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<!-- Copyright (C) 2003 Red Hat, Inc. -->
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<!-- This material may be distributed only subject to the terms -->
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<!-- and conditions set forth in the Open Publication License, v1.0 -->
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<!-- http://www.opencontent.org/openpub/). -->
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<!-- Distribution of the work or derivative of the work in any -->
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<!-- standard (paper) book form is prohibited unless prior -->
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<!-- permission is obtained from the copyright holder. -->
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<HTML
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><HEAD
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><TITLE
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>Editing an eCos Savefile</TITLE
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><meta name="MSSmartTagsPreventParsing" content="TRUE">
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<META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
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"><LINK
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REL="HOME"
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TITLE="eCos User Guide"
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HREF="ecos-user-guide.html"><LINK
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REL="UP"
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TITLE="Manual Configuration"
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HREF="manual-configuration.html"><LINK
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REL="PREVIOUS"
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TITLE="Fine-grained Configuration"
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HREF="fine-grained-configuration.html"><LINK
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REL="NEXT"
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TITLE="Editing the Sources"
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HREF="editing-the-sources.html"></HEAD
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><BODY
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>eCos User Guide</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="fine-grained-configuration.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 28. Manual Configuration</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="editing-the-sources.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="EDITING-AN-ECOS-SAVEFILE">Editing an <SPAN
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CLASS="PRODUCTNAME"
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>eCos</SPAN
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> Savefile</H1
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><P
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>The <SPAN
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CLASS="PRODUCTNAME"
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>eCos</SPAN
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> configuration information is held in a single
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savefile, typically <TT
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CLASS="FILENAME"
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>ecos.ecc</TT
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>, which can
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be generated by either the GUI configuration tool or by the
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command line <B
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CLASS="COMMAND"
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>ecosconfig</B
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> tool. The file
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normally exists at the top level of the build tree. It is a
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text file, allowing the various configurations options to be
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edited inside a suitable text editor or by other programs or
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scripts, as well as in the GUI config tool.</P
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><P
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>An <SPAN
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CLASS="PRODUCTNAME"
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>eCos</SPAN
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> savefile is actually a script in the <SPAN
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CLASS="emphasis"
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><I
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CLASS="EMPHASIS"
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>Tcl</I
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></SPAN
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> programming
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language, so any modifications to the file need to preserve Tcl
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syntax. For most configuration options, any modifications will be
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trivial and there is no need to worry about Tcl syntax. For example,
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changing a 1 to a 0 to disable an option. For more complicated
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options, for example<TT
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CLASS="LITERAL"
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> CYGDAT_UITRON_TASK_EXTERNS</TT
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>,
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which involves some lines of C code, more care has
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to be taken. If an edited savefile is no longer a valid Tcl script
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then the configuration tools will be unable to read back the data
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for further processing, for example to generate a build tree. An
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outline of Tcl syntax is given below. One point worth noting here
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is that a line that begins with a “#” is
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usually a comment, and the bulk of an <SPAN
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CLASS="PRODUCTNAME"
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>eCos</SPAN
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> savefile actually consists
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of such comments, to make it easier to edit.</P
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="AEN2721">Header</H2
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><P
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>An <SPAN
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CLASS="PRODUCTNAME"
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>eCos</SPAN
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> savefile begins with a header, which typically
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looks something like this:</P
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><TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
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><PRE
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CLASS="SCREEN"
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># eCos saved configuration
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# ---- commands --------------------------------------------------------
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# This section contains information about the savefile format.
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# It should not be edited. Any modifications made to this section
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# may make it impossible for the configuration tools to read
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# the savefile.
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cdl_savefile_version 1;
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cdl_savefile_command cdl_savefile_version {};
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cdl_savefile_command cdl_savefile_command {};
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cdl_savefile_command
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cdl_configuration { description hardware template package };
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cdl_savefile_command cdl_package { value_source user_value wizard_value inferred_value };
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cdl_savefile_command cdl_component { value_source user_value wizard_value inferred_value };
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cdl_savefile_command cdl_option { value_source user_value wizard_value inferred_value };
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cdl_savefile_command cdl_interface { value_source user_value wizard_value inferred_value };
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</PRE
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></TD
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></TR
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></TABLE
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><P
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>This section of the savefile is intended for use by the
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configuration system, and should not be edited. If this
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section is edited then the various configuration tools may no
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longer be able to read in the modified savefile.</P
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></DIV
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
|
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><A
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|
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NAME="AEN2727">Toplevel Section</H2
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><P
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>The header is followed by a section that defines the
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configuration as a whole. A typical example would
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be:</P
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><TABLE
|
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BORDER="5"
|
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BGCOLOR="#E0E0F0"
|
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WIDTH="70%"
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><TR
|
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><TD
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><PRE
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CLASS="SCREEN"
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># ---- toplevel --------------------------------------------------------
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# This section defines the toplevel configuration object. The only
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# values that can be changed are the name of the configuration and
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# the description field. It is not possible to modify the target,
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# the template or the set of packages simply by editing the lines
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# below because these changes have wide-ranging effects. Instead
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# the appropriate tools should be used to make such modifications.
