak' No '-' No

'hwbreak' No '-' No

'fork-events' No '-' No

'vfork-events' No '-' No

'exec-events' No '-' No

'QThreadEvents' No '-' No

'no-resumed' No '-' No

These are the currently defined stub features, in more detail:

'PacketSize=BYTES'
The remote stub can accept packets up to at least BYTES in
length. GDB will send packets up to this size for bulk
transfers, and will never send larger packets. This is a
limit on the data characters in the packet, including the
frame and checksum. There is no trailing NUL byte in a remote
protocol packet; if the stub stores packets in a
NUL-terminated format, it should allow an extra byte in its
buffer for the NUL. If this stub feature is not supported, GDB
guesses based on the size of the 'g' packet response.

'qXfer:auxv:read'
The remote stub understands the 'qXfer:auxv:read' packet
(qXfer auxiliary vector read).

'qXfer:btrace:read'
The remote stub understands the 'qXfer:btrace:read' packet
(qXfer btrace read).

'qXfer:btrace-conf:read'
The remote stub understands the 'qXfer:btrace-conf:read'
packet (qXfer btrace-conf read).

'qXfer:exec-file:read'
The remote stub understands the 'qXfer:exec-file:read' packet
(qXfer executable filename read).

'qXfer:features:read'
The remote stub understands the 'qXfer:features:read' packet
(qXfer target description read).

'qXfer:libraries:read'
The remote stub understands the 'qXfer:libraries:read' packet
(qXfer library list read).

'qXfer:libraries-svr4:read'
The remote stub understands the 'qXfer:libraries-svr4:read'
packet (qXfer svr4 library list read).

'augmented-libraries-svr4-read'
The remote stub understands the augmented form of the
'qXfer:libraries-svr4:read' packet (qXfer svr4 library
list read).

'qXfer:memory-map:read'
The remote stub understands the 'qXfer:memory-map:read' packet
(qXfer memory map read).

'qXfer:sdata:read'
The remote stub understands the 'qXfer:sdata:read' packet
(qXfer sdata read).

'qXfer:spu:read'
The remote stub understands the 'qXfer:spu:read' packet (
qXfer spu read).

'qXfer:spu:write'
The remote stub understands the 'qXfer:spu:write' packet
(qXfer spu write).

'qXfer:siginfo:read'
The remote stub understands the 'qXfer:siginfo:read' packet
(qXfer siginfo read).

'qXfer:siginfo:write'
The remote stub understands the 'qXfer:siginfo:write' packet
(qXfer siginfo write).

'qXfer:threads:read'
The remote stub understands the 'qXfer:threads:read' packet
(qXfer threads read).

'qXfer:traceframe-info:read'
The remote stub understands the 'qXfer:traceframe-info:read'
packet (qXfer traceframe info read).

'qXfer:uib:read'
The remote stub understands the 'qXfer:uib:read' packet (
qXfer unwind info block).

'qXfer:fdpic:read'
The remote stub understands the 'qXfer:fdpic:read' packet
(qXfer fdpic loadmap read).

'QNonStop'
The remote stub understands the 'QNonStop' packet (
QNonStop).

'QCatchSyscalls'
The remote stub understands the 'QCatchSyscalls' packet (
QCatchSyscalls).

'QPassSignals'
The remote stub understands the 'QPassSignals' packet (
QPassSignals).

'QStartNoAckMode'
The remote stub understands the 'QStartNoAckMode' packet and
prefers to operate in no-acknowledgment mode. Packet
Acknowledgment.

'multiprocess'
The remote stub understands the multiprocess extensions to the
remote protocol syntax. The multiprocess extensions affect
the syntax of thread IDs in both packets and replies (
thread-id syntax), and add process IDs to the 'D' packet and
'W' and 'X' replies. Note that reporting this feature
indicates support for the syntactic extensions only, not that
the stub necessarily supports debugging of more than one
process at a time. The stub must not use multiprocess
extensions in packet replies unless GDB has also indicated it
supports them in its 'qSupported' request.

'qXfer:osdata:read'
The remote stub understands the 'qXfer:osdata:read' packet
((qXfer osdata read).

'ConditionalBreakpoints'
The target accepts and implements evaluation of conditional
expressions defined for breakpoints. The target will only
report breakpoint triggers when such conditions are true
(Break Conditions Conditions.).

'ConditionalTracepoints'
The remote stub accepts and implements conditional expressions
defined for tracepoints (Tracepoint Conditions).

'ReverseContinue'
The remote stub accepts and implements the reverse continue
packet (bc).

'ReverseStep'
The remote stub accepts and implements the reverse step packet
(bs).

'TracepointSource'
The remote stub understands the 'QTDPsrc' packet that supplies
the source form of tracepoint definitions.

'QAgent'
The remote stub understands the 'QAgent' packet.

