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Tracepoint-Packets.html

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    64. 

  64. <a name="Tracepoint-Packets"></a>
    65. 

  65. <div class="header">
    66. 

  66. <p>
    67. 

  67. Next: <a href="Host-I_002fO-Packets.html#Host-I_002fO-Packets" accesskey="n" rel="next">Host I/O Packets</a>, Previous: <a href="Architecture_002dSpecific-Protocol-Details.html#Architecture_002dSpecific-Protocol-Details" accesskey="p" rel="previous">Architecture-Specific Protocol Details</a>, Up: <a href="Remote-Protocol.html#Remote-Protocol" accesskey="u" rel="up">Remote Protocol</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
    68. 

  68. </div>
    69. 

  69. <hr>
    70. 

  70. <a name="Tracepoint-Packets-1"></a>
    71. 

  71. <h3 class="section">E.6 Tracepoint Packets</h3>
    72. 

  72. <a name="index-tracepoint-packets"></a>
    73. 

  73. <a name="index-packets_002c-tracepoint"></a>
    74. 

  74. 

  75. <p>Here we describe the packets <small>GDB</small> uses to implement
    76. 

  76. tracepoints (see <a href="Tracepoints.html#Tracepoints">Tracepoints</a>).
    77. 

  77. </p>
    78. 

  78. <dl compact="compact">
    79. 

  79. <dt>&lsquo;<samp>QTDP:<var>n</var>:<var>addr</var>:<var>ena</var>:<var>step</var>:<var>pass</var>[:F<var>flen</var>][:X<var>len</var>,<var>bytes</var>]<span class="roman">[</span>-<span class="roman">]</span></samp>&rsquo;</dt>
    80. 

  80. <dd><a name="index-QTDP-packet"></a>
    81. 

  81. <p>Create a new tracepoint, number <var>n</var>, at <var>addr</var>.  If <var>ena</var>
    82. 

  82. is &lsquo;<samp>E</samp>&rsquo;, then the tracepoint is enabled; if it is &lsquo;<samp>D</samp>&rsquo;, then
    83. 

  83. the tracepoint is disabled.  The <var>step</var> gives the tracepoint&rsquo;s step
    84. 

  84. count, and <var>pass</var> gives its pass count.  If an &lsquo;<samp>F</samp>&rsquo; is present,
    85. 

  85. then the tracepoint is to be a fast tracepoint, and the <var>flen</var> is
    86. 

  86. the number of bytes that the target should copy elsewhere to make room
    87. 

  87. for the tracepoint.  If an &lsquo;<samp>X</samp>&rsquo; is present, it introduces a
    88. 

  88. tracepoint condition, which consists of a hexadecimal length, followed
    89. 

  89. by a comma and hex-encoded bytes, in a manner similar to action
    90. 

  90. encodings as described below.  If the trailing &lsquo;<samp>-</samp>&rsquo; is present,
    91. 

  91. further &lsquo;<samp>QTDP</samp>&rsquo; packets will follow to specify this tracepoint&rsquo;s
    92. 

  92. actions.
    93. 

  93. </p>
    94. 

  94. <p>Replies:
    95. 

  95. </p><dl compact="compact">
    96. 

  96. <dt>&lsquo;<samp>OK</samp>&rsquo;</dt>
    97. 

  97. <dd><p>The packet was understood and carried out.
    98. 

  98. </p></dd>
    99. 

  99. <dt>&lsquo;<samp>qRelocInsn</samp>&rsquo;</dt>
    100. 

  100. <dd><p>See <a href="#Tracepoint-Packets">Relocate instruction reply packet</a>.
    101. 

  101. </p></dd>
    102. 

  102. <dt>&lsquo;<samp><!-- /@w --></samp>&rsquo;</dt>
    103. 

  103. <dd><p>The packet was not recognized.
    104. 

  104. </p></dd>
    105. 

  105. </dl>
    106. 

  106. 

  107. </dd>
    108. 

  108. <dt>&lsquo;<samp>QTDP:-<var>n</var>:<var>addr</var>:<span class="roman">[</span>S<span class="roman">]</span><var>action</var>&hellip;<span class="roman">[</span>-<span class="roman">]</span></samp>&rsquo;</dt>
    109. 

  109. <dd><p>Define actions to be taken when a tracepoint is hit.  The <var>n</var> and
    110. 

  110. <var>addr</var> must be the same as in the initial &lsquo;<samp>QTDP</samp>&rsquo; packet for
    111. 

  111. this tracepoint.  This packet may only be sent immediately after
    112. 

  112. another &lsquo;<samp>QTDP</samp>&rsquo; packet that ended with a &lsquo;<samp>-</samp>&rsquo;.  If the
    113. 

  113. trailing &lsquo;<samp>-</samp>&rsquo; is present, further &lsquo;<samp>QTDP</samp>&rsquo; packets will follow,
    114. 

  114. specifying more actions for this tracepoint.
    115. 

  115. </p>
    116. 

  116. <p>In the series of action packets for a given tracepoint, at most one
    117. 

  117. can have an &lsquo;<samp>S</samp>&rsquo; before its first <var>action</var>.  If such a packet
    118. 

  118. is sent, it and the following packets define &ldquo;while-stepping&rdquo;
    119. 

  119. actions.  Any prior packets define ordinary actions &mdash; that is, those
    120. 

  120. taken when the tracepoint is first hit.  If no action packet has an
    121. 

  121. &lsquo;<samp>S</samp>&rsquo;, then all the packets in the series specify ordinary
    122. 

  122. tracepoint actions.
    123. 