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cdl_configuration eCos {
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description ““ ;
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|
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# These fields should not be modified.
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hardware pid ;
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template uitron ;
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package -hardware CYGPKG_HAL_ARM current ;
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package -hardware CYGPKG_HAL_ARM_PID current ;
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package -hardware CYGPKG_IO_SERIAL current ;
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package -template CYGPKG_HAL current ;
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package -template CYGPKG_IO current ;
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package -template CYGPKG_INFRA current ;
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package -template CYGPKG_KERNEL current ;
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package -template CYGPKG_UITRON current ;
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package -template CYGPKG_LIBC current ;
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package -template CYGPKG_LIBM current ;
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package -template CYGPKG_DEVICES_WALLCLOCK current ;
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package -template CYGPKG_ERROR current ;
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};
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</PRE
|
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|
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></TD
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|
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></TR
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></TABLE
|
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><P
|
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>This section allows the configuration tools to reload the
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various packages that make up the configuration. Most of the information
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should not be edited. If it is necessary to add a new package or
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to remove an existing one then the appropriate tools should be used
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for this, for example:</P
|
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><TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
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|
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><PRE
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CLASS="PROGRAMLISTING"
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|
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>$ ecosconfig remove CYGPKG_LIBM</PRE
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|
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></TD
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|
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></TR
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|
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></TABLE
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><P
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>There are two fields which can be edited. Configurations have
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a name; in this case <SPAN
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CLASS="PRODUCTNAME"
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>eCos</SPAN
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>. They can also have a description, which
|
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is some arbitrary text. The configuration tools do not make use
|
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of these fields, they exist so that users can store additional information
|
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about a configuration.</P
|
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></DIV
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><DIV
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CLASS="SECT2"
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><H2
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CLASS="SECT2"
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><A
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NAME="AEN2735">Conflicts Section</H2
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><P
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>The toplevel section is followed by details of all the
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conflicts (if any) in the configuration, for
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example:</P
|
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><TABLE
|
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
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><PRE
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CLASS="SCREEN"
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># ---- conflicts -------------------------------------------------------
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# There are 2 conflicts.
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#
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# option CYGNUM_LIBC_TIME_DST_DEFAULT_OFFSET
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# Property LegalValues
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# Illegal current value 100000
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# Legal values are: -90000 to 90000
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#
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# option CYGSEM_LIBC_TIME_CLOCK_WORKING
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# Property Requires
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# Requires constraint not satisfied: CYGFUN_KERNEL_THREADS_TIMER
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</PRE
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|
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></TD
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|
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></TR
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></TABLE
|
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><P
|
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>When editing a configuration you may end up with something
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that is invalid. Any problems in the configuration will be reported
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in the conflicts section. In this case there are two conflicts.
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The option <TT
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CLASS="LITERAL"
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>CYGNUM_LIBC_TIME_DST_DEFAULT_OFFSET</TT
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> has
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been given an illegal value: typically this would be fixed by searching
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for the definition of that option later on in the savefile and modifying
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the value. The second conflict is more interesting, an unsatisfied <SPAN
|
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CLASS="emphasis"
|
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><I
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CLASS="EMPHASIS"
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>requires</I
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></SPAN
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> constraint.
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Configuration options are not independent: disabling some functionality
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in, say, the kernel, can have an impact elsewhere; in this case
|
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the C library. The various dependencies between the options are
|
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specified by the component developers and checked by the configuration
|
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system. In this case there are two obvious ways in which the conflict could
|
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be resolved: re-enabling <TT
|
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CLASS="LITERAL"
|
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>CYGFUN_KERNEL_THREADS_TIMER</TT
|
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>,
|
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|
or disabling <TT
|
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|
|
CLASS="LITERAL"
|
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|
|
>CYGSEM_LIBC_TIME_CLOCK_WORKING</TT
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>.
|
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Both of these options will be listed later on in the file.</P
|
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|
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><P
|
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>Some care has to be taken when modifying configuration options,
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to avoid introducing new conflict. For instance it is possible that
|
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there might be other options in the system which have a dependency
|
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|
|
on <TT
|
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|
|
CLASS="LITERAL"
|
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|
|
>CYGSEM_LIBC_TIME_CLOCK_WORKING</TT
|
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|
>,
|
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so disabling that option may not be the best way to resolve the
|
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|
conflict. Details of all such dependencies are provided in the appropriate
|
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places in the savefile.</P
|
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|
|
><P
|
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|
|
>It is not absolutely required that a configuration be conflict-free
|
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|
|
before generating a build tree and building <SPAN
|
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|
|
CLASS="PRODUCTNAME"
|
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|
|
>eCos</SPAN
|
340 |
|
|
>. It is up to the
|
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|
|
developers of each component to decide what would happen if an attempt
|
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|
|
is made to build <SPAN
|
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|
|
CLASS="PRODUCTNAME"
|
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|
|
>eCos</SPAN
|
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|
|
> while there are still conflicts. In serious
|
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|
|
cases there is likely to be a compile-time failure, or possibly
|
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|
|
a link-time failure. In less serious cases the system may build
|
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|
|
happily and the application can be linked with the resulting library,
|
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|
but the component may not quite function as intended - although
|
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|
it may still be good enough for the specific needs of the application.
