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192 lines
10 KiB
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<html lang="en">
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<head>
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<title>Target Commands - Debugging with GDB</title>
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<meta http-equiv="Content-Type" content="text/html">
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<meta name="description" content="Debugging with GDB">
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<meta name="generator" content="makeinfo 4.13">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Targets.html#Targets" title="Targets">
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<link rel="prev" href="Active-Targets.html#Active-Targets" title="Active Targets">
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<link rel="next" href="Byte-Order.html#Byte-Order" title="Byte Order">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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Copyright (C) 1988-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being ``Free Software'' and ``Free Software Needs
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Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
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this GNU Manual. Buying copies from GNU Press supports the FSF in
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--></style>
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</head>
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<body>
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<div class="node">
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<a name="Target-Commands"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Byte-Order.html#Byte-Order">Byte Order</a>,
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Previous: <a rel="previous" accesskey="p" href="Active-Targets.html#Active-Targets">Active Targets</a>,
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Up: <a rel="up" accesskey="u" href="Targets.html#Targets">Targets</a>
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<hr>
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</div>
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<h3 class="section">19.2 Commands for Managing Targets</h3>
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<dl>
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<dt><code>target </code><var>type</var> <var>parameters</var><dd>Connects the <span class="sc">gdb</span> host environment to a target machine or
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process. A target is typically a protocol for talking to debugging
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facilities. You use the argument <var>type</var> to specify the type or
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protocol of the target machine.
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<p>Further <var>parameters</var> are interpreted by the target protocol, but
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typically include things like device names or host names to connect
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with, process numbers, and baud rates.
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<p>The <code>target</code> command does not repeat if you press <RET> again
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after executing the command.
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<p><a name="index-help-target-1310"></a><br><dt><code>help target</code><dd>Displays the names of all targets available. To display targets
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currently selected, use either <code>info target</code> or <code>info files</code>
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(see <a href="Files.html#Files">Commands to Specify Files</a>).
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<br><dt><code>help target </code><var>name</var><dd>Describe a particular target, including any parameters necessary to
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select it.
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<p><a name="index-set-gnutarget-1311"></a><br><dt><code>set gnutarget </code><var>args</var><dd><span class="sc">gdb</span> uses its own library BFD to read your files. <span class="sc">gdb</span>
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knows whether it is reading an <dfn>executable</dfn>,
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a <dfn>core</dfn>, or a <dfn>.o</dfn> file; however, you can specify the file format
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with the <code>set gnutarget</code> command. Unlike most <code>target</code> commands,
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with <code>gnutarget</code> the <code>target</code> refers to a program, not a machine.
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<blockquote>
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<em>Warning:</em> To specify a file format with <code>set gnutarget</code>,
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you must know the actual BFD name.
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</blockquote>
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<p class="noindent">See <a href="Files.html#Files">Commands to Specify Files</a>.
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<p><a name="index-show-gnutarget-1312"></a><br><dt><code>show gnutarget</code><dd>Use the <code>show gnutarget</code> command to display what file format
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<code>gnutarget</code> is set to read. If you have not set <code>gnutarget</code>,
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<span class="sc">gdb</span> will determine the file format for each file automatically,
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and <code>show gnutarget</code> displays ‘<samp><span class="samp">The current BFD target is "auto"</span></samp>’.
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</dl>
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<p><a name="index-common-targets-1313"></a>Here are some common targets (available, or not, depending on the GDB
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configuration):
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<a name="index-target-1314"></a>
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<dl><dt><code>target exec </code><var>program</var><dd><a name="index-executable-file-target-1315"></a>An executable file. ‘<samp><span class="samp">target exec </span><var>program</var></samp>’ is the same as
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‘<samp><span class="samp">exec-file </span><var>program</var></samp>’.
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<br><dt><code>target core </code><var>filename</var><dd><a name="index-core-dump-file-target-1316"></a>A core dump file. ‘<samp><span class="samp">target core </span><var>filename</var></samp>’ is the same as
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‘<samp><span class="samp">core-file </span><var>filename</var></samp>’.
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<br><dt><code>target remote </code><var>medium</var><dd><a name="index-remote-target-1317"></a>A remote system connected to <span class="sc">gdb</span> via a serial line or network
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connection. This command tells <span class="sc">gdb</span> to use its own remote
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protocol over <var>medium</var> for debugging. See <a href="Remote-Debugging.html#Remote-Debugging">Remote Debugging</a>.
