2007-10-19 11:52:02 +02:00
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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2007-10-30 13:51:21 +01:00
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<!-- (c) Benjamin Krill <ben@codiert.org> -->
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2007-10-19 11:52:02 +02:00
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<head>
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<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
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<title>FPGA Filesystem</title>
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<style type="text/css" media="all">@import "f.css";</style>
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</head>
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<body>
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<div id="headspace">
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<div id="header">
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<a href="#top" title="Top">Top</a> :
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<a href="#concept" title="Concepts">Concept</a> :
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<a href="#download" title="Download">Download</a> :
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<a href="#contact" title="Contact">Contact</a>
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</div>
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</div>
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<div id="logo">
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<img src="img/fpgafs.png" alt="FPGAFS" />
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</div>
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<div id="content">
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2007-10-19 12:14:02 +02:00
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<a name="top" id="top"></a>
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<div id="conspace"> </div>
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<h1>FPGAFS</h1>
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2007-10-19 11:52:02 +02:00
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<p>It provides a framework for a high performance reconfigurable computer
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environment. The abstraction between the reconfigurable device and the
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user application is simplified by using a virtual filesystem and a thread
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abstraction per device context.<br/>
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FPGAFS consists of two major layers of abstraction. First, the directory
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representation to the user application. This interface provides for each context
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one directory with a specified content to transfer data. The second layer
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provides an interface for low level driver. It gives the flexibility to register
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a lot of different low level drivers for different accelerators which can be
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operate at the same time in one target system.</p>
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<h2 class="title">Concept</h2><a name="concept" id="concept"></a>
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2007-10-30 13:36:07 +01:00
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<h2 class="subtitle">Overall Design</h2>
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<p>As the name already mentioned the project provides a virtual filesystem for the
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operating system. The filesystem abstrect each each reconfigurable part inside a
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host system or inside one chip by a directory. The permissions of the files can
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provide access control for different users. The following listing shows the directory
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entries which will be created. These entries can be seen as the assigned context to
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the FPGA interface:</p>
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<ul>
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<li>/fpgafs/example/cmd: write only file, this is the interface to send
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defined commands to the context.</li>
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<li>/fpgafs/example/stat: read only file, from which the context's status
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can be received.</li>
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<li>/fpgafs/example/din: write only file, sends data to the reconfigurable
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device.</li>
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<li>/fpgafs/example/dout: read only file, receives calculated data from
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the device.</li>
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<li>/fpgafs/example/load: write only file, writes data which should be
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loaded onto the reconfigurable device.</li>
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<li>/fpgafs/foobar/lldrv: write only file, selects the low level driver
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which should be used.</li>
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</ul>
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<p>
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In general, the complete framework provides a generic interface to the userspace
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and a flexible and changeable interface to the hardware. Figure 1 shows the design of
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the framework. At the bottom, there are low level drivers which must be registered on
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the main FPGAFS. On top of the low-level drivers, different contexts are shown
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which are represented by directories.</p>
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<div class="center">
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<img class="border" src="img/design_overall.png" alt="overall design" />
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</div>
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<h2 class="subtitle">Low Level Driver</h2>
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<p>All low level drivers implement an interface which will be used by more generalized
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functions from the low level management. The structure "fpgafs_lldrv" provides at least
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the defined function pointers. Each low level driver can be loaded and unloaded as a
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common Linux module. The init function of each low level driver has to call the
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registration function of the FPGAFS low level management module. At unloading the module
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the unregistration function will be called. With this concept different hardware
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accelerators can be supported and each low level driver can implement its own
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communication functions. So each low level driver brings its own programming routine
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for the accelerator. This gives the possibility to create accelerators that can handle
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more than one application at once. For example, the accelerator can reprogram parts of
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the accelerator and can be used without reconfiguring the whole accelerator. However,
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this functionality totally depends on the underlying hardware and the programming
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mechanism. But the framework will support such and other functionalities because of
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the flexible layer concept.</p><br />
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<p>More documentation can be found in the repository and can be enquired (see Contact).</p>
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2007-10-19 11:52:02 +02:00
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<h2 class="title">Download</h2><a name="download" id="download"></a>
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FPGAFS keeps its development tree in a Subversion repository. It can be
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2007-10-30 13:36:07 +01:00
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downloaded with a Subversion checkout. The repository is anonymously accessible. <br /><br />
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2007-10-22 15:24:55 +02:00
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<h2 class="consol">$ svn co https://svn.subgra.de/ben/projects/fpgafs</h2>
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2007-10-19 11:52:02 +02:00
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<h2 class="title">Contact</h2><a name="contact" id="contact"></a>
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2007-10-30 13:36:07 +01:00
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<p>Benjamin Krill: ben@codiert.org</p>
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2007-10-30 13:51:21 +01:00
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<h2 class="footer">ID: $Id$</h3>
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2007-10-19 11:52:02 +02:00
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</div>
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</body>
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</html>
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