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| <h3 class="section">D.10 Notification Packets</h3> |
| |
| <p><a name="index-notification-packets-2490"></a><a name="index-packets_002c-notification-2491"></a> |
| The <span class="sc">gdb</span> remote serial protocol includes <dfn>notifications</dfn>, |
| packets that require no acknowledgment. Both the GDB and the stub |
| may send notifications (although the only notifications defined at |
| present are sent by the stub). Notifications carry information |
| without incurring the round-trip latency of an acknowledgment, and so |
| are useful for low-impact communications where occasional packet loss |
| is not a problem. |
| |
| <p>A notification packet has the form ‘<samp><span class="samp">% </span><var>data</var><span class="samp"> # |
| </span><var>checksum</var></samp>’, where <var>data</var> is the content of the notification, |
| and <var>checksum</var> is a checksum of <var>data</var>, computed and formatted |
| as for ordinary <span class="sc">gdb</span> packets. A notification's <var>data</var> |
| never contains ‘<samp><span class="samp">$</span></samp>’, ‘<samp><span class="samp">%</span></samp>’ or ‘<samp><span class="samp">#</span></samp>’ characters. Upon |
| receiving a notification, the recipient sends no ‘<samp><span class="samp">+</span></samp>’ or ‘<samp><span class="samp">-</span></samp>’ |
| to acknowledge the notification's receipt or to report its corruption. |
| |
| <p>Every notification's <var>data</var> begins with a name, which contains no |
| colon characters, followed by a colon character. |
| |
| <p>Recipients should silently ignore corrupted notifications and |
| notifications they do not understand. Recipients should restart |
| timeout periods on receipt of a well-formed notification, whether or |
| not they understand it. |
| |
| <p>Senders should only send the notifications described here when this |
| protocol description specifies that they are permitted. In the |
| future, we may extend the protocol to permit existing notifications in |
| new contexts; this rule helps older senders avoid confusing newer |
| recipients. |
| |
| <p>(Older versions of <span class="sc">gdb</span> ignore bytes received until they see |
| the ‘<samp><span class="samp">$</span></samp>’ byte that begins an ordinary packet, so new stubs may |
| transmit notifications without fear of confusing older clients. There |
| are no notifications defined for <span class="sc">gdb</span> to send at the moment, but we |
| assume that most older stubs would ignore them, as well.) |
| |
| <p>The following notification packets from the stub to <span class="sc">gdb</span> are |
| defined: |
| |
| <dl> |
| <dt>‘<samp><span class="samp">Stop: </span><var>reply</var></samp>’<dd>Report an asynchronous stop event in non-stop mode. |
| The <var>reply</var> has the form of a stop reply, as |
| described in <a href="Stop-Reply-Packets.html#Stop-Reply-Packets">Stop Reply Packets</a>. Refer to <a href="Remote-Non_002dStop.html#Remote-Non_002dStop">Remote Non-Stop</a>, |
| for information on how these notifications are acknowledged by |
| <span class="sc">gdb</span>. |
| </dl> |
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