2. The Usb Version Of The Gbd Files
Next:, Up: 20.1 Connecting to a Remote TargetThis section describes how to connect to a remote target, including thetypes of connections and their differences, how to set up executable andsymbol files on the host and target, and the commands used forconnecting to and disconnecting from the remote target.20.1.1 Types of Remote ConnectionsGDB supports two types of remote connections, target remotemode and target extended-remote mode. Note that many remote targetssupport only target remote mode.
There are several majordifferences between the two types of connections, enumerated here:Result of detach or program exitWith target remote mode: When the debugged program exits or youdetach from it, GDB disconnects from the target. When usinggdbserver, gdbserver will exit.With target extended-remote mode: When the debugged program exits oryou detach from it, GDB remains connected to the target, eventhough no program is running. You can rerun the program, attach to arunning program, or use monitor commands specific to the target.When using gdbserver in this case, it does not exit unless it wasinvoked using the -once option.
If the -once optionwas not used, you can ask gdbserver to exit using themonitor exit command (see ).Specifying the program to debugFor both connection types you use the file command to specify theprogram on the host system. If you are using gdbserver there aresome differences in how to specify the location of the program on thetarget.With target remote mode: You must either specify the program to debugon the gdbserver command line or use the -attach option(see ).With target extended-remote mode: You may specify the program to debugon the gdbserver command line, or you can load the program or attachto it using GDB commands after connecting to gdbserver.You can start gdbserver without supplying an initial command to runor process ID to attach. To do this, use the -multi command lineoption. Then you can connect using target extended-remote and startthe program you want to debug (see below for details on using therun command in this scenario). Note that the conditions under whichgdbserver terminates depend on how GDB connects to it( target remote or target extended-remote).
The-multi option to gdbserver has no influence on that.The run commandWith target remote mode: The run command is notsupported. Once a connection has been established, you can use allthe usual GDB commands to examine and change data.
Theremote program is already running, so you can use commands likestep and continue.With target extended-remote mode: The run command issupported. The run command uses the value set byset remote exec-file (see ) to selectthe program to run.
Command line arguments are supported, except forwildcard expansion and I/O redirection (see ).If you specify the program to debug on the command line, then therun command is not required to start execution, and you canresume using commands like step and continue as withtarget remote mode.AttachingWith target remote mode: The GDB command attach isnot supported. To attach to a running program using gdbserver, youmust use the -attach option (see ).With target extended-remote mode: To attach to a running program,you may use the attach command after the connection has beenestablished. If you are using gdbserver, you may also invokegdbserver using the -attach option(see ).20.1.2 Host and Target FilesGDB, running on the host, needs access to symbol and debugginginformation for your program running on the target.
This requiresaccess to an unstripped copy of your program, and possibly any associatedsymbol files. Note that this section applies equally to both targetremote mode and target extended-remote mode.Some remote targets (see, andsee ) allow GDB to access program files overthe same connection used to communicate with GDB. With such atarget, if the remote program is unstripped, the only command you need istarget remote (or target extended-remote).If the remote program is stripped, or the target does not support remoteprogram file access, start up GDB using the name of the localunstripped copy of your program as the first argument, or use thefile command.
Use set sysroot to specify the location (onthe host) of target libraries (unless your GDB was compiled withthe correct sysroot using -with-sysroot). Alternatively, youmay use set solib-search-path to specify how GDB locatestarget libraries.The symbol file and target libraries must exactly match the executableand libraries on the target, with one exception: the files on the hostsystem should not be stripped, even if the files on the target systemare. Mismatched or missing files will lead to confusing resultsduring debugging. On GNU/Linux targets, mismatched or missingfiles may also prevent gdbserver from debugging multi-threadedprograms.20.1.3 Remote Connection CommandsGDB can communicate with the target over a serial line, alocal Unix domain socket, orover an IP network using TCP or UDP. Ineach case, GDB uses the same protocol for debugging yourprogram; only the medium carrying the debugging packets varies. Thetarget remote and target extended-remote commandsestablish a connection to the target.
Both commands accept the samearguments, which indicate the medium to use:target remote serial-device target extended-remote serial-deviceUse serial-device to communicate with the target. For example,to use a serial line connected to the device named /dev/ttyb.
Target remote /tmp/gdb-socket0Note that this command has the same form as the command to connectto a serial line. Target remote tcp6:2001:0db8:85a3:0000:0000:8a2e:0370:7334:2828This last example may be confusing to the reader, because there is novisible separation between the hostname and the port number.Therefore, we recommend the user to provide IPv6 addressesusing square brackets for clarity.
However, it is important tomention that for GDB there is no ambiguity: the number afterthe last colon is considered to be the port number.If your remote target is actually running on the same machine as yourdebugger session (e.g. A simulator for your target running on thesame host), you can omit the hostname.
For example, to connect toport 1234 on your local machine. Target remote:1234Note that the colon is still required here.target remote udp: host: port target remote udp: host: port target remote udp4: host: port target remote udp6: host: port target extended-remote udp: host: port target extended-remote udp: host: port target extended-remote udp: host: port target extended-remote udp4: host: port target extended-remote udp6: host: port target extended-remote udp6: host: portDebug using UDP packets to port on host. For example, toconnect to UDP port 2828 on a terminal server named manyfarms. Target remote udp:manyfarms:2828When using a UDP connection for remote debugging, you shouldkeep in mind that the ‘U’ stands for “Unreliable”.
UDPcan silently drop packets on busy or unreliable networks, which willcause havoc with your debugging session.target remote command target extended-remote commandRun command in the background and communicate with it using apipe. The command is a shell command, to be parsed and expandedby the system’s command shell, /bin/sh; it should expect remoteprotocol packets on its standard input, and send replies on itsstandard output. You could use this to run a stand-alone simulatorthat speaks the remote debugging protocol, to make net connectionsusing programs like ssh, or for other similar tricks.If command closes its standard output (perhaps by exiting),GDB will try to send it a SIGTERM signal. (If theprogram has already exited, this will have no effect.)Whenever GDB is waiting for the remote program, if you type theinterrupt character (often Ctrl-c), GDB attempts to stop theprogram. This may or may not succeed, depending in part on the hardwareand the serial drivers the remote system uses.
2. The Usb Version Of The Gbd Files Pdf
If you type theinterrupt character once again, GDB displays this prompt. Interrupted while waiting for the program.Give up (and stop debugging it)? (y or n)In target remote mode, if you type y, GDB abandonsthe remote debugging session. (If you decide you want to try again later,you can use target remote again to connect once more.) If you typen, GDB goes back to waiting.In target extended-remote mode, typing n will leaveGDB connected to the target.detachWhen you have finished debugging the remote program, you can use thedetach command to release it from GDB control.Detaching from the target normally resumes its execution, but the resultswill depend on your particular remote stub. After the detachcommand in target remote mode, GDB is free to connect toanother target.
2. The Usb Version Of The Gbd Files Download
In target extended-remote mode, GDB isstill connected to the target.disconnectThe disconnect command closes the connection to the target, andthe target is generally not resumed. It will wait for GDB(this instance or another one) to connect and continue debugging. Afterthe disconnect command, GDB is again free to connect toanother target.monitor cmdThis command allows you to send arbitrary commands directly to theremote monitor. Since GDB doesn’t care about the commands itsends like this, this command is the way to extend GDB—youcan add new commands that only the external monitor will understandand implement.