|
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|
|
It is also possible that everything builds and links, but once in
|
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|
a while the system will unaccountably crash. Using a configuration
|
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|
that still has conflicts is done entirely at the user’s
|
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|
risk.</P
|
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|
|
></DIV
|
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|
|
><DIV
|
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|
|
CLASS="SECT2"
|
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|
|
><H2
|
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|
|
CLASS="SECT2"
|
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|
|
><A
|
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|
|
NAME="AEN2749">Data Section</H2
|
362 |
|
|
><P
|
363 |
|
|
>The bulk of the savefile lists the various packages,
|
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|
components, and options, including their values and the
|
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|
various dependencies. A number of global options come
|
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|
first, especially those related to the build process such
|
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|
as compiler flags. These are followed by the various
|
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|
|
packages, and the components and options within those
|
369 |
|
|
packages, in order.</P
|
370 |
|
|
><P
|
371 |
|
|
>Packages, components and options are organized in a
|
372 |
|
|
hierarchy. If a particular component is disabled then all
|
373 |
|
|
options and sub-components below it will be inactive: any
|
374 |
|
|
changes made to these will have no effect. The savefile
|
375 |
|
|
contains information about the hierarchy in the form of
|
376 |
|
|
comments, for example:</P
|
377 |
|
|
><TABLE
|
378 |
|
|
BORDER="5"
|
379 |
|
|
BGCOLOR="#E0E0F0"
|
380 |
|
|
WIDTH="70%"
|
381 |
|
|
><TR
|
382 |
|
|
><TD
|
383 |
|
|
><PRE
|
384 |
|
|
CLASS="SCREEN"
|
385 |
|
|
>cdl_package CYGPKG_KERNEL ...
|
386 |
|
|
# >
|
387 |
|
|
cdl_component CYGPKG_KERNEL_EXCEPTIONS ...
|
388 |
|
|
# >
|
389 |
|
|
cdl_option CYGSEM_KERNEL_EXCEPTIONS_DECODE ...
|
390 |
|
|
cdl_option CYGSEM_KERNEL_EXCEPTIONS_GLOBAL ...
|
391 |
|
|
# <
|
392 |
|
|
cdl_component CYGPKG_KERNEL_SCHED ...
|
393 |
|
|
# >
|
394 |
|
|
cdl_option CYGSEM_KERNEL_SCHED_MLQUEUE ...
|
395 |
|
|
cdl_option CYGSEM_KERNEL_SCHED_BITMAP ...
|
396 |
|
|
# <
|
397 |
|
|
# <
|
398 |
|
|
</PRE
|
399 |
|
|
></TD
|
400 |
|
|
></TR
|
401 |
|
|
></TABLE
|
402 |
|
|
><P
|
403 |
|
|
>This corresponds to the following hierarchy:</P
|
404 |
|
|
><TABLE
|
405 |
|
|
BORDER="5"
|
406 |
|
|
BGCOLOR="#E0E0F0"
|
407 |
|
|
WIDTH="70%"
|
408 |
|
|
><TR
|
409 |
|
|
><TD
|
410 |
|
|
><PRE
|
411 |
|
|
CLASS="SCREEN"
|
412 |
|
|
> CYGPKG_KERNEL
|
413 |
|
|
CYGPKG_KERNEL_EXCEPTIONS
|
414 |
|
|
CYGSEM_KERNEL_EXCEPTIONS_DECODE
|
415 |
|
|
CYGSEM_KERNEL_EXCEPTIONS_GLOBAL
|
416 |
|
|
CYGPKG_KERNEL_SCHED
|
417 |
|
|
CYGSEM_KERNEL_SCHED_MLQUEUE
|
418 |
|
|
CYGSEM_KERNEL_SCHED_BITMAP
|
419 |
|
|
</PRE
|
420 |
|
|
></TD
|
421 |
|
|
></TR
|
422 |
|
|
></TABLE
|
423 |
|
|
><P
|
424 |
|
|
>Providing the hierarchy information in this way allows
|
425 |
|
|
programs or scripts to analyze the savefile and readily
|
426 |
|
|
determine the hierarchy. It could also be used by a
|
427 |
|
|
sufficiently powerful editor to support structured editing
|
428 |
|
|
of <SPAN
|
429 |
|
|
CLASS="PRODUCTNAME"
|
430 |
|
|
>eCos</SPAN
|
431 |
|
|
> savefiles. The information is not used by the
|
432 |
|
|
configuration tools themselves since they obtain the
|
433 |
|
|
hierarchy from the original CDL scripts.</P
|
434 |
|
|
><P
|
435 |
|
|
>Each configurable entity is preceded by a comment, of
|
436 |
|
|
the following form:</P
|
437 |
|
|
><TABLE
|
438 |
|
|
BORDER="5"
|
439 |
|
|
BGCOLOR="#E0E0F0"
|
440 |
|
|
WIDTH="70%"
|
441 |
|
|
><TR
|
442 |
|
|
><TD
|
443 |
|
|
><PRE
|
444 |
|
|
CLASS="SCREEN"
