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20.4 Remote Configuration

This section documents the configuration options available when debugging remote programs. For the options related to the File I/O extensions of the remote protocol, see system-call-allowed.

set remoteaddresssize bits
Set the maximum size of address in a memory packet to the specified number of bits. gdb will mask off the address bits above that number, when it passes addresses to the remote target. The default value is the number of bits in the target's address.
show remoteaddresssize
Show the current value of remote address size in bits.
set serial baud n
Set the baud rate for the remote serial I/O to n baud. The value is used to set the speed of the serial port used for debugging remote targets.
show serial baud
Show the current speed of the remote connection.
set serial parity parity
Set the parity for the remote serial I/O. Supported values of parity are: even, none, and odd. The default is none.
show serial parity
Show the current parity of the serial port.
set remotebreak
If set to on, gdb sends a BREAK signal to the remote when you type Ctrl-c to interrupt the program running on the remote. If set to off, gdb sends the ‘Ctrl-C’ character instead. The default is off, since most remote systems expect to see ‘Ctrl-C’ as the interrupt signal.
show remotebreak
Show whether gdb sends BREAK or ‘Ctrl-C’ to interrupt the remote program.
set remoteflow on
set remoteflow off
Enable or disable hardware flow control (RTS/CTS) on the serial port used to communicate to the remote target.
show remoteflow
Show the current setting of hardware flow control.
set remotelogbase base
Set the base (a.k.a. radix) of logging serial protocol communications to base. Supported values of base are: ascii, octal, and hex. The default is ascii.
show remotelogbase
Show the current setting of the radix for logging remote serial protocol.
set remotelogfile file
Record remote serial communications on the named file. The default is not to record at all.
show remotelogfile.
Show the current setting of the file name on which to record the serial communications.
set remotetimeout num
Set the timeout limit to wait for the remote target to respond to num seconds. The default is 2 seconds.
show remotetimeout
Show the current number of seconds to wait for the remote target responses.


set remote hardware-watchpoint-limit limit
set remote hardware-breakpoint-limit limit
Restrict gdb to using limit remote hardware breakpoint or watchpoints. A limit of -1, the default, is treated as unlimited.


set remote hardware-watchpoint-length-limit limit
Restrict gdb to using limit bytes for the maximum length of a remote hardware watchpoint. A limit of -1, the default, is treated as unlimited.
show remote hardware-watchpoint-length-limit
Show the current limit (in bytes) of the maximum length of a remote hardware watchpoint.
set remote exec-file filename
show remote exec-file
Select the file used for run with target extended-remote. This should be set to a filename valid on the target system. If it is not set, the target will use a default filename (e.g. the last program run).
set remote interrupt-sequence
Allow the user to select one of ‘Ctrl-C’, a BREAK or ‘BREAK-g’ as the sequence to the remote target in order to interrupt the execution. ‘Ctrl-C’ is a default. Some system prefers BREAK which is high level of serial line for some certain time. Linux kernel prefers ‘BREAK-g’, a.k.a Magic SysRq g. It is BREAK signal followed by character g.
show interrupt-sequence
Show which of ‘Ctrl-C’, BREAK or BREAK-g is sent by gdb to interrupt the remote program. BREAK-g is BREAK signal followed by g and also known as Magic SysRq g.
set remote interrupt-on-connect
Specify whether interrupt-sequence is sent to remote target when gdb connects to it. This is mostly needed when you debug Linux kernel. Linux kernel expects BREAK followed by g which is known as Magic SysRq g in order to connect gdb.
show interrupt-on-connect
Show whether interrupt-sequence is sent to remote target when gdb connects to it.


set tcp auto-retry on
Enable auto-retry for remote TCP connections. This is useful if the remote debugging agent is launched in parallel with gdb; there is a race condition because the agent may not become ready to accept the connection before gdb attempts to connect. When auto-retry is enabled, if the initial attempt to connect fails, gdb reattempts to establish the connection using the timeout specified by set tcp connect-timeout.
set tcp auto-retry off
Do not auto-retry failed TCP connections.
show tcp auto-retry
Show the current auto-retry setting.
set tcp connect-timeout seconds
set tcp connect-timeout unlimited
Set the timeout for establishing a TCP connection to the remote target to seconds. The timeout affects both polling to retry failed connections (enabled by set tcp auto-retry on) and waiting for connections that are merely slow to complete, and represents an approximate cumulative value. If seconds is unlimited, there is no timeout and gdb will keep attempting to establish a connection forever, unless interrupted with Ctrl-c. The default is 15 seconds.
show tcp connect-timeout
Show the current connection timeout setting.

The gdb remote protocol autodetects the packets supported by your debugging stub. If you need to override the autodetection, you can use these commands to enable or disable individual packets. Each packet can be set to ‘on’ (the remote target supports this packet), ‘off’ (the remote target does not support this packet), or ‘auto’ (detect remote target support for this packet). They all default to ‘auto’. For more information about each packet, see Remote Protocol.

During normal use, you should not have to use any of these commands. If you do, that may be a bug in your remote debugging stub, or a bug in gdb. You may want to report the problem to the gdb developers.

For each packet name, the command to enable or disable the packet is set remote name-packet. The available settings are:

Command Name Remote Packet Related Features


fetch-register p info registers


set-register P set


binary-download X load, set


read-aux-vector qXfer:auxv:read info auxv


symbol-lookup qSymbol Detecting multiple threads


attach vAttach attach


verbose-resume vCont Stepping or resuming multiple threads


run vRun run


software-breakpoint Z0 break


hardware-breakpoint Z1 hbreak


write-watchpoint Z2 watch


read-watchpoint Z3 rwatch


access-watchpoint Z4 awatch


pid-to-exec-file qXfer:exec-file:read attach, run


target-features qXfer:features:read set architecture


library-info qXfer:libraries:read info sharedlibrary


memory-map qXfer:memory-map:read info mem


read-sdata-object qXfer:sdata:read print $_sdata


read-spu-object qXfer:spu:read info spu


write-spu-object qXfer:spu:write info spu


read-siginfo-object qXfer:siginfo:read print $_siginfo


write-siginfo-object qXfer:siginfo:write set $_siginfo


threads qXfer:threads:read info threads


get-thread-local-
storage-address
qGetTLSAddr Displaying __thread variables


get-thread-information-block-address qGetTIBAddr Display MS-Windows Thread Information Block.


search-memory qSearch:memory find


supported-packets qSupported Remote communications parameters


pass-signals QPassSignals handle signal


program-signals QProgramSignals handle signal


hostio-close-packet vFile:close remote get, remote put


hostio-open-packet vFile:open remote get, remote put


hostio-pread-packet vFile:pread remote get, remote put


hostio-pwrite-packet vFile:pwrite remote get, remote put


hostio-unlink-packet vFile:unlink remote delete


hostio-readlink-packet vFile:readlink Host I/O


hostio-fstat-packet vFile:fstat Host I/O


noack-packet QStartNoAckMode Packet acknowledgment


osdata qXfer:osdata:read info os


query-attached qAttached Querying remote process attach state.


trace-buffer-size QTBuffer:size set trace-buffer-size


trace-status qTStatus tstatus


traceframe-info qXfer:traceframe-info:read Traceframe info


install-in-trace InstallInTrace Install tracepoint in tracing


disable-randomization QDisableRandomization set disable-randomization


conditional-breakpoints-packet Z0 and Z1 Support for target-side breakpoint condition evaluation


swbreak-feature swbreak stop reason break


hwbreak-feature hwbreak stop reason hbreak


fork-event-feature fork stop reason fork


vfork-event-feature vfork stop reason vfork