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138 lines
6.7 KiB
HTML
138 lines
6.7 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>QNX</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB Installation and Build Guide" />
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<link rel="up" href="build_unix.html" title="Chapter 7. Building Berkeley DB for UNIX/POSIX" />
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<link rel="prev" href="build_unix_macosx.html" title="Mac OS X" />
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<link rel="next" href="build_unix_sco.html" title="SCO" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.3</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">QNX</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="build_unix_macosx.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 7.
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Building Berkeley DB for UNIX/POSIX
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="build_unix_sco.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="build_unix_qnx"></a>QNX</h2>
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</div>
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</div>
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</div>
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<div class="orderedlist">
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<ol type="1">
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<li>
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<span class="bold">
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<strong>To what versions of QNX has DB been ported?</strong>
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</span>
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<p>Berkeley DB has been ported to the QNX Neutrino technology which is commonly
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referred to as QNX RTP (Real-Time Platform). Berkeley DB has not been
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ported to earlier versions of QNX, such as QNX 4.25.</p>
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</li>
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<li>
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<span class="bold">
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<strong>Building Berkeley DB shared libraries fails.</strong>
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</span>
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<p>The <code class="filename">/bin/sh</code> utility distributed with some QNX releases drops
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core when running the GNU libtool script (which is used to build Berkeley DB
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shared libraries). There are two workarounds for this problem: First,
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only build static libraries. You can disable building shared libraries
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by specifying the configuration flag when
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configuring Berkeley DB.</p>
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<p>Second, build Berkeley DB using an alternate shell. QNX distributions include
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an accessories disk with additional tools. One of the included tools
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is the GNU bash shell, which is able to run the libtool script. To
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build Berkeley DB using an alternate shell, move <code class="filename">/bin/sh</code> aside, link
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or copy the alternate shell into that location, configure, build and
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install Berkeley DB, and then replace the original shell utility.</p>
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</li>
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<li>
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<span class="bold">
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<strong>Are there any QNX filesystem issues?</strong>
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</span>
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<p>Berkeley DB generates temporary files for use in transactionally
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protected file system operations. Due to the filename length limit of
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48 characters in the QNX filesystem, applications that are using
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transactions should specify a database name that is at most 43 characters.</p>
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</li>
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<li>
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<span class="bold">
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<strong>What are the implications of QNX's requirement to use
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<code class="literal">shm_open</code>(2) in order to use <code class="literal">mmap</code>(2)?</strong>
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</span>
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<p>QNX requires that files mapped with <code class="literal">mmap</code>(2) be opened using
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<code class="literal">shm_open</code>(2). There are other places in addition to the
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environment shared memory regions, where Berkeley DB tries to memory map files
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if it can.</p>
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<p>The memory pool subsystem normally attempts to use <code class="literal">mmap</code>(2)
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even when using private memory, as indicated by the <a href="../api_reference/C/envopen.html#envopen_DB_PRIVATE" class="olink">DB_PRIVATE</a> flag
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to <a href="../api_reference/C/envopen.html" class="olink">DB_ENV->open()</a>. In the case of QNX, if an application is
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using private memory, Berkeley DB will not attempt to map the memory and will
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instead use the local cache.</p>
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</li>
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<li>
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<span class="bold">
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<strong>What are the implications of QNX's mutex implementation using
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microkernel resources?</strong>
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</span>
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<p>On QNX, the primitives implementing mutexes consume system resources.
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Therefore, if an application unexpectedly fails, those resources could
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leak. Berkeley DB solves this problem by always allocating mutexes in the
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persistent shared memory regions. Then, if an application fails,
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running recovery or explicitly removing the database environment by
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calling the <a href="../api_reference/C/envremove.html" class="olink">DB_ENV->remove()</a> method will allow Berkeley DB to release those
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previously held mutex resources. If an application specifies the
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<a href="../api_reference/C/envopen.html#envopen_DB_PRIVATE" class="olink">DB_PRIVATE</a> flag (choosing not to use persistent shared memory),
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and then fails, mutexes allocated in that private memory may leak their
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underlying system resources. Therefore, the <a href="../api_reference/C/envopen.html#envopen_DB_PRIVATE" class="olink">DB_PRIVATE</a> flag
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should be used with caution on QNX.</p>
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</li>
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<li>
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<span class="bold">
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<strong>The make clean command fails to execute when building the Berkeley DB SQL interface.</strong>
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</span>
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<p>Remove the build directory manually to clean up and proceed. </p>
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</li>
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</ol>
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</div>
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</div>
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<div class="navfooter">
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||
<hr />
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||
<table width="100%" summary="Navigation footer">
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||
<tr>
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||
<td width="40%" align="left"><a accesskey="p" href="build_unix_macosx.html">Prev</a> </td>
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||
<td width="20%" align="center">
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<a accesskey="u" href="build_unix.html">Up</a>
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</td>
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||
<td width="40%" align="right"> <a accesskey="n" href="build_unix_sco.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Mac OS X </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> SCO</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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