  123. </p>
    124. 

  124. <p>The &lsquo;<samp><var>action</var>&hellip;</samp>&rsquo; portion of the packet is a series of
    125. 

  125. actions, concatenated without separators.  Each action has one of the
    126. 

  126. following forms:
    127. 

  127. </p>
    128. 

  128. <dl compact="compact">
    129. 

  129. <dt>&lsquo;<samp>R <var>mask</var></samp>&rsquo;</dt>
    130. 

  130. <dd><p>Collect the registers whose bits are set in <var>mask</var>,
    131. 

  131. a hexadecimal number whose <var>i</var>&rsquo;th bit is set if register number
    132. 

  132. <var>i</var> should be collected.  (The least significant bit is numbered
    133. 

  133. zero.)  Note that <var>mask</var> may be any number of digits long; it may
    134. 

  134. not fit in a 32-bit word.
    135. 

  135. </p>
    136. 

  136. </dd>
    137. 

  137. <dt>&lsquo;<samp>M <var>basereg</var>,<var>offset</var>,<var>len</var></samp>&rsquo;</dt>
    138. 

  138. <dd><p>Collect <var>len</var> bytes of memory starting at the address in register
    139. 

  139. number <var>basereg</var>, plus <var>offset</var>.  If <var>basereg</var> is
    140. 

  140. &lsquo;<samp>-1</samp>&rsquo;, then the range has a fixed address: <var>offset</var> is the
    141. 

  141. address of the lowest byte to collect.  The <var>basereg</var>,
    142. 

  142. <var>offset</var>, and <var>len</var> parameters are all unsigned hexadecimal
    143. 

  143. values (the &lsquo;<samp>-1</samp>&rsquo; value for <var>basereg</var> is a special case).
    144. 

  144. </p>
    145. 

  145. </dd>
    146. 

  146. <dt>&lsquo;<samp>X <var>len</var>,<var>expr</var></samp>&rsquo;</dt>
    147. 

  147. <dd><p>Evaluate <var>expr</var>, whose length is <var>len</var>, and collect memory as
    148. 

  148. it directs.  The agent expression <var>expr</var> is as described in
    149. 

  149. <a href="Agent-Expressions.html#Agent-Expressions">Agent Expressions</a>.  Each byte of the expression is encoded as a
    150. 

  150. two-digit hex number in the packet; <var>len</var> is the number of bytes
    151. 

  151. in the expression (and thus one-half the number of hex digits in the
    152. 

  152. packet).
    153. 

  153. </p>
    154. 

  154. </dd>
    155. 

  155. </dl>
    156. 

  156. 

  157. <p>Any number of actions may be packed together in a single &lsquo;<samp>QTDP</samp>&rsquo;
    158. 

  158. packet, as long as the packet does not exceed the maximum packet
    159. 

  159. length (400 bytes, for many stubs).  There may be only one &lsquo;<samp>R</samp>&rsquo;
    160. 

  160. action per tracepoint, and it must precede any &lsquo;<samp>M</samp>&rsquo; or &lsquo;<samp>X</samp>&rsquo;
    161. 

  161. actions.  Any registers referred to by &lsquo;<samp>M</samp>&rsquo; and &lsquo;<samp>X</samp>&rsquo; actions
    162. 

  162. must be collected by a preceding &lsquo;<samp>R</samp>&rsquo; action.  (The
    163. 

  163. &ldquo;while-stepping&rdquo; actions are treated as if they were attached to a
    164. 

  164. separate tracepoint, as far as these restrictions are concerned.)
    165. 

  165. </p>
    166. 

  166. <p>Replies:
    167. 

  167. </p><dl compact="compact">
    168. 

  168. <dt>&lsquo;<samp>OK</samp>&rsquo;</dt>
    169. 

  169. <dd><p>The packet was understood and carried out.
    170. 

  170. </p></dd>
    171. 

  171. <dt>&lsquo;<samp>qRelocInsn</samp>&rsquo;</dt>
    172. 

  172. <dd><p>See <a href="#Tracepoint-Packets">Relocate instruction reply packet</a>.
    173. 

  173. </p></dd>
    174. 

  174. <dt>&lsquo;<samp><!-- /@w --></samp>&rsquo;</dt>
    175. 

  175. <dd><p>The packet was not recognized.
    176. 

  176. </p></dd>
    177. 

  177. </dl>
    178. 

  178. 

  179. </dd>
    180. 

  180. <dt>&lsquo;<samp>QTDPsrc:<var>n</var>:<var>addr</var>:<var>type</var>:<var>start</var>:<var>slen</var>:<var>bytes</var></samp>&rsquo;</dt>
    181. 

  181. <dd><a name="index-QTDPsrc-packet"></a>
    182. 

  182. <p>Specify a source string of tracepoint <var>n</var> at address <var>addr</var>.
    183. 

  183. This is useful to get accurate reproduction of the tracepoints
    184. 

  184. originally downloaded at the beginning of the trace run.  The <var>type</var>
    185. 

  185. is the name of the tracepoint part, such as &lsquo;<samp>cond</samp>&rsquo; for the
    186. 

  186. tracepoint&rsquo;s conditional expression (see below for a list of types), while
    187. 

  187. <var>bytes</var> is the string, encoded in hexadecimal.
    188. 

  188. </p>
    189. 

  189. <p><var>start</var> is the offset of the <var>bytes</var> within the overall source
    190. 

  190. string, while <var>slen</var> is the total length of the source string.
    191. 

  191. This is intended for handling source strings that are longer than will
    192. 

  192. fit in a single packet.
    193. 

