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<a name="BPF_002dRegs"></a>
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Next: <a href="BPF_002dPseudo_002dMaps.html#BPF_002dPseudo_002dMaps" accesskey="n" rel="next">BPF-Pseudo-Maps</a>, Previous: <a href="BPF_002dChars.html#BPF_002dChars" accesskey="p" rel="prev">BPF-Chars</a>, Up: <a href="BPF-Syntax.html#BPF-Syntax" accesskey="u" rel="up">BPF Syntax</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Register-Names-5"></a>
<h4 class="subsubsection">9.7.2.2 Register Names</h4>

<a name="index-BPF-register-names"></a>
<a name="index-register-names_002c-BPF"></a>
<p>The eBPF processor provides ten general-purpose 64-bit registers,
which are read-write, and a read-only frame pointer register:
</p>
<dl compact="compact">
<dt>&lsquo;<samp>%r0 .. %r9</samp>&rsquo;</dt>
<dd><p>General-purpose registers.
</p></dd>
<dt>&lsquo;<samp>%r10</samp>&rsquo;</dt>
<dd><p>Frame pointer register.
</p></dd>
</dl>

<p>Some registers have additional names, to reflect their role in the
eBPF ABI:
</p>
<dl compact="compact">
<dt>&lsquo;<samp>%a</samp>&rsquo;</dt>
<dd><p>This is &lsquo;<samp>%r0</samp>&rsquo;.
</p></dd>
<dt>&lsquo;<samp>%ctx</samp>&rsquo;</dt>
<dd><p>This is &lsquo;<samp>%r6</samp>&rsquo;.
</p></dd>
<dt>&lsquo;<samp>%fp</samp>&rsquo;</dt>
<dd><p>This is &lsquo;<samp>%r10</samp>&rsquo;.
</p></dd>
</dl>


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