'QAllow'
The remote stub understands the 'QAllow' packet.

'QDisableRandomization'
The remote stub understands the 'QDisableRandomization'
packet.

'StaticTracepoint'
The remote stub supports static tracepoints.

'InstallInTrace'
The remote stub supports installing tracepoint in tracing.

'EnableDisableTracepoints'
The remote stub supports the 'QTEnable' (QTEnable) and
'QTDisable' (QTDisable) packets that allow tracepoints
to be enabled and disabled while a trace experiment is
running.

'QTBuffer:size'
QTBuffer-size::) packet that allows to change the size of the
trace buffer.

'tracenz'
The remote stub supports the 'tracenz' bytecode for collecting
strings. See Bytecode Descriptions for details about
the bytecode.

'BreakpointCommands'
The remote stub supports running a breakpoint's command list
itself, rather than reporting the hit to GDB.

'Qbtrace:off'
The remote stub understands the 'Qbtrace:off' packet.

'Qbtrace:bts'
The remote stub understands the 'Qbtrace:bts' packet.

'Qbtrace:pt'
The remote stub understands the 'Qbtrace:pt' packet.

'Qbtrace-conf:bts:size'
The remote stub understands the 'Qbtrace-conf:bts:size'
packet.

'Qbtrace-conf:pt:size'
The remote stub understands the 'Qbtrace-conf:pt:size' packet.

'swbreak'
The remote stub reports the 'swbreak' stop reason for memory
breakpoints.

'hwbreak'
The remote stub reports the 'hwbreak' stop reason for hardware
breakpoints.

'fork-events'
The remote stub reports the 'fork' stop reason for fork
events.

'vfork-events'
The remote stub reports the 'vfork' stop reason for vfork
events and vforkdone events.

'exec-events'
The remote stub reports the 'exec' stop reason for exec
events.

'vContSupported'
The remote stub reports the supported actions in the reply to
'vCont?' packet.

'QThreadEvents'
The remote stub understands the 'QThreadEvents' packet.

'no-resumed'
The remote stub reports the 'N' stop reply.

'qSymbol::'
Notify the target that GDB is prepared to serve symbol lookup
requests. Accept requests from the target for the values of
symbols.

Reply:
'OK'
The target does not need to look up any (more) symbols.
'qSymbol:SYM_NAME'
The target requests the value of symbol SYM_NAME (hex
encoded). GDB may provide the value by using the
'qSymbol:SYM_VALUE:SYM_NAME' message, described below.

'qSymbol:SYM_VALUE:SYM_NAME'
Set the value of SYM_NAME to SYM_VALUE.

SYM_NAME (hex encoded) is the name of a symbol whose value the
target has previously requested.

SYM_VALUE (hex) is the value for symbol SYM_NAME. If GDB cannot
supply a value for SYM_NAME, then this field will be empty.

Reply:
'OK'
The target does not need to look up any (more) symbols.
'qSymbol:SYM_NAME'
The target requests the value of a new symbol SYM_NAME (hex
encoded). GDB will continue to supply the values of symbols
(if available), until the target ceases to request them.

'qTBuffer'
'QTBuffer'
'QTDisconnected'
'QTDP'
'QTDPsrc'
'QTDV'
'qTfP'
'qTfV'
'QTFrame'
'qTMinFTPILen'

Tracepoint Packets.

'qThreadExtraInfo,THREAD-ID'
Obtain from the target OS a printable string description of thread
attributes for the thread THREAD-ID; see thread-id syntax,
for the forms of THREAD-ID. This string may contain anything that
the target OS thinks is interesting for GDB to tell the user about
the thread. The string is displayed in GDB's 'info threads'
display. Some examples of possible thread extra info strings are
'Runnable', or 'Blocked on Mutex'.

Reply:
'XX...'
Where 'XX...' is a hex encoding of ASCII data, comprising the
printable string containing the extra information about the
thread's attributes.

(Note that the 'qThreadExtraInfo' packet's name is separated from
the command by a ',', not a ':', contrary to the naming conventions
above. Please don't use this packet as a model for new packets.)

'QTNotes'
'qTP'
'QTSave'
'qTsP'
'qTsV'
'QTStart'
'QTStop'
'QTEnable'
'QTDisable'
'QTinit'
'QTro'
'qTStatus'
'qTV'
'qTfSTM'
'qTsSTM'
'qTSTMat'
Tracepoint Packets.

'qXfer:OBJECT:read:ANNEX:OFFSET,LENGTH'
Read uninterpreted bytes from the target's special data area
identified by the keyword OBJECT. Request LENGTH bytes starting at
OFFSET bytes into the data. The content and encoding of ANNEX is
specific to OBJECT; it can supply additional details about what
data to access.