  193. </p>
    194. 

  194. <p>The available string types are &lsquo;<samp>at</samp>&rsquo; for the location,
    195. 

  195. &lsquo;<samp>cond</samp>&rsquo; for the conditional, and &lsquo;<samp>cmd</samp>&rsquo; for an action command.
    196. 

  196. <small>GDB</small> sends a separate packet for each command in the action
    197. 

  197. list, in the same order in which the commands are stored in the list.
    198. 

  198. </p>
    199. 

  199. <p>The target does not need to do anything with source strings except
    200. 

  200. report them back as part of the replies to the &lsquo;<samp>qTfP</samp>&rsquo;/&lsquo;<samp>qTsP</samp>&rsquo;
    201. 

  201. query packets.
    202. 

  202. </p>
    203. 

  203. <p>Although this packet is optional, and <small>GDB</small> will only send it
    204. 

  204. if the target replies with &lsquo;<samp>TracepointSource</samp>&rsquo; See <a href="General-Query-Packets.html#General-Query-Packets">General Query Packets</a>, it makes both disconnected tracing and trace files
    205. 

  205. much easier to use.  Otherwise the user must be careful that the
    206. 

  206. tracepoints in effect while looking at trace frames are identical to
    207. 

  207. the ones in effect during the trace run; even a small discrepancy
    208. 

  208. could cause &lsquo;<samp>tdump</samp>&rsquo; not to work, or a particular trace frame not
    209. 

  209. be found.
    210. 

  210. </p>
    211. 

  211. </dd>
    212. 

  212. <dt>&lsquo;<samp>QTDV:<var>n</var>:<var>value</var>:<var>builtin</var>:<var>name</var></samp>&rsquo;</dt>
    213. 

  213. <dd><a name="index-define-trace-state-variable_002c-remote-request"></a>
    214. 

  214. <a name="index-QTDV-packet"></a>
    215. 

  215. <p>Create a new trace state variable, number <var>n</var>, with an initial
    216. 

  216. value of <var>value</var>, which is a 64-bit signed integer.  Both <var>n</var>
    217. 

  217. and <var>value</var> are encoded as hexadecimal values. <small>GDB</small> has
    218. 

  218. the option of not using this packet for initial values of zero; the
    219. 

  219. target should simply create the trace state variables as they are
    220. 

  220. mentioned in expressions.  The value <var>builtin</var> should be 1 (one)
    221. 

  221. if the trace state variable is builtin and 0 (zero) if it is not builtin.
    222. 

  222. <small>GDB</small> only sets <var>builtin</var> to 1 if a previous &lsquo;<samp>qTfV</samp>&rsquo; or
    223. 

  223. &lsquo;<samp>qTsV</samp>&rsquo; packet had it set.  The contents of <var>name</var> is the
    224. 

  224. hex-encoded name (without the leading &lsquo;<samp>$</samp>&rsquo;) of the trace state
    225. 

  225. variable.
    226. 

  226. </p>
    227. 

  227. </dd>
    228. 

  228. <dt>&lsquo;<samp>QTFrame:<var>n</var></samp>&rsquo;</dt>
    229. 

  229. <dd><a name="index-QTFrame-packet"></a>
    230. 

  230. <p>Select the <var>n</var>&rsquo;th tracepoint frame from the buffer, and use the
    231. 

  231. register and memory contents recorded there to answer subsequent
    232. 

  232. request packets from <small>GDB</small>.
    233. 

  233. </p>
    234. 

  234. <p>A successful reply from the stub indicates that the stub has found the
    235. 

  235. requested frame.  The response is a series of parts, concatenated
    236. 

  236. without separators, describing the frame we selected.  Each part has
    237. 

  237. one of the following forms:
    238. 

  238. </p>
    239. 

  239. <dl compact="compact">
    240. 

  240. <dt>&lsquo;<samp>F <var>f</var></samp>&rsquo;</dt>
    241. 

  241. <dd><p>The selected frame is number <var>n</var> in the trace frame buffer;
    242. 

  242. <var>f</var> is a hexadecimal number.  If <var>f</var> is &lsquo;<samp>-1</samp>&rsquo;, then there
    243. 

  243. was no frame matching the criteria in the request packet.
    244. 

  244. </p>
    245. 

  245. </dd>
    246. 

  246. <dt>&lsquo;<samp>T <var>t</var></samp>&rsquo;</dt>
    247. 

  247. <dd><p>The selected trace frame records a hit of tracepoint number <var>t</var>;
    248. 

  248. <var>t</var> is a hexadecimal number.
    249. 

  249. </p>
    250. 

  250. </dd>
    251. 

  251. </dl>
    252. 

  252. 

  253. </dd>
    254. 

  254. <dt>&lsquo;<samp>QTFrame:pc:<var>addr</var></samp>&rsquo;</dt>
    255. 

  255. <dd><p>Like &lsquo;<samp>QTFrame:<var>n</var></samp>&rsquo;, but select the first tracepoint frame after the
    256. 

  256. currently selected frame whose PC is <var>addr</var>;
    257. 

  257. <var>addr</var> is a hexadecimal number.
    258. 

  258. </p>
    259. 

  259. </dd>
    260. 

  260. <dt>&lsquo;<samp>QTFrame:tdp:<var>t</var></samp>&rsquo;</dt>
    261. 

  261. <dd><p>Like &lsquo;<samp>QTFrame:<var>n</var></samp>&rsquo;, but select the first tracepoint frame after the
    262. 

  262. currently selected frame that is a hit of tracepoint <var>t</var>; <var>t</var>
    263. 

