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<!-- Copyright (C) 2003 Red Hat, Inc.                                --><!-- This material may be distributed only subject to the terms      --><!-- and conditions set forth in the Open Publication License, v1.0  --><!-- or later (the latest version is presently available at          --><!-- http://www.opencontent.org/openpub/).                           --><!-- Distribution of the work or derivative of the work in any       --><!-- standard (paper) book form is prohibited unless prior           --><!-- permission is obtained from the copyright holder.               --><HTML><HEAD><TITLE>Conflicts</TITLE><meta name="MSSmartTagsPreventParsing" content="TRUE"><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+"><LINKREL="HOME"TITLE="eCos User Guide"HREF="ecos-user-guide.html"><LINKREL="UP"TITLE="CDL Concepts"HREF="cdl-concepts.html"><LINKREL="PREVIOUS"TITLE="Configuration Items"HREF="cdl-configuration-items.html"><LINKREL="NEXT"TITLE="Templates"HREF="cdl-templates.html"></HEAD><BODYCLASS="SECT1"BGCOLOR="#FFFFFF"TEXT="#000000"LINK="#0000FF"VLINK="#840084"ALINK="#0000FF"><DIVCLASS="NAVHEADER"><TABLESUMMARY="Header navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">eCos User Guide</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><AHREF="cdl-configuration-items.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom">Chapter 24. CDL Concepts</TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="cdl-templates.html"ACCESSKEY="N">Next</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="SECT1"><H1CLASS="SECT1"><ANAME="CDL-CONFLICTS">Conflicts</H1><P>Not all settings of configuration items will lead to a	  coherent configuration; for example, the use of a timeout	  facility might require the existence of timer support, so if	  the one is required the other cannot be removed.  Coherence	  is policed by means of consistency rules (in particular, the	  goal expressions that appear as CDL items	  <SPANCLASS="emphasis"><ICLASS="EMPHASIS">requires</I></SPAN> and	  <SPANCLASS="emphasis"><ICLASS="EMPHASIS">active_if</I></SPAN> attributes [see	  above]).  A violation of consistency rules creates a	  <SPANCLASS="emphasis"><ICLASS="EMPHASIS">conflict</I></SPAN>, which must be resolved in	  order to ensure a consistent configuration. Conflict	  resolution can be performed manually or with the assistance	  of the <SPANCLASS="PRODUCTNAME">eCos</SPAN> tools.  Conflicts come in the following	  flavors:</P><P></P><UL><LI><P>An <SPANCLASS="emphasis"><ICLASS="EMPHASIS">unresolved</I></SPAN> conflict means thatthere is a reference to an entity that is not yet in the currentconfiguration </P></LI><LI><P>An <SPANCLASS="emphasis"><ICLASS="EMPHASIS">illegal value</I></SPAN> conflict is causedwhen a configuration item is set to a value that is not permitted(that is, a <SPANCLASS="emphasis"><ICLASS="EMPHASIS">legal_values</I></SPAN> goal expressionis failing) </P></LI><LI><P>An <SPANCLASS="emphasis"><ICLASS="EMPHASIS">evaluation exception</I></SPAN> conflictis caused when the evaluation of an expression would fail (for example,because of a division by zero) </P></LI><LI><P>An <SPANCLASS="emphasis"><ICLASS="EMPHASIS">unsatisfied goal</I></SPAN> conflict is causedby a failing <SPANCLASS="emphasis"><ICLASS="EMPHASIS">requires</I></SPAN> goal expression </P></LI><LI><P>A <SPANCLASS="emphasis"><ICLASS="EMPHASIS">bad data</I></SPAN> conflict arises only rarely,and corresponds to badly constructed CDL.  Such a conflict can onlybe resolved by reference to the CDL writer.</P></LI></UL></DIV><DIVCLASS="NAVFOOTER"><HRALIGN="LEFT"WIDTH="100%"><TABLESUMMARY="Footer navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top"><AHREF="cdl-configuration-items.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="ecos-user-guide.html"ACCESSKEY="H">Home</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top"><AHREF="cdl-templates.html"ACCESSKEY="N">Next</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Configuration Items</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="cdl-concepts.html"ACCESSKEY="U">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">Templates</TD></TR></TABLE></DIV></BODY></HTML>
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