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diff --git a/share/doc/gdb/Notification-Packets.html b/share/doc/gdb/Notification-Packets.html new file mode 100644 index 0000000..fb25449 --- /dev/null +++ b/share/doc/gdb/Notification-Packets.html @@ -0,0 +1,199 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Free Software" and "Free Software Needs +Free Documentation", with the Front-Cover Texts being "A GNU Manual," +and with the Back-Cover Texts as in (a) below. + +(a) The FSF's Back-Cover Text is: "You are free to copy and modify +this GNU Manual. Buying copies from GNU Press supports the FSF in +developing GNU and promoting software freedom." --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Debugging with GDB: Notification Packets</title> + +<meta name="description" content="Debugging with GDB: Notification Packets"> +<meta name="keywords" content="Debugging with GDB: Notification Packets"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Remote-Protocol.html#Remote-Protocol" rel="up" title="Remote Protocol"> +<link href="Remote-Non_002dStop.html#Remote-Non_002dStop" rel="next" title="Remote Non-Stop"> +<link href="Interrupts.html#Interrupts" rel="previous" title="Interrupts"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Notification-Packets"></a> +<div class="header"> +<p> +Next: <a href="Remote-Non_002dStop.html#Remote-Non_002dStop" accesskey="n" rel="next">Remote Non-Stop</a>, Previous: <a href="Interrupts.html#Interrupts" accesskey="p" rel="previous">Interrupts</a>, Up: <a href="Remote-Protocol.html#Remote-Protocol" accesskey="u" rel="up">Remote Protocol</a> [<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> +</div> +<hr> +<a name="Notification-Packets-1"></a> +<h3 class="section">E.9 Notification Packets</h3> +<a name="index-notification-packets"></a> +<a name="index-packets_002c-notification"></a> + +<p>The <small>GDB</small> remote serial protocol includes <em>notifications</em>, +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> +<p>A notification packet has the form ‘<samp>% <var>data</var> # +<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 <small>GDB</small> packets. A notification’s <var>data</var> +never contains ‘<samp>$</samp>’, ‘<samp>%</samp>’ or ‘<samp>#</samp>’ characters. Upon +receiving a notification, the recipient sends no ‘<samp>+</samp>’ or ‘<samp>-</samp>’ +to acknowledge the notification’s receipt or to report its corruption. +</p> +<p>Every notification’s <var>data</var> begins with a name, which contains no +colon characters, followed by a colon character. +</p> +<p>Recipients should silently ignore corrupted notifications and +notifications they do not understand. Recipients should restart +timeout periods on receipt of a well-formed notification, whether or +not they understand it. +</p> +<p>Senders should only send the notifications described here when this +protocol description specifies that they are permitted. In the +future, we may extend the protocol to permit existing notifications in +new contexts; this rule helps older senders avoid confusing newer +recipients. +</p> +<p>(Older versions of <small>GDB</small> ignore bytes received until they see +the ‘<samp>$</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 <small>GDB</small> to send at the moment, but we +assume that most older stubs would ignore them, as well.) +</p> +<p>Each notification is comprised of three parts: +</p><dl compact="compact"> +<dt>‘<samp><var>name</var>:<var>event</var></samp>’</dt> +<dd><p>The notification packet is sent by the side that initiates the +exchange (currently, only the stub does that), with <var>event</var> +carrying the specific information about the notification, and +<var>name</var> specifying the name of the notification. +</p></dd> +<dt>‘<samp><var>ack</var></samp>’</dt> +<dd><p>The acknowledge sent by the other side, usually <small>GDB</small>, to +acknowledge the exchange and request the event. +</p></dd> +</dl> + +<p>The purpose of an asynchronous notification mechanism is to report to +<small>GDB</small> that something interesting happened in the remote stub. +</p> +<p>The remote stub may send notification <var>name</var>:<var>event</var> +at any time, but <small>GDB</small> acknowledges the notification when +appropriate. The notification event is pending before <small>GDB</small> +acknowledges. Only one notification at a time may be pending; if +additional events occur before <small>GDB</small> has acknowledged the +previous notification, they must be queued by the stub for later +synchronous transmission in response to <var>ack</var> packets from +<small>GDB</small>. Because the notification mechanism is unreliable, +the stub is permitted to resend a notification if it believes +<small>GDB</small> may not have received it. +</p> +<p>Specifically, notifications may appear when <small>GDB</small> is not +otherwise reading input from the stub, or when <small>GDB</small> is +expecting to read a normal synchronous response or a +‘<samp>+</samp>’/‘<samp>-</samp>’ acknowledgment to a packet it has sent. +Notification packets are distinct from any other communication from +the stub so there is no ambiguity. +</p> +<p>After receiving a notification, <small>GDB</small> shall acknowledge it by +sending a <var>ack</var> packet as a regular, synchronous request to the +stub. Such acknowledgment is not required to happen immediately, as +<small>GDB</small> is permitted to send other, unrelated packets to the +stub first, which the stub should process normally. +</p> +<p>Upon receiving a <var>ack</var> packet, if the stub has other queued +events to report to <small>GDB</small>, it shall respond by sending a +normal <var>event</var>. <small>GDB</small> shall then send another <var>ack</var> +packet to solicit further responses; again, it is permitted to send +other, unrelated packets as well which the stub should process +normally. +</p> +<p>If the stub receives a <var>ack</var> packet and there are no additional +<var>event</var> to report, the stub shall return an ‘<samp>OK</samp>’ response. +At this point, <small>GDB</small> has finished processing a notification +and the stub has completed sending any queued events. <small>GDB</small> +won’t accept any new notifications until the final ‘<samp>OK</samp>’ is +received . If further notification events occur, the stub shall send +a new notification, <small>GDB</small> shall accept the notification, and +the process shall be repeated. +</p> +<p>The process of asynchronous notification can be illustrated by the +following example: +</p><div class="smallexample"> +<pre class="smallexample"><- <code>%Stop:T0505:98e7ffbf;04:4ce6ffbf;08:b1b6e54c;thread:p7526.7526;core:0;</code> +<code>...</code> +-> <code>vStopped</code> +<- <code>T0505:68f37db7;04:40f37db7;08:63850408;thread:p7526.7528;core:0;</code> +-> <code>vStopped</code> +<- <code>T0505:68e3fdb6;04:40e3fdb6;08:63850408;thread:p7526.7529;core:0;</code> +-> <code>vStopped</code> +<- <code>OK</code> +</pre></div> + +<p>The following notifications are defined: +</p><table> +<tr><td width="12%">Notification</td><td width="12%">Ack</td><td width="38%">Event</td><td width="38%">Description</td></tr> +<tr><td width="12%">Stop</td><td width="12%">vStopped</td><td width="38%"><var>reply</var>. 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 +<small>GDB</small>.</td><td width="38%">Report an asynchronous stop event in non-stop mode.</td></tr> +</table> + +<hr> +<div class="header"> +<p> +Next: <a href="Remote-Non_002dStop.html#Remote-Non_002dStop" accesskey="n" rel="next">Remote Non-Stop</a>, Previous: <a href="Interrupts.html#Interrupts" accesskey="p" rel="previous">Interrupts</a>, Up: <a href="Remote-Protocol.html#Remote-Protocol" accesskey="u" rel="up">Remote Protocol</a> [<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> +</div> + + + +</body> +</html> |