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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><link rel="STYLESHEET" type="text/css" href="wrs.css"><title> Virtual Memory Interface </title></head><body bgcolor="FFFFFF"><p class="navbar" align="right"><a href="index.html"><img border="0" alt="[Contents]" src="icons/contents.gif"></a><a href="GuideIX.html"><img border="0" alt="[Index]" src="icons/index.gif"></a><a href="c-vm.html"><img border="0" alt="[Top]" src="icons/top.gif"></a><a href="c-vm1.html"><img border="0" alt="[Prev]" src="icons/prev.gif"></a><a href="c-vm3.html"><img border="0" alt="[Next]" src="icons/next.gif"></a></p><font face="Helvetica, sans-serif" class="sans"><h3 class="H2"><i><a name="84383">7.2 Basic Virtual Memory Support</a></i></h3></font><dl class="margin"><dl class="margin"><dd><p class="Body"><a name="84385"> </a>For systems with an MMU, VxWorks allows you to perform DMA and interprocessor communication more efficiently by rendering related buffers noncacheable. This is necessary to ensure that data is not being buffered locally when other processors or DMA devices are accessing the same memory location. Without the ability to make portions of memory noncacheable, caching must be turned off globally (resulting in performance degradation) or buffers must be flushed/invalidated manually. </p><dd><p class="Body"><a name="84386"> </a>Basic virtual memory support is included by selecting <b class="symbol_UC">INCLUDE_MMU_BASIC</b> in the project facility VxWorks view; see <a href="c-vm3.html#84391"><i class="title">7.3 Virtual Memory Configuration</i></a>. It is also possible to allocate noncacheable buffers using <b class="routine"><i class="routine">cacheDmaMalloc</i></b><b>(</b> <b>)</b>; see the reference entry for <b class="library">cacheLib</b>.</p></dl></dl><a name="foot"><hr></a><p class="navbar" align="right"><a href="index.html"><img border="0" alt="[Contents]" src="icons/contents.gif"></a><a href="GuideIX.html"><img border="0" alt="[Index]" src="icons/index.gif"></a><a href="c-vm.html"><img border="0" alt="[Top]" src="icons/top.gif"></a><a href="c-vm1.html"><img border="0" alt="[Prev]" src="icons/prev.gif"></a><a href="c-vm3.html"><img border="0" alt="[Next]" src="icons/next.gif"></a></p></body></html><!---by WRS Documentation (), Wind River Systems, Inc. conversion tool: Quadralay WebWorks Publisher 4.0.11 template: CSS Template, Jan 1998 - Jefro --->⌨️ 快捷键说明
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