|
445 |
|
|
># Kernel schedulers
|
446 |
|
|
# doc: ref/ecos-ref/ecos-kernel-overview.html#THE-SCHEDULER
|
447 |
|
|
# The eCos kernel provides a choice of schedulers. In addition
|
448 |
|
|
# there are a number of configuration options to control the
|
449 |
|
|
# detailed behaviour of these schedulers.
|
450 |
|
|
cdl_component CYGPKG_KERNEL_SCHED {
|
451 |
|
|
...
|
452 |
|
|
};
|
453 |
|
|
</PRE
|
454 |
|
|
></TD
|
455 |
|
|
></TR
|
456 |
|
|
></TABLE
|
457 |
|
|
><P
|
458 |
|
|
>This provides a short textual alias
|
459 |
|
|
<TT
|
460 |
|
|
CLASS="LITERAL"
|
461 |
|
|
>Kernel schedulers</TT
|
462 |
|
|
> for the
|
463 |
|
|
component. If online documentation is available for the
|
464 |
|
|
configurable entity then this will come next. Finally
|
465 |
|
|
there is a short description of the entity as a whole. All
|
466 |
|
|
this information is provided by the component
|
467 |
|
|
developers.</P
|
468 |
|
|
><P
|
469 |
|
|
>Each configurable entity takes the form:</P
|
470 |
|
|
><TABLE
|
471 |
|
|
BORDER="5"
|
472 |
|
|
BGCOLOR="#E0E0F0"
|
473 |
|
|
WIDTH="70%"
|
474 |
|
|
><TR
|
475 |
|
|
><TD
|
476 |
|
|
><PRE
|
477 |
|
|
CLASS="SCREEN"
|
478 |
|
|
><type> <name> {
|
479 |
|
|
<data>
|
480 |
|
|
};</PRE
|
481 |
|
|
></TD
|
482 |
|
|
></TR
|
483 |
|
|
></TABLE
|
484 |
|
|
><P
|
485 |
|
|
>Configurable entities may not be active. This can be either
|
486 |
|
|
because the parent is disabled or inactive, or because there are
|
487 |
|
|
one or more <SPAN
|
488 |
|
|
CLASS="emphasis"
|
489 |
|
|
><I
|
490 |
|
|
CLASS="EMPHASIS"
|
491 |
|
|
>active_if</I
|
492 |
|
|
></SPAN
|
493 |
|
|
> properties. Modifying
|
494 |
|
|
the value of an inactive entity has no effect on the configuration,
|
495 |
|
|
so this information is provided first:</P
|
496 |
|
|
><P
|
497 |
|
|
></P
|
498 |
|
|
><TABLE
|
499 |
|
|
BORDER="5"
|
500 |
|
|
BGCOLOR="#E0E0F0"
|
501 |
|
|
WIDTH="70%"
|
502 |
|
|
><TR
|
503 |
|
|
><TD
|
504 |
|
|
><PRE
|
505 |
|
|
CLASS="SCREEN"
|
506 |
|
|
>cdl_option CYGSEM_KERNEL_EXCEPTIONS_DECODE {
|
507 |
|
|
# This option is not active
|
508 |
|
|
# The parent CYGPKG_KERNEL_EXCEPTIONS is disabled
|
509 |
|
|
...
|
510 |
|
|
};
|
511 |
|
|
|
512 |
|
|
...
|
513 |
|
|
|
514 |
|
|
cdl_option CYGIMP_IDLE_THREAD_YIELD {
|
515 |
|
|
# This option is not active
|
516 |
|
|
# ActiveIf constraint: (CYGNUM_KERNEL_SCHED_PRIORITIES == 1)
|
517 |
|
|
# CYGNUM_KERNEL_SCHED_PRIORITIES == 32
|
518 |
|
|
# --> 0
|
519 |
|
|
...