  263. is a hexadecimal number.
    264. 

  264. </p>
    265. 

  265. </dd>
    266. 

  266. <dt>&lsquo;<samp>QTFrame:range:<var>start</var>:<var>end</var></samp>&rsquo;</dt>
    267. 

  267. <dd><p>Like &lsquo;<samp>QTFrame:<var>n</var></samp>&rsquo;, but select the first tracepoint frame after the
    268. 

  268. currently selected frame whose PC is between <var>start</var> (inclusive)
    269. 

  269. and <var>end</var> (inclusive); <var>start</var> and <var>end</var> are hexadecimal
    270. 

  270. numbers.
    271. 

  271. </p>
    272. 

  272. </dd>
    273. 

  273. <dt>&lsquo;<samp>QTFrame:outside:<var>start</var>:<var>end</var></samp>&rsquo;</dt>
    274. 

  274. <dd><p>Like &lsquo;<samp>QTFrame:range:<var>start</var>:<var>end</var></samp>&rsquo;, but select the first
    275. 

  275. frame <em>outside</em> the given range of addresses (exclusive).
    276. 

  276. </p>
    277. 

  277. </dd>
    278. 

  278. <dt>&lsquo;<samp>qTMinFTPILen</samp>&rsquo;</dt>
    279. 

  279. <dd><a name="index-qTMinFTPILen-packet"></a>
    280. 

  280. <p>This packet requests the minimum length of instruction at which a fast
    281. 

  281. tracepoint (see <a href="Set-Tracepoints.html#Set-Tracepoints">Set Tracepoints</a>) may be placed.  For instance, on
    282. 

  282. the 32-bit x86 architecture, it is possible to use a 4-byte jump, but
    283. 

  283. it depends on the target system being able to create trampolines in
    284. 

  284. the first 64K of memory, which might or might not be possible for that
    285. 

  285. system.  So the reply to this packet will be 4 if it is able to
    286. 

  286. arrange for that.
    287. 

  287. </p>
    288. 

  288. <p>Replies:
    289. 

  289. </p>
    290. 

  290. <dl compact="compact">
    291. 

  291. <dt>&lsquo;<samp>0</samp>&rsquo;</dt>
    292. 

  292. <dd><p>The minimum instruction length is currently unknown.
    293. 

  293. </p></dd>
    294. 

  294. <dt>&lsquo;<samp><var>length</var></samp>&rsquo;</dt>
    295. 

  295. <dd><p>The minimum instruction length is <var>length</var>, where <var>length</var>
    296. 

  296. is a hexadecimal number greater or equal to 1.  A reply
    297. 

  297. of 1 means that a fast tracepoint may be placed on any instruction
    298. 

  298. regardless of size.
    299. 

  299. </p></dd>
    300. 

  300. <dt>&lsquo;<samp>E</samp>&rsquo;</dt>
    301. 

  301. <dd><p>An error has occurred.
    302. 

  302. </p></dd>
    303. 

  303. <dt>&lsquo;<samp><!-- /@w --></samp>&rsquo;</dt>
    304. 

  304. <dd><p>An empty reply indicates that the request is not supported by the stub.
    305. 

  305. </p></dd>
    306. 

  306. </dl>
    307. 

  307. 

  308. </dd>
    309. 

  309. <dt>&lsquo;<samp>QTStart</samp>&rsquo;</dt>
    310. 

  310. <dd><a name="index-QTStart-packet"></a>
    311. 

  311. <p>Begin the tracepoint experiment.  Begin collecting data from
    312. 

  312. tracepoint hits in the trace frame buffer.  This packet supports the
    313. 

  313. &lsquo;<samp>qRelocInsn</samp>&rsquo; reply (see <a href="#Tracepoint-Packets">Relocate
    314. 

  314. instruction reply packet</a>).
    315. 

  315. </p>
    316. 

  316. </dd>
    317. 

  317. <dt>&lsquo;<samp>QTStop</samp>&rsquo;</dt>
    318. 

  318. <dd><a name="index-QTStop-packet"></a>
    319. 

  319. <p>End the tracepoint experiment.  Stop collecting trace frames.
    320. 

  320. </p>
    321. 

  321. </dd>
    322. 

  322. <dt>&lsquo;<samp>QTEnable:<var>n</var>:<var>addr</var></samp>&rsquo;</dt>
    323. 

  323. <dd><a name="QTEnable"></a><a name="index-QTEnable-packet"></a>
    324. 

  324. <p>Enable tracepoint <var>n</var> at address <var>addr</var> in a started tracepoint
    325. 

  325. experiment.  If the tracepoint was previously disabled, then collection
    326. 

  326. of data from it will resume.
    327. 

  327. </p>
    328. 

  328. </dd>
    329. 

  329. <dt>&lsquo;<samp>QTDisable:<var>n</var>:<var>addr</var></samp>&rsquo;</dt>
    330. 

  330. <dd><a name="QTDisable"></a><a name="index-QTDisable-packet"></a>
    331. 

  331. <p>Disable tracepoint <var>n</var> at address <var>addr</var> in a started tracepoint
    332. 

  332. experiment.  No more data will be collected from the tracepoint unless
    333. 

  333. &lsquo;<samp>QTEnable:<var>n</var>:<var>addr</var></samp>&rsquo; is subsequently issued.
    334. 

  334. </p>
    335. 

  335. </dd>
    336. 

  336. <dt>&lsquo;<samp>QTinit</samp>&rsquo;</dt>
    337. 

  337. <dd><a name="index-QTinit-packet"></a>
    338. 

