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| <h4 class="subsection">21.4.4 MIPS</h4> |
| |
| <p><a name="index-stack-on-Alpha-1401"></a><a name="index-stack-on-MIPS-1402"></a><a name="index-Alpha-stack-1403"></a><a name="index-MIPS-stack-1404"></a>Alpha- and MIPS-based computers use an unusual stack frame, which |
| sometimes requires <span class="sc">gdb</span> to search backward in the object code to |
| find the beginning of a function. |
| |
| <p><a name="index-response-time_002c-MIPS-debugging-1405"></a>To improve response time (especially for embedded applications, where |
| <span class="sc">gdb</span> may be restricted to a slow serial line for this search) |
| you may want to limit the size of this search, using one of these |
| commands: |
| |
| |
| <a name="index-g_t_0040code_007bheuristic_002dfence_002dpost_007d-_0028Alpha_002c-MIPS_0029-1406"></a> |
| <dl><dt><code>set heuristic-fence-post </code><var>limit</var><dd>Restrict <span class="sc">gdb</span> to examining at most <var>limit</var> bytes in its |
| search for the beginning of a function. A value of <var>0</var> (the |
| default) means there is no limit. However, except for <var>0</var>, the |
| larger the limit the more bytes <code>heuristic-fence-post</code> must search |
| and therefore the longer it takes to run. You should only need to use |
| this command when debugging a stripped executable. |
| |
| <br><dt><code>show heuristic-fence-post</code><dd>Display the current limit. |
| </dl> |
| |
| <p class="noindent">These commands are available <em>only</em> when <span class="sc">gdb</span> is configured |
| for debugging programs on Alpha or MIPS processors. |
| |
| <p>Several MIPS-specific commands are available when debugging MIPS |
| programs: |
| |
| <dl> |
| <dt><code>set mips abi </code><var>arg</var><dd><a name="index-set-mips-abi-1407"></a><a name="index-set-ABI-for-MIPS-1408"></a>Tell <span class="sc">gdb</span> which MIPS ABI is used by the inferior. Possible |
| values of <var>arg</var> are: |
| |
| <dl> |
| <dt>‘<samp><span class="samp">auto</span></samp>’<dd>The default ABI associated with the current binary (this is the |
| default). |
| <br><dt>‘<samp><span class="samp">o32</span></samp>’<br><dt>‘<samp><span class="samp">o64</span></samp>’<br><dt>‘<samp><span class="samp">n32</span></samp>’<br><dt>‘<samp><span class="samp">n64</span></samp>’<br><dt>‘<samp><span class="samp">eabi32</span></samp>’<br><dt>‘<samp><span class="samp">eabi64</span></samp>’<dd></dl> |
| |
| <br><dt><code>show mips abi</code><dd><a name="index-show-mips-abi-1409"></a>Show the MIPS ABI used by <span class="sc">gdb</span> to debug the inferior. |
| |
| <br><dt><code>set mips compression </code><var>arg</var><dd><a name="index-set-mips-compression-1410"></a><a name="index-MIPS-code-compression-1411"></a>Tell <span class="sc">gdb</span> which MIPS compressed ISA encoding is used by the |
| inferior. <span class="sc">gdb</span> uses this for code disassembly and other |
| internal interpretation purposes. This setting is only referred to |
| when no executable has been associated with the debugging session or |
| the executable does not provide information about the encoding it uses. |
| Otherwise this setting is automatically updated from information |
| provided by the executable. |
| |
| <p>Possible values of <var>arg</var> are ‘<samp><span class="samp">mips16</span></samp>’ and ‘<samp><span class="samp">micromips</span></samp>’. |
| The default compressed ISA encoding is ‘<samp><span class="samp">mips16</span></samp>’, as executables |
| containing MIPS16 code frequently are not identified as such. |
| |
| <p>This setting is “sticky”; that is, it retains its value across |
| debugging sessions until reset either explicitly with this command or |
| implicitly from an executable. |
| |
| <p>The compiler and/or assembler typically add symbol table annotations to |
| identify functions compiled for the MIPS16 or microMIPS ISAs. If these |
| function-scope annotations are present, <span class="sc">gdb</span> uses them in |
| preference to the global compressed ISA encoding setting. |
| |
| <br><dt><code>show mips compression</code><dd><a name="index-show-mips-compression-1412"></a>Show the MIPS compressed ISA encoding used by <span class="sc">gdb</span> to debug the |
| inferior. |
| |
| <br><dt><code>set mipsfpu</code><dt><code>show mipsfpu</code><dd>See <a href="MIPS-Embedded.html#MIPS-Embedded">set mipsfpu</a>. |
| |
| <br><dt><code>set mips mask-address </code><var>arg</var><dd><a name="index-set-mips-mask_002daddress-1413"></a><a name="index-MIPS-addresses_002c-masking-1414"></a>This command determines whether the most-significant 32 bits of 64-bit |
| MIPS addresses are masked off. The argument <var>arg</var> can be |
| ‘<samp><span class="samp">on</span></samp>’, ‘<samp><span class="samp">off</span></samp>’, or ‘<samp><span class="samp">auto</span></samp>’. The latter is the default |
| setting, which lets <span class="sc">gdb</span> determine the correct value. |
| |
| <br><dt><code>show mips mask-address</code><dd><a name="index-show-mips-mask_002daddress-1415"></a>Show whether the upper 32 bits of MIPS addresses are masked off or |
| not. |
| |
| <br><dt><code>set remote-mips64-transfers-32bit-regs</code><dd><a name="index-set-remote_002dmips64_002dtransfers_002d32bit_002dregs-1416"></a>This command controls compatibility with 64-bit MIPS targets that |
| transfer data in 32-bit quantities. If you have an old MIPS 64 target |
| that transfers 32 bits for some registers, like <span class="sc">sr</span> and <span class="sc">fsr</span>, |
| and 64 bits for other registers, set this option to ‘<samp><span class="samp">on</span></samp>’. |
| |
| <br><dt><code>show remote-mips64-transfers-32bit-regs</code><dd><a name="index-show-remote_002dmips64_002dtransfers_002d32bit_002dregs-1417"></a>Show the current setting of compatibility with older MIPS 64 targets. |
| |
| <br><dt><code>set debug mips</code><dd><a name="index-set-debug-mips-1418"></a>This command turns on and off debugging messages for the MIPS-specific |
| target code in <span class="sc">gdb</span>. |
| |
| <br><dt><code>show debug mips</code><dd><a name="index-show-debug-mips-1419"></a>Show the current setting of MIPS debugging messages. |
| </dl> |
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