Reply:
'm DATA'
Data DATA (Binary Data) has been read from the target.
There may be more data at a higher address (although it is
permitted to return 'm' even for the last valid block of data,
as long as at least one byte of data was read). It is
possible for DATA to have fewer bytes than the LENGTH in the
request.

'l DATA'
Data DATA (Binary Data) has been read from the target.
There is no more data to be read. It is possible for DATA to
have fewer bytes than the LENGTH in the request.

'l'
The OFFSET in the request is at the end of the data. There is
no more data to be read.

'E00'
The request was malformed, or ANNEX was invalid.

'E NN'
The offset was invalid, or there was an error encountered
reading the data. The NN part is a hex-encoded 'errno' value.

''
An empty reply indicates the OBJECT string was not recognized
by the stub, or that the object does not support reading.

Here are the specific requests of this form defined so far. All
the 'qXfer:OBJECT:read:...' requests use the same reply formats,
listed above.

'qXfer:auxv:read::OFFSET,LENGTH'
Access the target's "auxiliary vector". auxiliary
vector OS Information. Note ANNEX must be empty.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:btrace:read:ANNEX:OFFSET,LENGTH'

Return a description of the current branch trace.
Branch Trace Format. The annex part of the generic 'qXfer'
packet may have one of the following values:

'all'
Returns all available branch trace.

'new'
Returns all available branch trace if the branch trace
changed since the last read request.

'delta'
Returns the new branch trace since the last read request.
Adds a new block to the end of the trace that begins at
zero and ends at the source location of the first branch
in the trace buffer. This extra block is used to stitch
traces together.

If the trace buffer overflowed, returns an error
indicating the overflow.

This packet is not probed by default; the remote stub must
request it by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:btrace-conf:read::OFFSET,LENGTH'

Return a description of the current branch trace
configuration. Branch Trace Configuration Format.

This packet is not probed by default; the remote stub must
request it by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:exec-file:read:ANNEX:OFFSET,LENGTH'
Return the full absolute name of the file that was executed to
create a process running on the remote system. The annex
specifies the numeric process ID of the process to query,
encoded as a hexadecimal number. If the annex part is empty
the remote stub should return the filename corresponding to
the currently executing process.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:features:read:ANNEX:OFFSET,LENGTH'
Access the "target description". Target Descriptions.
The annex specifies which XML document to access. The main
description is always loaded from the 'target.xml' annex.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:libraries:read:ANNEX:OFFSET,LENGTH'
Access the target's list of loaded libraries. Library
List Format. The annex part of the generic 'qXfer' packet
must be empty (qXfer read).

Targets which maintain a list of libraries in the program's
memory do not need to implement this packet; it is designed
for platforms where the operating system manages the list of
loaded libraries.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:libraries-svr4:read:ANNEX:OFFSET,LENGTH'
Access the target's list of loaded libraries when the target
is an SVR4 platform. Library List Format for SVR4
Targets. The annex part of the generic 'qXfer' packet must
be empty unless the remote stub indicated it supports the
augmented form of this packet by supplying an appropriate
DONTPRINTYET 'qSupported' response (qXfer read, *noteDONTPRINTYET 'qSupported' response (qXfer read,
qSupported).

This packet is optional for better performance on SVR4
targets. GDB uses memory read packets to read the SVR4
library list otherwise.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

If the remote stub indicates it supports the augmented form of
this packet then the annex part of the generic 'qXfer' packet
may contain a semicolon-separated list of 'NAME=VALUE'
arguments. The currently supported arguments are:

'start=ADDRESS'
A hexadecimal number specifying the address of the
'struct link_map' to start reading the library list from.
If unset or zero then the first 'struct link_map' in the
library list will be chosen as the starting point.

'prev=ADDRESS'
A hexadecimal number specifying the address of the
'struct link_map' immediately preceding the 'struct
link_map' specified by the 'start' argument. If unset or
zero then the remote stub will expect that no 'struct
link_map' exists prior to the starting point.

Arguments that are not understood by the remote stub will be
silently ignored.

'qXfer:memory-map:read::OFFSET,LENGTH'
Access the target's "memory-map". Memory Map Format.
The annex part of the generic 'qXfer' packet must be empty
(qXfer read).

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:sdata:read::OFFSET,LENGTH'

Read contents of the extra collected static tracepoint marker
information. The annex part of the generic 'qXfer' packet
DONTPRINTYET must be empty (qXfer read). *NoteTracepoint Action
DONTPRINTYET must be empty (qXfer read). Tracepoint Action

Lists Tracepoint Actions.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:siginfo:read::OFFSET,LENGTH'
Read contents of the extra signal information on the target
system. The annex part of the generic 'qXfer' packet must be
empty (qXfer read).

