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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 >Updating the ecos.db database</TITLE ><meta name="MSSmartTagsPreventParsing" content="TRUE"> <META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="The eCos Component Writer's Guide" HREF="cdl-guide.html"><LINK REL="UP" TITLE="The CDL Language" HREF="language.html"><LINK REL="PREVIOUS" TITLE="Interfaces" HREF="language.interface.html"><LINK REL="NEXT" TITLE="The Build Process" HREF="build.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" >The <SPAN CLASS="APPLICATION" >eCos</SPAN > Component Writer's Guide</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="language.interface.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 3. The CDL Language</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="build.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="LANGUAGE.DATABASE">Updating the <SPAN CLASS="DATABASE" >ecos.db</SPAN > database</H1 ><P >The current implementation of the component framework requires that all packages be present in a single component repository and listed in that repository's <SPAN CLASS="DATABASE" >ecos.db</SPAN > database. This is not generally a problem for application developers who can consider the component repository a read-only resource, except when adding or removing packages via the administration tool. However it means that component writers need to do their development work inside a component repository as well, and update the database with details of their new package or packages. Future enhancements to the component framework may allow new components to be developed outside a repository. </P ><P >Like most files related to the component framework, the <SPAN CLASS="DATABASE" >ecos.db</SPAN > database is actually a <SPAN CLASS="APPLICATION" >Tcl</SPAN > script. Typical package entries would look like this:</P ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="PROGRAMLISTING" >package CYGPKG_LIBC { alias { "C library" libc clib clibrary } directory language/c/libc script libc.cdl description " This package enables compatibility with the ISO C standard - ISO/IEC 9899:1990. This allows the user application to use well known standard C library functions, and in eCos starts a thread to invoke the user function main()" } package CYGPKG_IO_PCI { alias { "PCI configuration library" io_pci } directory io/pci script io_pci.cdl hardware description " This package contains the PCI configuration library." }</PRE ></TD ></TR ></TABLE ><P >The <TT CLASS="LITERAL" >package</TT > command takes two arguments, a name and a body. The name must be the same as in the <TT CLASS="LITERAL" >cdl_package</TT > command in the package's top-level <SPAN CLASS="APPLICATION" >CDL</SPAN > script. The body can contain the following five commands: <TT CLASS="LITERAL" >alias</TT >, <TT CLASS="LITERAL" >directory</TT >, <TT CLASS="LITERAL" >script</TT >, <TT CLASS="LITERAL" >hardware</TT > and <TT CLASS="LITERAL" >description</TT >.</P ><P ></P ><DIV CLASS="VARIABLELIST" ><DL ><DT ><TT CLASS="LITERAL" >alias</TT ></DT ><DD ><P >Each package should have one or more aliases. The first alias is typically used when listing the known packages, because a string like <TT CLASS="LITERAL" >C library</TT > is a bit easier to read and understand than <TT CLASS="VARNAME" >CYGPKG_LIBC</TT >. The other aliases are not used for output, but are accepted on input. For example the <SPAN CLASS="APPLICATION" >ecosconfig</SPAN > command-line tool will accept <TT CLASS="LITERAL" >add libc</TT > as an option, as well as <TT CLASS="LITERAL" >add CYGPKG_LIBC</TT >.</P ></DD ><DT ><TT CLASS="LITERAL" >directory</TT ></DT ><DD ><P >This is used to specify the location of the package relative to the root of the component repository. It should be noted that in the current component framework this location cannot be changed in subsequent releases of the package: if for some reason it is desirable to install a new release elsewhere in the repository, all the old versions must first be uninstalled; the database cannot hold two separate locations for one package.</P ></DD ><DT ><TT CLASS="LITERAL" >script</TT ></DT ><DD ><P >The <TT CLASS="LITERAL" >script</TT > command specifies the location of the package's top-level <SPAN CLASS="APPLICATION" >CDL</SPAN > script, in other words the one containing the <TT CLASS="LITERAL" >cdl_package</TT > definition. If the package follows the <A HREF="package.html#PACKAGE.HIERARCHY" >directory layout conventions</A > then this script will be in the <TT CLASS="FILENAME" >cdl</TT > sub-directory, otherwise it will be relative to the package's top-level directory. Again once a release has been made this file should not change in later releases. In practice the top-level script is generally named after the package itself, so changing its name is unlikely to be useful. </P ></DD ><DT ><TT CLASS="LITERAL" >hardware</TT ></DT ><DD ><P >Packages which are tied to specific hardware, for example device drivers and HAL packages, should indicate this in both the <TT CLASS="LITERAL" >cdl_package</TT > command of the <SPAN CLASS="APPLICATION" >CDL</SPAN > script and in the database entry.</P ></DD ><DT ><TT CLASS="LITERAL" >description</TT ></DT ><DD ><P >This should give a brief description of the package. Typically the text for the <SPAN CLASS="PROPERTY" >description</SPAN > property in the <TT CLASS="LITERAL" >cdl_package</TT > command will be re-used.</P ></DD ></DL ></DIV ><DIV CLASS="NOTE" ><BLOCKQUOTE CLASS="NOTE" ><P ><B >Note: </B >Most of the information in the <SPAN CLASS="DATABASE" >ecos.db</SPAN > file could be obtained by a relatively simple utility. This would be passed a single argument identifying a package's top-level <SPAN CLASS="APPLICATION" >CDL</SPAN > script. The directory path relative to the component repository root could be determined from the filename. The name, <TT CLASS="LITERAL" >description</TT > and <TT CLASS="LITERAL" >hardware</TT > fields could be obtained from the script's <TT CLASS="LITERAL" >cdl_package</TT > command. The <SPAN CLASS="PROPERTY" >display</SPAN > property would supply the first alias, additional aliases could be obtained by extending the syntax of that property or by other means. Something along these lines may be provided by a future release of the component framework.</P ></BLOCKQUOTE ></DIV ><P >Currently the <SPAN CLASS="DATABASE" >ecos.db</SPAN > database also holds information about the various targets. When porting to a new target it will be necessary to add information about the target to the database, as well as the details of the new platform HAL package and any related packages. </P ></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="language.interface.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="cdl-guide.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="build.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Interfaces</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="language.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >The Build Process</TD ></TR ></TABLE ></DIV ></BODY ></HTML >
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