  338. <p>Clear the table of tracepoints, and empty the trace frame buffer.
    339. 

  339. </p>
    340. 

  340. </dd>
    341. 

  341. <dt>&lsquo;<samp>QTro:<var>start1</var>,<var>end1</var>:<var>start2</var>,<var>end2</var>:&hellip;</samp>&rsquo;</dt>
    342. 

  342. <dd><a name="index-QTro-packet"></a>
    343. 

  343. <p>Establish the given ranges of memory as &ldquo;transparent&rdquo;.  The stub
    344. 

  344. will answer requests for these ranges from memory&rsquo;s current contents,
    345. 

  345. if they were not collected as part of the tracepoint hit.
    346. 

  346. </p>
    347. 

  347. <p><small>GDB</small> uses this to mark read-only regions of memory, like those
    348. 

  348. containing program code.  Since these areas never change, they should
    349. 

  349. still have the same contents they did when the tracepoint was hit, so
    350. 

  350. there&rsquo;s no reason for the stub to refuse to provide their contents.
    351. 

  351. </p>
    352. 

  352. </dd>
    353. 

  353. <dt>&lsquo;<samp>QTDisconnected:<var>value</var></samp>&rsquo;</dt>
    354. 

  354. <dd><a name="index-QTDisconnected-packet"></a>
    355. 

  355. <p>Set the choice to what to do with the tracing run when <small>GDB</small>
    356. 

  356. disconnects from the target.  A <var>value</var> of 1 directs the target to
    357. 

  357. continue the tracing run, while 0 tells the target to stop tracing if
    358. 

  358. <small>GDB</small> is no longer in the picture.
    359. 

  359. </p>
    360. 

  360. </dd>
    361. 

  361. <dt>&lsquo;<samp>qTStatus</samp>&rsquo;</dt>
    362. 

  362. <dd><a name="index-qTStatus-packet"></a>
    363. 

  363. <p>Ask the stub if there is a trace experiment running right now.
    364. 

  364. </p>
    365. 

  365. <p>The reply has the form:
    366. 

  366. </p>
    367. 

  367. <dl compact="compact">
    368. 

  368. <dt>&lsquo;<samp>T<var>running</var><span class="roman">[</span>;<var>field</var><span class="roman">]</span>&hellip;</samp>&rsquo;</dt>
    369. 

  369. <dd><p><var>running</var> is a single digit <code>1</code> if the trace is presently
    370. 

  370. running, or <code>0</code> if not.  It is followed by semicolon-separated
    371. 

  371. optional fields that an agent may use to report additional status.
    372. 

  372. </p>
    373. 

  373. </dd>
    374. 

  374. </dl>
    375. 

  375. 

  376. <p>If the trace is not running, the agent may report any of several
    377. 

  377. explanations as one of the optional fields:
    378. 

  378. </p>
    379. 

  379. <dl compact="compact">
    380. 

  380. <dt>&lsquo;<samp>tnotrun:0</samp>&rsquo;</dt>
    381. 

  381. <dd><p>No trace has been run yet.
    382. 

  382. </p>
    383. 

  383. </dd>
    384. 

  384. <dt>&lsquo;<samp>tstop[:<var>text</var>]:0</samp>&rsquo;</dt>
    385. 

  385. <dd><p>The trace was stopped by a user-originated stop command.  The optional
    386. 

  386. <var>text</var> field is a user-supplied string supplied as part of the
    387. 

  387. stop command (for instance, an explanation of why the trace was
    388. 

  388. stopped manually).  It is hex-encoded.
    389. 

  389. </p>
    390. 

  390. </dd>
    391. 

  391. <dt>&lsquo;<samp>tfull:0</samp>&rsquo;</dt>
    392. 

  392. <dd><p>The trace stopped because the trace buffer filled up.
    393. 

  393. </p>
    394. 

  394. </dd>
    395. 

  395. <dt>&lsquo;<samp>tdisconnected:0</samp>&rsquo;</dt>
    396. 

  396. <dd><p>The trace stopped because <small>GDB</small> disconnected from the target.
    397. 

  397. </p>
    398. 

  398. </dd>
    399. 

  399. <dt>&lsquo;<samp>tpasscount:<var>tpnum</var></samp>&rsquo;</dt>
    400. 

  400. <dd><p>The trace stopped because tracepoint <var>tpnum</var> exceeded its pass count.
    401. 

  401. </p>
    402. 

  402. </dd>
    403. 

  403. <dt>&lsquo;<samp>terror:<var>text</var>:<var>tpnum</var></samp>&rsquo;</dt>
    404. 

  404. <dd><p>The trace stopped because tracepoint <var>tpnum</var> had an error.  The
    405. 

  405. string <var>text</var> is available to describe the nature of the error
    406. 

  406. (for instance, a divide by zero in the condition expression); it
    407. 

  407. is hex encoded.
    408. 

  408. </p>
    409. 

  409. </dd>
    410. 

  410. <dt>&lsquo;<samp>tunknown:0</samp>&rsquo;</dt>
    411. 

  411. <dd><p>The trace stopped for some other reason.
    412. 

  412. </p>
    413. 

  413. </dd>
    414. 

  414. </dl>
    415. 

  415. 

  416. <p>Additional optional fields supply statistical and other information.
    417. 

  417. Although not required, they are extremely useful for users monitoring
    418. 

  418. the progress of a trace run.  If a trace has stopped, and these
    419. 

  419. numbers are reported, they must reflect the state of the just-stopped
    420. 

  420. trace.
    421. 

  421. </p>
    422. 

