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<a name="Varying-Target-Capabilities"></a>
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Next: <a href="Rationale.html#Rationale" accesskey="n" rel="next">Rationale</a>, Previous: <a href="Using-Agent-Expressions.html#Using-Agent-Expressions" accesskey="p" rel="previous">Using Agent Expressions</a>, Up: <a href="Agent-Expressions.html#Agent-Expressions" accesskey="u" rel="up">Agent Expressions</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>
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<a name="Varying-Target-Capabilities-1"></a>
<h3 class="section">F.4 Varying Target Capabilities</h3>

<p>Some targets don&rsquo;t support floating-point, and some would rather not
have to deal with <code>long long</code> operations.  Also, different targets
will have different stack sizes, and different bytecode buffer lengths.
</p>
<p>Thus, GDB needs a way to ask the target about itself.  We haven&rsquo;t worked
out the details yet, but in general, GDB should be able to send the
target a packet asking it to describe itself.  The reply should be a
packet whose length is explicit, so we can add new information to the
packet in future revisions of the agent, without confusing old versions
of GDB, and it should contain a version number.  It should contain at
least the following information:
</p>
<ul>
<li> whether floating point is supported

</li><li> whether <code>long long</code> is supported

</li><li> maximum acceptable size of bytecode stack

</li><li> maximum acceptable length of bytecode expressions

</li><li> which registers are actually available for collection

</li><li> whether the target supports disabled tracepoints

</li></ul>


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