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<p>For example, if you have a board connected to <samp><span class="file">/dev/ttya</span></samp> on the
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machine running <span class="sc">gdb</span>, you could say:
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<pre class="smallexample"> target remote /dev/ttya
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</pre>
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<p><code>target remote</code> supports the <code>load</code> command. This is only
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useful if you have some other way of getting the stub to the target
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system, and you can put it somewhere in memory where it won't get
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clobbered by the download.
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<br><dt><code>target sim </code><span class="roman">[</span><var>simargs</var><span class="roman">]</span><code> ...</code><dd><a name="index-built_002din-simulator-target-1318"></a>Builtin CPU simulator. <span class="sc">gdb</span> includes simulators for most architectures.
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In general,
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<pre class="smallexample"> target sim
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load
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run
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</pre>
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<p class="noindent">works; however, you cannot assume that a specific memory map, device
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drivers, or even basic I/O is available, although some simulators do
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provide these. For info about any processor-specific simulator details,
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see the appropriate section in <a href="Embedded-Processors.html#Embedded-Processors">Embedded Processors</a>.
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<br><dt><code>target native</code><dd><a name="index-native-target-1319"></a>Setup for local/native process debugging. Useful to make the
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<code>run</code> command spawn native processes (likewise <code>attach</code>,
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etc.) even when <code>set auto-connect-native-target</code> is <code>off</code>
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(see <a href="set-auto_002dconnect_002dnative_002dtarget.html#set-auto_002dconnect_002dnative_002dtarget">set auto-connect-native-target</a>).
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</dl>
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<p>Different targets are available on different configurations of <span class="sc">gdb</span>;
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your configuration may have more or fewer targets.
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<p>Many remote targets require you to download the executable's code once
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you've successfully established a connection. You may wish to control
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various aspects of this process.
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<dl>
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<dt><code>set hash</code><dd><a name="index-set-hash_0040r_007b_002c-for-remote-monitors_007d-1320"></a><a name="index-hash-mark-while-downloading-1321"></a>This command controls whether a hash mark ‘<samp><span class="samp">#</span></samp>’ is displayed while
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downloading a file to the remote monitor. If on, a hash mark is
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displayed after each S-record is successfully downloaded to the
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monitor.
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<br><dt><code>show hash</code><dd><a name="index-show-hash_0040r_007b_002c-for-remote-monitors_007d-1322"></a>Show the current status of displaying the hash mark.
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<br><dt><code>set debug monitor</code><dd><a name="index-set-debug-monitor-1323"></a><a name="index-display-remote-monitor-communications-1324"></a>Enable or disable display of communications messages between
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<span class="sc">gdb</span> and the remote monitor.
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<br><dt><code>show debug monitor</code><dd><a name="index-show-debug-monitor-1325"></a>Show the current status of displaying communications between
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<span class="sc">gdb</span> and the remote monitor.
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</dl>
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<a name="index-load-_0040var_007bfilename_007d-_0040var_007boffset_007d-1326"></a>
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<dl><dt><code>load </code><var>filename</var> <var>offset</var><dd><a name="load"></a>Depending on what remote debugging facilities are configured into
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<span class="sc">gdb</span>, the <code>load</code> command may be available. Where it exists, it
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is meant to make <var>filename</var> (an executable) available for debugging
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on the remote system—by downloading, or dynamic linking, for example.
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<code>load</code> also records the <var>filename</var> symbol table in <span class="sc">gdb</span>, like
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the <code>add-symbol-file</code> command.
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<p>If your <span class="sc">gdb</span> does not have a <code>load</code> command, attempting to
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execute it gets the error message “<code>You can't do that when your
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target is ...</code>”
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<p>The file is loaded at whatever address is specified in the executable.
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For some object file formats, you can specify the load address when you
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link the program; for other formats, like a.out, the object file format
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specifies a fixed address.
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<!-- FIXME! This would be a good place for an xref to the GNU linker doc. -->
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<p>It is also possible to tell <span class="sc">gdb</span> to load the executable file at a
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specific offset described by the optional argument <var>offset</var>. When
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<var>offset</var> is provided, <var>filename</var> must also be provided.
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<p>Depending on the remote side capabilities, <span class="sc">gdb</span> may be able to
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load programs into flash memory.
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<p><code>load</code> does not repeat if you press <RET> again after using it.
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</dl>
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<a name="index-flash_002derase-1327"></a>
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<dl><dt><code>flash-erase</code><dd><a name="flash_002derase"></a>Erases all known flash memory regions on the target.
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</dl>
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</body></html>
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