  422. <dl compact="compact">
    423. 

  423. <dt>&lsquo;<samp>tframes:<var>n</var></samp>&rsquo;</dt>
    424. 

  424. <dd><p>The number of trace frames in the buffer.
    425. 

  425. </p>
    426. 

  426. </dd>
    427. 

  427. <dt>&lsquo;<samp>tcreated:<var>n</var></samp>&rsquo;</dt>
    428. 

  428. <dd><p>The total number of trace frames created during the run. This may
    429. 

  429. be larger than the trace frame count, if the buffer is circular.
    430. 

  430. </p>
    431. 

  431. </dd>
    432. 

  432. <dt>&lsquo;<samp>tsize:<var>n</var></samp>&rsquo;</dt>
    433. 

  433. <dd><p>The total size of the trace buffer, in bytes.
    434. 

  434. </p>
    435. 

  435. </dd>
    436. 

  436. <dt>&lsquo;<samp>tfree:<var>n</var></samp>&rsquo;</dt>
    437. 

  437. <dd><p>The number of bytes still unused in the buffer.
    438. 

  438. </p>
    439. 

  439. </dd>
    440. 

  440. <dt>&lsquo;<samp>circular:<var>n</var></samp>&rsquo;</dt>
    441. 

  441. <dd><p>The value of the circular trace buffer flag.  <code>1</code> means that the
    442. 

  442. trace buffer is circular and old trace frames will be discarded if
    443. 

  443. necessary to make room, <code>0</code> means that the trace buffer is linear
    444. 

  444. and may fill up.
    445. 

  445. </p>
    446. 

  446. </dd>
    447. 

  447. <dt>&lsquo;<samp>disconn:<var>n</var></samp>&rsquo;</dt>
    448. 

  448. <dd><p>The value of the disconnected tracing flag.  <code>1</code> means that
    449. 

  449. tracing will continue after <small>GDB</small> disconnects, <code>0</code> means
    450. 

  450. that the trace run will stop.
    451. 

  451. </p>
    452. 

  452. </dd>
    453. 

  453. </dl>
    454. 

  454. 

  455. </dd>
    456. 

  456. <dt>&lsquo;<samp>qTP:<var>tp</var>:<var>addr</var></samp>&rsquo;</dt>
    457. 

  457. <dd><a name="index-tracepoint-status_002c-remote-request"></a>
    458. 

  458. <a name="index-qTP-packet"></a>
    459. 

  459. <p>Ask the stub for the current state of tracepoint number <var>tp</var> at
    460. 

  460. address <var>addr</var>.
    461. 

  461. </p>
    462. 

  462. <p>Replies:
    463. 

  463. </p><dl compact="compact">
    464. 

  464. <dt>&lsquo;<samp>V<var>hits</var>:<var>usage</var></samp>&rsquo;</dt>
    465. 

  465. <dd><p>The tracepoint has been hit <var>hits</var> times so far during the trace
    466. 

  466. run, and accounts for <var>usage</var> in the trace buffer.  Note that
    467. 

  467. <code>while-stepping</code> steps are not counted as separate hits, but the
    468. 

  468. steps&rsquo; space consumption is added into the usage number.
    469. 

  469. </p>
    470. 

  470. </dd>
    471. 

  471. </dl>
    472. 

  472. 

  473. </dd>
    474. 

  474. <dt>&lsquo;<samp>qTV:<var>var</var></samp>&rsquo;</dt>
    475. 

  475. <dd><a name="index-trace-state-variable-value_002c-remote-request"></a>
    476. 

  476. <a name="index-qTV-packet"></a>
    477. 

  477. <p>Ask the stub for the value of the trace state variable number <var>var</var>.
    478. 

  478. </p>
    479. 

  479. <p>Replies:
    480. 

  480. </p><dl compact="compact">
    481. 

  481. <dt>&lsquo;<samp>V<var>value</var></samp>&rsquo;</dt>
    482. 

  482. <dd><p>The value of the variable is <var>value</var>.  This will be the current
    483. 

  483. value of the variable if the user is examining a running target, or a
    484. 

  484. saved value if the variable was collected in the trace frame that the
    485. 

  485. user is looking at.  Note that multiple requests may result in
    486. 

  486. different reply values, such as when requesting values while the
    487. 

  487. program is running.
    488. 

  488. </p>
    489. 

  489. </dd>
    490. 

  490. <dt>&lsquo;<samp>U</samp>&rsquo;</dt>
    491. 

  491. <dd><p>The value of the variable is unknown.  This would occur, for example,
    492. 

  492. if the user is examining a trace frame in which the requested variable
    493. 

  493. was not collected.
    494. 

  494. </p></dd>
    495. 

  495. </dl>
    496. 

  496. 

  497. </dd>
    498. 

  498. <dt>&lsquo;<samp>qTfP</samp>&rsquo;</dt>
    499. 

  499. <dd><a name="index-qTfP-packet"></a>
    500. 

  500. </dd>
    501. 

  501. <dt>&lsquo;<samp>qTsP</samp>&rsquo;</dt>
    502. 

  502. <dd><a name="index-qTsP-packet"></a>
    503. 

  503. <p>These packets request data about tracepoints that are being used by
    504. 

  504. the target.  <small>GDB</small> sends <code>qTfP</code> to get the first piece
    505. 

  505. of data, and multiple <code>qTsP</code> to get additional pieces.  Replies
    506. 

  506. to these packets generally take the form of the <code>QTDP</code> packets
    507. 

  507. that define tracepoints. (FIXME add detailed syntax)
    508. 