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:spu:read:ANNEX:OFFSET,LENGTH'
Read contents of an 'spufs' file on the target system. The
annex specifies which file to read; it must be of the form
'ID/NAME', where ID specifies an SPU context ID in the target
process, and NAME identifes the 'spufs' file in that context
to be accessed.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:threads:read::OFFSET,LENGTH'
Access the list of threads on target. Thread List
Format. The annex part of the generic 'qXfer' packet must
be empty (qXfer read).

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:traceframe-info:read::OFFSET,LENGTH'

Return a description of the current traceframe's contents.
Traceframe Info Format. The annex part of the generic
'qXfer' packet must be empty (qXfer read).

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:uib:read:PC:OFFSET,LENGTH'

Return the unwind information block for PC. This packet is
used on OpenVMS/ia64 to ask the kernel unwind information.

This packet is not probed by default.

'qXfer:fdpic:read:ANNEX:OFFSET,LENGTH'
Read contents of 'loadmap's on the target system. The annex,
either 'exec' or 'interp', specifies which 'loadmap',
executable 'loadmap' or interpreter 'loadmap' to read.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:osdata:read::OFFSET,LENGTH'
Access the target's "operating system information".
Operating System Information.

'qXfer:OBJECT:write:ANNEX:OFFSET:DATA...'
Write uninterpreted bytes into the target's special data area
identified by the keyword OBJECT, starting at OFFSET bytes into the
data. The binary-encoded data (Binary Data) to be written
is given by DATA.... The content and encoding of ANNEX is specific
to OBJECT; it can supply additional details about what data to
access.

Reply:
'NN'
NN (hex encoded) is the number of bytes written. This may be
fewer bytes than supplied in the request.

'E00'
The request was malformed, or ANNEX was invalid.

'E NN'
The offset was invalid, or there was an error encountered
writing the data. The NN part is a hex-encoded 'errno' value.

''
An empty reply indicates the OBJECT string was not recognized
by the stub, or that the object does not support writing.

Here are the specific requests of this form defined so far. All
the 'qXfer:OBJECT:write:...' requests use the same reply formats,
listed above.

'qXfer:siginfo:write::OFFSET:DATA...'
Write DATA to the extra signal information on the target
system. The annex part of the generic 'qXfer' packet must be
empty (qXfer write).

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:spu:write:ANNEX:OFFSET:DATA...'
Write DATA to an 'spufs' file on the target system. The annex
specifies which file to write; it must be of the form
'ID/NAME', where ID specifies an SPU context ID in the target
process, and NAME identifes the 'spufs' file in that context
to be accessed.

This packet is not probed by default; the remote stub must
request it, by supplying an appropriate 'qSupported' response
(qSupported).

'qXfer:OBJECT:OPERATION:...'
Requests of this form may be added in the future. When a stub does
not recognize the OBJECT keyword, or its support for OBJECT does
not recognize the OPERATION keyword, the stub must respond with an
empty packet.

'qAttached:PID'
Return an indication of whether the remote server attached to an
existing process or created a new process. When the multiprocess
protocol extensions are supported (multiprocess
extensions), PID is an integer in hexadecimal format identifying
the target process. Otherwise, GDB will omit the PID field and the
query packet will be simplified as 'qAttached'.

This query is used, for example, to know whether the remote process
should be detached or killed when a GDB session is ended with the
'quit' command.

Reply:
'1'
The remote server attached to an existing process.
'0'
The remote server created a new process.
'E NN'
A badly formed request or an error was encountered.

'Qbtrace:bts'
Enable branch tracing for the current thread using Branch Trace
Store.

Reply:
'OK'
Branch tracing has been enabled.
'E.errtext'
A badly formed request or an error was encountered.

'Qbtrace:pt'
Enable branch tracing for the current thread using Intel Processor
Trace.

Reply:
'OK'
Branch tracing has been enabled.
'E.errtext'
A badly formed request or an error was encountered.

'Qbtrace:off'
Disable branch tracing for the current thread.

Reply:
'OK'
Branch tracing has been disabled.
'E.errtext'
A badly formed request or an error was encountered.

'Qbtrace-conf:bts:size=VALUE'
Set the requested ring buffer size for new threads that use the
btrace recording method in bts format.

Reply:
'OK'
The ring buffer size has been set.
'E.errtext'
A badly formed request or an error was encountered.

'Qbtrace-conf:pt:size=VALUE'
Set the requested ring buffer size for new threads that use the
btrace recording method in pt format.

Reply:
'OK'
The ring buffer size has been set.
'E.errtext'
A badly formed request or an error was encountered.

---------- Footnotes ----------

(1) The 'qP' and 'qL' packets predate these conventions, and have
arguments without any terminator for the packet name; we suspect they
are in widespread use in places that are difficult to upgrade. The 'qC'
packet has no arguments, but some existing stubs (e.g. RedBoot) are
known to not check for the end of the packet.

Info Catalog

gdb: Stop Reply Packets

gdb: Remote Protocol

gdb: Architecture-Specific Protocol Details