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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"> <META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="eCos User Guide" HREF="ecos-user-guide.html"><LINK REL="UP" TITLE="CDL Concepts" HREF="cdl-concepts.html"><LINK REL="PREVIOUS" TITLE="Configuration Items" HREF="cdl-configuration-items.html"><LINK REL="NEXT" TITLE="Templates" HREF="cdl-templates.html"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >eCos User Guide</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="cdl-configuration-items.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 24. CDL Concepts</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="cdl-templates.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="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 <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >requires</I ></SPAN > and <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >active_if</I ></SPAN > attributes [see above]). A violation of consistency rules creates a <SPAN CLASS="emphasis" ><I CLASS="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 <SPAN CLASS="PRODUCTNAME" >eCos</SPAN > tools. Conflicts come in the following flavors:</P ><P ></P ><UL ><LI ><P >An <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >unresolved</I ></SPAN > conflict means that there is a reference to an entity that is not yet in the current configuration </P ></LI ><LI ><P >An <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >illegal value</I ></SPAN > conflict is caused when a configuration item is set to a value that is not permitted (that is, a <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >legal_values</I ></SPAN > goal expression is failing) </P ></LI ><LI ><P >An <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >evaluation exception</I ></SPAN > conflict is caused when the evaluation of an expression would fail (for example, because of a division by zero) </P ></LI ><LI ><P >An <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >unsatisfied goal</I ></SPAN > conflict is caused by a failing <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >requires</I ></SPAN > goal expression </P ></LI ><LI ><P >A <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >bad data</I ></SPAN > conflict arises only rarely, and corresponds to badly constructed CDL. Such a conflict can only be resolved by reference to the CDL writer.</P ></LI ></UL ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="cdl-configuration-items.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ecos-user-guide.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="cdl-templates.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Configuration Items</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="cdl-concepts.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Templates</TD ></TR ></TABLE ></DIV ></BODY ></HTML >
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