|
520 |
|
|
}; </PRE
|
521 |
|
|
></TD
|
522 |
|
|
></TR
|
523 |
|
|
></TABLE
|
524 |
|
|
><P
|
525 |
|
|
>For <TT
|
526 |
|
|
CLASS="LITERAL"
|
527 |
|
|
>CYGIMP_IDLE_THREAD_YIELD</TT
|
528 |
|
|
> the
|
529 |
|
|
savefile lists the expression that must be satisfied if the option
|
530 |
|
|
is to be active, followed by the current value of all entities that
|
531 |
|
|
are referenced in the expression, and finally the result of evaluating
|
532 |
|
|
that expression.</P
|
533 |
|
|
><P
|
534 |
|
|
>Not all options are directly modifiable in the savefile. First,
|
535 |
|
|
the value of packages (which is the version of that package loaded
|
536 |
|
|
into the configuration) cannot be modified here.</P
|
537 |
|
|
><TABLE
|
538 |
|
|
BORDER="5"
|
539 |
|
|
BGCOLOR="#E0E0F0"
|
540 |
|
|
WIDTH="70%"
|
541 |
|
|
><TR
|
542 |
|
|
><TD
|
543 |
|
|
><PRE
|
544 |
|
|
CLASS="SCREEN"
|
545 |
|
|
> cdl_package CYGPKG_KERNEL {
|
546 |
|
|
# Packages cannot be added or removed, nor can their version be changed,
|
547 |
|
|
# simply by editing their value. Instead the appropriate configuration
|
548 |
|
|
# should be used to perform these actions.
|
549 |
|
|
...
|
550 |
|
|
}; </PRE
|
551 |
|
|
></TD
|
552 |
|
|
></TR
|
553 |
|
|
></TABLE
|
554 |
|
|
><P
|
555 |
|
|
>The version of a package can be changed using e.g.: </P
|
556 |
|
|
><TABLE
|
557 |
|
|
BORDER="5"
|
558 |
|
|
BGCOLOR="#E0E0F0"
|
559 |
|
|
WIDTH="70%"
|
560 |
|
|
><TR
|
561 |
|
|
><TD
|
562 |
|
|
><PRE
|
563 |
|
|
CLASS="SCREEN"
|
564 |
|
|
>$ ecosconfig version 1.3 CYGPKG_KERNEL</PRE
|
565 |
|
|
></TD
|
566 |
|
|
></TR
|
567 |
|
|
></TABLE
|
568 |
|
|
><P
|
569 |
|
|
>Even though a package’s value cannot be modified
|
570 |
|
|
here, it is still important for the savefile to contain the details.
|
571 |
|
|
In particular packages may impose constraints on other configurable
|
572 |
|
|
entities and may be referenced by other configurable entities. Also
|
573 |
|
|
it would be difficult to understand or extract the configuration’s
|
574 |
|
|
hierarchy if the packages were not listed in the appropriate places
|
575 |
|
|
in the savefile.</P
|
576 |
|
|
><P
|
577 |
|
|
>Some components (or, conceivably, options) do not have any
|
578 |
|
|
associated data. Typically they serve only to introduce another
|
579 |
|
|
level in the hierarchy, which can be useful in the context of the
|
580 |
|
|
GUI configuration tool.</P
|
581 |
|
|
><TABLE
|
582 |
|
|
BORDER="5"
|
583 |
|
|
BGCOLOR="#E0E0F0"
|
584 |
|
|
WIDTH="70%"
|
585 |
|
|
><TR
|
586 |
|
|
><TD
|
587 |
|
|
><PRE
|
588 |
|
|
CLASS="SCREEN"
|
589 |
|
|
> cdl_component CYGPKG_HAL_COMMON_INTERRUPTS {
|
590 |
|
|
# There is no associated value.
|
591 |
|
|
}; </PRE
|
592 |
|
|
></TD
|
593 |
|
|
></TR
|
594 |
|
|
></TABLE
|
595 |
|
|
><P
|
596 |
|
|
>Other components or options have a calculated value. These
|
597 |
|
|
are not user-modifiable, but typically the value will depend on
|
598 |
|
|
other options which can be modified. Such calculated options can
|
599 |
|
|
be useful when controlling what gets built or what ends up in the
|
600 |
|
|
generated configuration header files. A calculated value may also
|
601 |
|
|
effect other parts of the configuration, for instance, via a <SPAN
|
602 |
|
|
CLASS="emphasis"
|
603 |
|
|
><I
|
604 |
|
|
CLASS="EMPHASIS"
|
605 |
|
|
>requires</I
|
606 |
|
|
></SPAN
|
607 |
|
|
> constraint.</P
|
608 |
|
|
><TABLE
|
609 |
|
|
BORDER="5"
|
610 |
|
|
BGCOLOR="#E0E0F0"
|
611 |
|
|
WIDTH="70%"
|
612 |
|
|
><TR
|
613 |
|
|
><TD
|
614 |
|
|
><PRE
|
615 |
|
|
CLASS="SCREEN"
|
616 |
|
|
> cdl_option BUFSIZ {
|
617 |
|
|
# Calculated value: CYGSEM_LIBC_STDIO_WANT_BUFFERED_IO ? CYGNUM_LIBC_STDIO_BUFSIZE : 0
|
618 |
|
|
# CYGSEM_LIBC_STDIO_WANT_BUFFERED_IO == 1
|
619 |
|
|
# CYGNUM_LIBC_STDIO_BUFSIZE == 256
|
620 |
|
|
# Current_value: 256
|
621 |
|
|
}; </PRE
|
622 |
|
|
></TD
|
623 |
|
|
></TR
|
624 |
|
|
></TABLE
|
625 |
|
|
><P
|
626 |
|
|
>A special type of calculated value is the <SPAN
|
627 |
|
|
CLASS="emphasis"
|
628 |
|
|
><I
|
629 |
|
|
CLASS="EMPHASIS"
|
630 |
|
|
>interface</I
|
631 |
|
|
></SPAN
|
632 |
|
|
>.