  508. </p>
    509. 

  509. </dd>
    510. 

  510. <dt>&lsquo;<samp>qTfV</samp>&rsquo;</dt>
    511. 

  511. <dd><a name="index-qTfV-packet"></a>
    512. 

  512. </dd>
    513. 

  513. <dt>&lsquo;<samp>qTsV</samp>&rsquo;</dt>
    514. 

  514. <dd><a name="index-qTsV-packet"></a>
    515. 

  515. <p>These packets request data about trace state variables that are on the
    516. 

  516. target.  <small>GDB</small> sends <code>qTfV</code> to get the first vari of data,
    517. 

  517. and multiple <code>qTsV</code> to get additional variables.  Replies to
    518. 

  518. these packets follow the syntax of the <code>QTDV</code> packets that define
    519. 

  519. trace state variables.
    520. 

  520. </p>
    521. 

  521. </dd>
    522. 

  522. <dt>&lsquo;<samp>qTfSTM</samp>&rsquo;</dt>
    523. 

  523. <dt>&lsquo;<samp>qTsSTM</samp>&rsquo;</dt>
    524. 

  524. <dd><a name="qTfSTM"></a><a name="qTsSTM"></a><a name="index-qTfSTM-packet"></a>
    525. 

  525. <a name="index-qTsSTM-packet"></a>
    526. 

  526. <p>These packets request data about static tracepoint markers that exist
    527. 

  527. in the target program.  <small>GDB</small> sends <code>qTfSTM</code> to get the
    528. 

  528. first piece of data, and multiple <code>qTsSTM</code> to get additional
    529. 

  529. pieces.  Replies to these packets take the following form:
    530. 

  530. </p>
    531. 

  531. <p>Reply:
    532. 

  532. </p><dl compact="compact">
    533. 

  533. <dt>&lsquo;<samp>m <var>address</var>:<var>id</var>:<var>extra</var></samp>&rsquo;</dt>
    534. 

  534. <dd><p>A single marker
    535. 

  535. </p></dd>
    536. 

  536. <dt>&lsquo;<samp>m <var>address</var>:<var>id</var>:<var>extra</var>,<var>address</var>:<var>id</var>:<var>extra</var>&hellip;</samp>&rsquo;</dt>
    537. 

  537. <dd><p>a comma-separated list of markers
    538. 

  538. </p></dd>
    539. 

  539. <dt>&lsquo;<samp>l</samp>&rsquo;</dt>
    540. 

  540. <dd><p>(lower case letter &lsquo;<samp>L</samp>&rsquo;) denotes end of list.
    541. 

  541. </p></dd>
    542. 

  542. <dt>&lsquo;<samp>E <var>nn</var></samp>&rsquo;</dt>
    543. 

  543. <dd><p>An error occurred.  The error number <var>nn</var> is given as hex digits.
    544. 

  544. </p></dd>
    545. 

  545. <dt>&lsquo;<samp><!-- /@w --></samp>&rsquo;</dt>
    546. 

  546. <dd><p>An empty reply indicates that the request is not supported by the
    547. 

  547. stub.
    548. 

  548. </p></dd>
    549. 

  549. </dl>
    550. 

  550. 

  551. <p>The <var>address</var> is encoded in hex;
    552. 

  552. <var>id</var> and <var>extra</var> are strings encoded in hex.
    553. 

  553. </p>
    554. 

  554. <p>In response to each query, the target will reply with a list of one or
    555. 

  555. more markers, separated by commas.  <small>GDB</small> will respond to each
    556. 

  556. reply with a request for more markers (using the &lsquo;<samp>qs</samp>&rsquo; form of the
    557. 

  557. query), until the target responds with &lsquo;<samp>l</samp>&rsquo; (lower-case ell, for
    558. 

  558. <em>last</em>).
    559. 

  559. </p>
    560. 

  560. </dd>
    561. 

  561. <dt>&lsquo;<samp>qTSTMat:<var>address</var></samp>&rsquo;</dt>
    562. 

  562. <dd><a name="qTSTMat"></a><a name="index-qTSTMat-packet"></a>
    563. 

  563. <p>This packets requests data about static tracepoint markers in the
    564. 

  564. target program at <var>address</var>.  Replies to this packet follow the
    565. 

  565. syntax of the &lsquo;<samp>qTfSTM</samp>&rsquo; and <code>qTsSTM</code> packets that list static
    566. 

  566. tracepoint markers.
    567. 

  567. </p>
    568. 

  568. </dd>
    569. 

  569. <dt>&lsquo;<samp>QTSave:<var>filename</var></samp>&rsquo;</dt>
    570. 

  570. <dd><a name="index-QTSave-packet"></a>
    571. 

  571. <p>This packet directs the target to save trace data to the file name
    572. 

  572. <var>filename</var> in the target&rsquo;s filesystem.  The <var>filename</var> is encoded
    573. 

  573. as a hex string; the interpretation of the file name (relative vs
    574. 

  574. absolute, wild cards, etc) is up to the target.
    575. 

  575. </p>
    576. 

  576. </dd>
    577. 

  577. <dt>&lsquo;<samp>qTBuffer:<var>offset</var>,<var>len</var></samp>&rsquo;</dt>
    578. 

  578. <dd><a name="index-qTBuffer-packet"></a>
    579. 

  579. <p>Return up to <var>len</var> bytes of the current contents of trace buffer,
    580. 

  580. starting at <var>offset</var>.  The trace buffer is treated as if it were
    581. 

  581. a contiguous collection of traceframes, as per the trace file format.
    582. 

