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| |
| <h3 class="section">27.23 <span class="sc">gdb/mi</span> Support Commands</h3> |
| |
| <p>Since new commands and features get regularly added to <span class="sc">gdb/mi</span>, |
| some commands are available to help front-ends query the debugger |
| about support for these capabilities. Similarly, it is also possible |
| to query <span class="sc">gdb</span> about target support of certain features. |
| |
| <h4 class="subheading">The <code>-info-gdb-mi-command</code> Command</h4> |
| |
| <p><a name="index-g_t_0040code_007b_002dinfo_002dgdb_002dmi_002dcommand_007d-3081"></a><a name="index-g_t_002dinfo_002dgdb_002dmi_002dcommand-3082"></a> |
| |
| <h5 class="subsubheading">Synopsis</h5> |
| |
| <pre class="smallexample"> -info-gdb-mi-command <var>cmd_name</var> |
| </pre> |
| <p>Query support for the <span class="sc">gdb/mi</span> command named <var>cmd_name</var>. |
| |
| <p>Note that the dash (<code>-</code>) starting all <span class="sc">gdb/mi</span> commands |
| is technically not part of the command name (see <a href="GDB_002fMI-Input-Syntax.html#GDB_002fMI-Input-Syntax">GDB/MI Input Syntax</a>), and thus should be omitted in <var>cmd_name</var>. However, |
| for ease of use, this command also accepts the form with the leading |
| dash. |
| |
| <h5 class="subsubheading"><span class="sc">gdb</span> Command</h5> |
| |
| <p>There is no corresponding <span class="sc">gdb</span> command. |
| |
| <h5 class="subsubheading">Result</h5> |
| |
| <p>The result is a tuple. There is currently only one field: |
| |
| <dl> |
| <dt>‘<samp><span class="samp">exists</span></samp>’<dd>This field is equal to <code>"true"</code> if the <span class="sc">gdb/mi</span> command exists, |
| <code>"false"</code> otherwise. |
| |
| </dl> |
| |
| <h5 class="subsubheading">Example</h5> |
| |
| <p>Here is an example where the <span class="sc">gdb/mi</span> command does not exist: |
| |
| <pre class="smallexample"> -info-gdb-mi-command unsupported-command |
| ^done,command={exists="false"} |
| </pre> |
| <p class="noindent">And here is an example where the <span class="sc">gdb/mi</span> command is known |
| to the debugger: |
| |
| <pre class="smallexample"> -info-gdb-mi-command symbol-list-lines |
| ^done,command={exists="true"} |
| </pre> |
| <h4 class="subheading">The <code>-list-features</code> Command</h4> |
| |
| <p><a name="index-g_t_002dlist_002dfeatures-3083"></a><a name="index-supported-_0040sc_007bgdb_002fmi_007d-features_002c-list-3084"></a> |
| Returns a list of particular features of the MI protocol that |
| this version of gdb implements. A feature can be a command, |
| or a new field in an output of some command, or even an |
| important bugfix. While a frontend can sometimes detect presence |
| of a feature at runtime, it is easier to perform detection at debugger |
| startup. |
| |
| <p>The command returns a list of strings, with each string naming an |
| available feature. Each returned string is just a name, it does not |
| have any internal structure. The list of possible feature names |
| is given below. |
| |
| <p>Example output: |
| |
| <pre class="smallexample"> (gdb) -list-features |
| ^done,result=["feature1","feature2"] |
| </pre> |
| <p>The current list of features is: |
| |
| <dl> |
| <dt>‘<samp><span class="samp">frozen-varobjs</span></samp>’<a name="index-frozen_002dvarobjs-3085"></a><dd>Indicates support for the <code>-var-set-frozen</code> command, as well |
| as possible presense of the <code>frozen</code> field in the output |
| of <code>-varobj-create</code>. |
| <br><dt>‘<samp><span class="samp">pending-breakpoints</span></samp>’<a name="index-pending_002dbreakpoints-3086"></a><dd>Indicates support for the <samp><span class="option">-f</span></samp> option to the <code>-break-insert</code> |
| command. |
| <br><dt>‘<samp><span class="samp">python</span></samp>’<a name="index-python-3087"></a><dd>Indicates Python scripting support, Python-based |
| pretty-printing commands, and possible presence of the |