|
633 |
|
|
The value of an interface is the number of active and enabled options
|
634 |
|
|
which <SPAN
|
635 |
|
|
CLASS="emphasis"
|
636 |
|
|
><I
|
637 |
|
|
CLASS="EMPHASIS"
|
638 |
|
|
>implement</I
|
639 |
|
|
></SPAN
|
640 |
|
|
> that interface. Again the value
|
641 |
|
|
of an interface cannot be modified directly; only by modifying the
|
642 |
|
|
options which implement the interface. However, an interface can
|
643 |
|
|
be referenced by other parts of the configuration. </P
|
644 |
|
|
><TABLE
|
645 |
|
|
BORDER="5"
|
646 |
|
|
BGCOLOR="#E0E0F0"
|
647 |
|
|
WIDTH="70%"
|
648 |
|
|
><TR
|
649 |
|
|
><TD
|
650 |
|
|
><PRE
|
651 |
|
|
CLASS="SCREEN"
|
652 |
|
|
>cdl_interface CYGINT_KERNEL_SCHEDULER {
|
653 |
|
|
# Implemented by CYGSEM_KERNEL_SCHED_MLQUEUE, active, enabled
|
654 |
|
|
# Implemented by CYGSEM_KERNEL_SCHED_BITMAP, active, disabled
|
655 |
|
|
# This value cannot be modified here.
|
656 |
|
|
# Current_value: 1
|
657 |
|
|
# Requires: 1 == CYGINT_KERNEL_SCHEDULER
|
658 |
|
|
# CYGINT_KERNEL_SCHEDULER == 1
|
659 |
|
|
# --> 1 </PRE
|
660 |
|
|
></TD
|
661 |
|
|
></TR
|
662 |
|
|
></TABLE
|
663 |
|
|
><TABLE
|
664 |
|
|
BORDER="5"
|
665 |
|
|
BGCOLOR="#E0E0F0"
|
666 |
|
|
WIDTH="70%"
|
667 |
|
|
><TR
|
668 |
|
|
><TD
|
669 |
|
|
><PRE
|
670 |
|
|
CLASS="SCREEN"
|
671 |
|
|
># The following properties are affected by this value
|
672 |
|
|
# interface CYGINT_KERNEL_SCHEDULER
|
673 |
|
|
# Requires: 1 == CYGINT_KERNEL_SCHEDULER
|
674 |
|
|
}; </PRE
|
675 |
|
|
></TD
|
676 |
|
|
></TR
|
677 |
|
|
></TABLE
|
678 |
|
|
><P
|
679 |
|
|
>If the configurable entity is modifiable then there will be
|
680 |
|
|
lines like the following:</P
|
681 |
|
|
><TABLE
|
682 |
|
|
BORDER="5"
|
683 |
|
|
BGCOLOR="#E0E0F0"
|
684 |
|
|
WIDTH="70%"
|
685 |
|
|
><TR
|
686 |
|
|
><TD
|
687 |
|
|
><PRE
|
688 |
|
|
CLASS="SCREEN"
|
689 |
|
|
>
|
690 |
|
|
cdl_option CYGSEM_KERNEL_SCHED_MLQUEUE {
|
691 |
|
|
...
|
692 |
|
|
# Flavor: bool
|
693 |
|
|
# No user value, uncomment the following line to provide one.
|
694 |
|
|
# user_value 1
|
695 |
|
|
# value_source default
|
696 |
|
|
# Default value: 1
|
697 |
|
|
...
|
698 |
|
|
}; </PRE
|
699 |
|
|
></TD
|
700 |
|
|
></TR
|
701 |
|
|
></TABLE
|
702 |
|
|
><P
|
703 |
|
|
>Configurable entities can have one of four different flavors:
|
704 |
|
|
none, bool, data and booldata. Flavor none indicates that there
|
705 |
|
|
is no data associated with the entity, typically it just acts as
|
706 |
|
|
a placeholder in the overall hierarchy. Flavor bool is the most
|
707 |
|
|
common, it is a simple yes-or-no choice. Flavor data is for more
|
708 |
|
|
complicated configuration choices, for instance the size of an array
|
709 |
|
|
or the name of a device. Flavor booldata is a combination of bool
|
710 |
|
|
and data: the option can be enabled or disabled, and there is some
|
711 |
|
|
additional data associated with the option as well.</P
|
712 |
|
|
><P
|
713 |
|
|
>In the above example the user has not modified this particular
|
714 |
|
|
option, as indicated by the comment and by the commented-out <TT
|
715 |
|
|
CLASS="LITERAL"
|
716 |
|
|
>user_value</TT
|
717 |
|
|
> line.
