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linux-kernel-module-cheat/9p-vs-nfs.html
Ciro Santilli 0a2a05fe28 8e6cdcb14b
2025-05-10 07:50:53 +01:00

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<meta name="description" content="The perfect emulation setup to study and develop the &lt;&lt;linux-kernel&gt;&gt; v5.9.2, kernel modules, &lt;&lt;qemu-buildroot-setup,QEMU&gt;&gt;, &lt;&lt;gem5-buildroot-setup,gem5&gt;&gt; and x86_64, ARMv7 and ARMv8 &lt;&lt;userland-assembly,userland&gt;&gt; and &lt;&lt;baremetal-setup,baremetal&gt;&gt; assembly, &lt;&lt;c,ANSI C&gt;&gt;, &lt;&lt;cpp,C++&gt;&gt; and &lt;&lt;posix,POSIX&gt;&gt;. EVERYTHING is built from source. &lt;&lt;gdb&gt;&gt; and &lt;&lt;kgdb&gt;&gt; just work. Powered by &lt;&lt;about-the-qemu-buildroot-setup,Buildroot&gt;&gt; and &lt;&lt;about-the-baremetal-setup,crosstool-NG&gt;&gt;. Highly automated. Thoroughly documented. Automated &lt;&lt;test-this-repo,tests&gt;&gt;. "Tested" in an Ubuntu 20.04 host.">
<title>Linux Kernel Module Cheat</title>
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</head>
<body id="9p-vs-nfs" class="article">
<div id="header">
<h1>Linux Kernel Module Cheat</h1>
</div>
<div id="content">
<div class="sect3">
<h4 id="9p-vs-nfs"><a class="anchor" href="#9p-vs-nfs"></a><a class="link" href="#9p-vs-nfs">15.4.1. 9P vs NFS</a></h4>
<div class="paragraph">
<p>All of 9P and NFS (and sshfs) allow sharing directories between guest and host.</p>
</div>
<div class="paragraph">
<p>Advantages of 9P</p>
</div>
<div class="ulist">
<ul>
<li>
<p>doesn&#8217;t require <code>sudo</code> on the host to mount</p>
</li>
<li>
<p>we could share a guest directory to the host, but this would require running a server on the guest, which adds <a href="resource-tradeoff-guidelines.html">simulation overhead</a></p>
<div class="paragraph">
<p>Furthermore, this would be inconvenient, since what we usually want to do is to share host cross built files with the guest, and to do that we would have to copy the files over after the guest starts the server.</p>
</div>
</li>
<li>
<p>QEMU implements 9P natively, which makes it very stable and convenient, and must mean it is a simpler protocol than NFS as one would expect.</p>
<div class="paragraph">
<p>This is not the case for gem5 7bfb7f3a43f382eb49853f47b140bfd6caad0fb8 unfortunately, which relies on the <a href="https://github.com/chaos/diod">diod</a> host daemon, although it is not unfeasible that future versions could implement it natively as well.</p>
</div>
</li>
</ul>
</div>
<div class="paragraph">
<p>Advantages of NFS:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>way more widely used and therefore stable and available, not to mention that it also works on real hardware.</p>
</li>
<li>
<p>the name does not start with a digit, which is an invalid identifier in all programming languages known to man. Who in their right mind would call a software project as such? It does not even match the natural order of Plan 9; Plan then 9: P9!</p>
</li>
</ul>
</div>
<div class="ulist">
<ul>
</ul>
</div>
</div>
<div class="paragraph nav-footer">
<p> Up: <a href="9p.html">9P</a> | ⌂ Home: <a href="README.html">Linux Kernel Module Cheat</a> | Next: <a href="9p-getting-started.html">9P getting started</a> →</p>
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