| ‘<samp><span class="samp">display_hint</span></samp>’ field in the output of <code>-var-list-children</code> |
| <br><dt>‘<samp><span class="samp">thread-info</span></samp>’<a name="index-thread_002dinfo-3088"></a><dd>Indicates support for the <code>-thread-info</code> command. |
| <br><dt>‘<samp><span class="samp">data-read-memory-bytes</span></samp>’<a name="index-data_002dread_002dmemory_002dbytes-3089"></a><dd>Indicates support for the <code>-data-read-memory-bytes</code> and the |
| <code>-data-write-memory-bytes</code> commands. |
| <br><dt>‘<samp><span class="samp">breakpoint-notifications</span></samp>’<a name="index-breakpoint_002dnotifications-3090"></a><dd>Indicates that changes to breakpoints and breakpoints created via the |
| CLI will be announced via async records. |
| <br><dt>‘<samp><span class="samp">ada-task-info</span></samp>’<a name="index-ada_002dtask_002dinfo-3091"></a><dd>Indicates support for the <code>-ada-task-info</code> command. |
| <br><dt>‘<samp><span class="samp">language-option</span></samp>’<a name="index-language_002doption-3092"></a><dd>Indicates that all <span class="sc">gdb/mi</span> commands accept the <samp><span class="option">--language</span></samp> |
| option (see <a href="Context-management.html#Context-management">Context management</a>). |
| <br><dt>‘<samp><span class="samp">info-gdb-mi-command</span></samp>’<a name="index-info_002dgdb_002dmi_002dcommand-3093"></a><dd>Indicates support for the <code>-info-gdb-mi-command</code> command. |
| <br><dt>‘<samp><span class="samp">undefined-command-error-code</span></samp>’<a name="index-undefined_002dcommand_002derror_002dcode-3094"></a><dd>Indicates support for the "undefined-command" error code in error result |
| records, produced when trying to execute an undefined <span class="sc">gdb/mi</span> command |
| (see <a href="GDB_002fMI-Result-Records.html#GDB_002fMI-Result-Records">GDB/MI Result Records</a>). |
| <br><dt>‘<samp><span class="samp">exec-run-start-option</span></samp>’<a name="index-exec_002drun_002dstart_002doption-3095"></a><dd>Indicates that the <code>-exec-run</code> command supports the <samp><span class="option">--start</span></samp> |
| option (see <a href="GDB_002fMI-Program-Execution.html#GDB_002fMI-Program-Execution">GDB/MI Program Execution</a>). |
| <br><dt>‘<samp><span class="samp">data-disassemble-a-option</span></samp>’<a name="index-data_002ddisassemble_002da_002doption-3096"></a><dd>Indicates that the <code>-data-disassemble</code> command supports the <samp><span class="option">-a</span></samp> |
| option (see <a href="GDB_002fMI-Data-Manipulation.html#GDB_002fMI-Data-Manipulation">GDB/MI Data Manipulation</a>). |
| </dl> |
| |
| <h4 class="subheading">The <code>-list-target-features</code> Command</h4> |
| |
| <p><a name="index-g_t_002dlist_002dtarget_002dfeatures-3097"></a> |
| Returns a list of particular features that are supported by the |
| target. Those features affect the permitted MI commands, but |
| unlike the features reported by the <code>-list-features</code> command, the |
| features depend on which target GDB is using at the moment. Whenever |
| a target can change, due to commands such as <code>-target-select</code>, |
| <code>-target-attach</code> or <code>-exec-run</code>, the list of target features |
| may change, and the frontend should obtain it again. |
| Example output: |
| |
| <pre class="smallexample"> (gdb) -list-target-features |
| ^done,result=["async"] |
| </pre> |
| <p>The current list of features is: |
| |
| <dl> |
| <dt>‘<samp><span class="samp">async</span></samp>’<dd>Indicates that the target is capable of asynchronous command |
| execution, which means that <span class="sc">gdb</span> will accept further commands |
| while the target is running. |
| |
| <br><dt>‘<samp><span class="samp">reverse</span></samp>’<dd>Indicates that the target is capable of reverse execution. |
| See <a href="Reverse-Execution.html#Reverse-Execution">Reverse Execution</a>, for more information. |
| |
| </dl> |
| |
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