|
718 |
|
|
To disable this option the file should be edited to:</P
|
719 |
|
|
><TABLE
|
720 |
|
|
BORDER="5"
|
721 |
|
|
BGCOLOR="#E0E0F0"
|
722 |
|
|
WIDTH="70%"
|
723 |
|
|
><TR
|
724 |
|
|
><TD
|
725 |
|
|
><PRE
|
726 |
|
|
CLASS="SCREEN"
|
727 |
|
|
> cdl_option CYGSEM_KERNEL_SCHED_MLQUEUE {
|
728 |
|
|
...
|
729 |
|
|
# Flavor: bool
|
730 |
|
|
# No user value, uncomment the following line to provide one.
|
731 |
|
|
user_value 0
|
732 |
|
|
# value_source default
|
733 |
|
|
# Default value: 1
|
734 |
|
|
...
|
735 |
|
|
} </PRE
|
736 |
|
|
></TD
|
737 |
|
|
></TR
|
738 |
|
|
></TABLE
|
739 |
|
|
><P
|
740 |
|
|
>The comment preceding the <TT
|
741 |
|
|
CLASS="LITERAL"
|
742 |
|
|
>user_value
|
743 |
|
|
0</TT
|
744 |
|
|
> line can be removed if desired, otherwise it
|
745 |
|
|
will be removed automatically the next time the file is read and
|
746 |
|
|
updated by the configuration tools.</P
|
747 |
|
|
><P
|
748 |
|
|
>Much the same process should be used for options with the
|
749 |
|
|
data flavor, for example:</P
|
750 |
|
|
><TABLE
|
751 |
|
|
BORDER="5"
|
752 |
|
|
BGCOLOR="#E0E0F0"
|
753 |
|
|
WIDTH="70%"
|
754 |
|
|
><TR
|
755 |
|
|
><TD
|
756 |
|
|
><PRE
|
757 |
|
|
CLASS="SCREEN"
|
758 |
|
|
>
|
759 |
|
|
cdl_option CYGNUM_LIBC_TIME_DST_DEFAULT_OFFSET {
|
760 |
|
|
# Flavor: data
|
761 |
|
|
# No user value, uncomment the following line to provide one.
|
762 |
|
|
# user_value 3600
|
763 |
|
|
# value_source default
|
764 |
|
|
# Default value: 3600
|
765 |
|
|
# Legal values: -90000 to 90000
|
766 |
|
|
}; </PRE
|
767 |
|
|
></TD
|
768 |
|
|
></TR
|
769 |
|
|
></TABLE
|
770 |
|
|
><P
|
771 |
|
|
>can be changed to:</P
|
772 |
|
|
><TABLE
|
773 |
|
|
BORDER="5"
|
774 |
|
|
BGCOLOR="#E0E0F0"
|
775 |
|
|
WIDTH="70%"
|
776 |
|
|
><TR
|
777 |
|
|
><TD
|
778 |
|
|
><PRE
|
779 |
|
|
CLASS="SCREEN"
|
780 |
|
|
> cdl_option CYGNUM_LIBC_TIME_DST_DEFAULT_OFFSET {
|
781 |
|
|
# Flavor: data
|
782 |
|
|
user_value 7200
|
783 |
|
|
# value_source default
|
784 |
|
|
# Default value: 3600
|
785 |
|
|
# Legal values: -90000 to 90000 }; </PRE
|
786 |
|
|
></TD
|
787 |
|
|
></TR
|
788 |
|
|
></TABLE
|
789 |
|
|
><P
|
790 |
|
|
>Note that the original text provides the default value in
|
791 |
|
|
the <TT
|
792 |
|
|
CLASS="LITERAL"
|
793 |
|
|
>user_value</TT
|
794 |
|
|
> comment,
|
795 |
|
|
on the assumption that the desired new value is likely to be similar
|
796 |
|
|
to the default value. The <TT
|
797 |
|
|
CLASS="LITERAL"
|
798 |
|
|
>value_source</TT
|
799 |
|
|
> comment
|
800 |
|
|
does not need to be updated, it will be fixed up if the savefile
|
801 |
|
|
is fed back into the configuration system and regenerated.</P
|
802 |
|
|
><P
|
803 |
|
|
>For options with the booldata flavor, the <TT
|
804 |
|
|
CLASS="LITERAL"
|
805 |
|
|
>user_value</TT
|
806 |
|
|
> line
|
807 |
|
|
needs take two arguments. The first argument is for the boolean
|
808 |
|
|
part, the second for the data part. For example:</P
|
809 |
|
|
><TABLE
|
810 |
|
|
BORDER="5"
|
811 |
|
|
BGCOLOR="#E0E0F0"
|
812 |
|
|
WIDTH="70%"
|
813 |
|
|
><TR
|
814 |
|
|
><TD
|
815 |
|
|
><PRE
|
816 |
|
|
CLASS="SCREEN"
|
817 |
|
|
>
|
818 |
|
|
cdl_component CYGNUM_LIBM_COMPATIBILITY {
|
819 |
|
|
# Flavor: booldata
|
820 |
|
|
# No user value, uncomment the following line to provide one.
|
821 |
|
|
# user_value 1 POSIX
|
822 |
|
|
# value_source default
|
823 |
|
|
# Default value: 1 POSIX
|
824 |
|
|
# Legal values: “POSIX” “IEEE” “XOPEN” “SVID”
|
825 |
|
|
...