  582. The reply consists as many hex-encoded bytes as the target can deliver
    583. 

  583. in a packet; it is not an error to return fewer than were asked for.
    584. 

  584. A reply consisting of just <code>l</code> indicates that no bytes are
    585. 

  585. available.
    586. 

  586. </p>
    587. 

  587. </dd>
    588. 

  588. <dt>&lsquo;<samp>QTBuffer:circular:<var>value</var></samp>&rsquo;</dt>
    589. 

  589. <dd><p>This packet directs the target to use a circular trace buffer if
    590. 

  590. <var>value</var> is 1, or a linear buffer if the value is 0.
    591. 

  591. </p>
    592. 

  592. </dd>
    593. 

  593. <dt>&lsquo;<samp>QTBuffer:size:<var>size</var></samp>&rsquo;</dt>
    594. 

  594. <dd><a name="QTBuffer_002dsize"></a><a name="index-QTBuffer-size-packet"></a>
    595. 

  595. <p>This packet directs the target to make the trace buffer be of size
    596. 

  596. <var>size</var> if possible.  A value of <code>-1</code> tells the target to
    597. 

  597. use whatever size it prefers.
    598. 

  598. </p>
    599. 

  599. </dd>
    600. 

  600. <dt>&lsquo;<samp>QTNotes:<span class="roman">[</span><var>type</var>:<var>text</var><span class="roman">]</span><span class="roman">[</span>;<var>type</var>:<var>text</var><span class="roman">]</span>&hellip;</samp>&rsquo;</dt>
    601. 

  601. <dd><a name="index-QTNotes-packet"></a>
    602. 

  602. <p>This packet adds optional textual notes to the trace run.  Allowable
    603. 

  603. types include <code>user</code>, <code>notes</code>, and <code>tstop</code>, the
    604. 

  604. <var>text</var> fields are arbitrary strings, hex-encoded.
    605. 

  605. </p>
    606. 

  606. </dd>
    607. 

  607. </dl>
    608. 

  608. 

  609. <a name="Relocate-instruction-reply-packet"></a>
    610. 

  610. <h4 class="subsection">E.6.1 Relocate instruction reply packet</h4>
    611. 

  611. <p>When installing fast tracepoints in memory, the target may need to
    612. 

  612. relocate the instruction currently at the tracepoint address to a
    613. 

  613. different address in memory.  For most instructions, a simple copy is
    614. 

  614. enough, but, for example, call instructions that implicitly push the
    615. 

  615. return address on the stack, and relative branches or other
    616. 

  616. PC-relative instructions require offset adjustment, so that the effect
    617. 

  617. of executing the instruction at a different address is the same as if
    618. 

  618. it had executed in the original location.
    619. 

  619. </p>
    620. 

  620. <p>In response to several of the tracepoint packets, the target may also
    621. 

  621. respond with a number of intermediate &lsquo;<samp>qRelocInsn</samp>&rsquo; request
    622. 

  622. packets before the final result packet, to have <small>GDB</small> handle
    623. 

  623. this relocation operation.  If a packet supports this mechanism, its
    624. 

  624. documentation will explicitly say so.  See for example the above
    625. 

  625. descriptions for the &lsquo;<samp>QTStart</samp>&rsquo; and &lsquo;<samp>QTDP</samp>&rsquo; packets.  The
    626. 

  626. format of the request is:
    627. 

  627. </p>
    628. 

  628. <dl compact="compact">
    629. 

  629. <dt>&lsquo;<samp>qRelocInsn:<var>from</var>;<var>to</var></samp>&rsquo;</dt>
    630. 

  630. <dd>
    631. 

  631. <p>This requests <small>GDB</small> to copy instruction at address <var>from</var>
    632. 

  632. to address <var>to</var>, possibly adjusted so that executing the
    633. 

  633. instruction at <var>to</var> has the same effect as executing it at
    634. 

  634. <var>from</var>.  <small>GDB</small> writes the adjusted instruction to target
    635. 

  635. memory starting at <var>to</var>.
    636. 

  636. </p></dd>
    637. 

  637. </dl>
    638. 

  638. 

  639. <p>Replies:
    640. 

  640. </p><dl compact="compact">
    641. 

  641. <dt>&lsquo;<samp>qRelocInsn:<var>adjusted_size</var></samp>&rsquo;</dt>
    642. 

  642. <dd><p>Informs the stub the relocation is complete.  The <var>adjusted_size</var> is
    643. 

  643. the length in bytes of resulting relocated instruction sequence.
    644. 

  644. </p></dd>
    645. 

  645. <dt>&lsquo;<samp>E <var>NN</var></samp>&rsquo;</dt>
    646. 

  646. <dd><p>A badly formed request was detected, or an error was encountered while
    647. 

  647. relocating the instruction.
    648. 

  648. </p></dd>
    649. 

  649. </dl>
    650. 

  650. 

  651. <hr>
    652. 

  652. <div class="header">
    653. 

  653. <p>
    654. 

  654. Next: <a href="Host-I_002fO-Packets.html#Host-I_002fO-Packets" accesskey="n" rel="next">Host I/O Packets</a>, Previous: <a href="Architecture_002dSpecific-Protocol-Details.html#Architecture_002dSpecific-Protocol-Details" accesskey="p" rel="previous">Architecture-Specific Protocol Details</a>, Up: <a href="Remote-Protocol.html#Remote-Protocol" accesskey="u" rel="up">Remote Protocol</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
    655. 

  655. </div>
    656. 

  656. 

  657. 

  658. 

  659. </body>
    660. 

  660. </html>
    661.