|
826 |
|
|
}; </PRE
|
827 |
|
|
></TD
|
828 |
|
|
></TR
|
829 |
|
|
></TABLE
|
830 |
|
|
><P
|
831 |
|
|
>could be changed to:</P
|
832 |
|
|
><TABLE
|
833 |
|
|
BORDER="5"
|
834 |
|
|
BGCOLOR="#E0E0F0"
|
835 |
|
|
WIDTH="70%"
|
836 |
|
|
><TR
|
837 |
|
|
><TD
|
838 |
|
|
><PRE
|
839 |
|
|
CLASS="SCREEN"
|
840 |
|
|
>
|
841 |
|
|
cdl_component CYGNUM_LIBM_COMPATIBILITY {
|
842 |
|
|
# Flavor: booldata
|
843 |
|
|
user_value 1 IEEE
|
844 |
|
|
# value_source default
|
845 |
|
|
# Default value: 1 POSIX
|
846 |
|
|
# Legal values: “POSIX” “IEEE” “XOPEN” “SVID”
|
847 |
|
|
...
|
848 |
|
|
}; </PRE
|
849 |
|
|
></TD
|
850 |
|
|
></TR
|
851 |
|
|
></TABLE
|
852 |
|
|
><P
|
853 |
|
|
>or alternatively, if the whole component should be disabled,
|
854 |
|
|
to:</P
|
855 |
|
|
><TABLE
|
856 |
|
|
BORDER="5"
|
857 |
|
|
BGCOLOR="#E0E0F0"
|
858 |
|
|
WIDTH="70%"
|
859 |
|
|
><TR
|
860 |
|
|
><TD
|
861 |
|
|
><PRE
|
862 |
|
|
CLASS="SCREEN"
|
863 |
|
|
>
|
864 |
|
|
cdl_component CYGNUM_LIBM_COMPATIBILITY {
|
865 |
|
|
# Flavor: booldata
|
866 |
|
|
user_value 0 POSIX
|
867 |
|
|
# value_source default
|
868 |
|
|
# Default value: 1 POSIX
|
869 |
|
|
# Legal values: “POSIX” “IEEE” “XOPEN” “SVID”
|
870 |
|
|
...
|
871 |
|
|
}; </PRE
|
872 |
|
|
></TD
|
873 |
|
|
></TR
|
874 |
|
|
></TABLE
|
875 |
|
|
><P
|
876 |
|
|
>Some options take values that span multiple lines. An example
|
877 |
|
|
would be:</P
|
878 |
|
|
><TABLE
|
879 |
|
|
BORDER="5"
|
880 |
|
|
BGCOLOR="#E0E0F0"
|
881 |
|
|
WIDTH="70%"
|
882 |
|
|
><TR
|
883 |
|
|
><TD
|
884 |
|
|
><PRE
|
885 |
|
|
CLASS="SCREEN"
|
886 |
|
|
> cdl_option CYGDAT_UITRON_MEMPOOLVAR_INITIALIZERS {
|
887 |
|
|
# Flavor: data
|
888 |
|
|
# No user value, uncomment the following line to provide one.
|
889 |
|
|
# user_value \
|
890 |
|
|
# “CYG_UIT_MEMPOOLVAR( vpool1, 2000 ), \\
|
891 |
|
|
# CYG_UIT_MEMPOOLVAR( vpool2, 2000 ), \\
|
892 |
|
|
# CYG_UIT_MEMPOOLVAR( vpool3, 2000 ),”
|
893 |
|
|
# value_source default
|
894 |
|
|
# Default value: \
|
895 |
|
|
# “CYG_UIT_MEMPOOLVAR( vpool1, 2000 ), \\
|
896 |
|
|
# CYG_UIT_MEMPOOLVAR( vpool2, 2000 ), \\
|
897 |
|
|
# CYG_UIT_MEMPOOLVAR( vpool3, 2000 ),”
|
898 |
|
|
}; </PRE
|
899 |
|
|
></TD
|
900 |
|
|
></TR
|
901 |
|
|
></TABLE
|
902 |
|
|
><P
|
903 |
|
|
>Setting a user value for this option involves uncommenting
|
904 |
|
|
and modifying all relevant lines, for example:</P
|
905 |
|
|
><TABLE
|
906 |
|
|
BORDER="5"
|
907 |
|
|
BGCOLOR="#E0E0F0"
|
908 |
|
|
WIDTH="70%"
|
909 |
|
|
><TR
|
910 |
|
|
><TD
|
911 |
|
|
><PRE
|
912 |
|
|
CLASS="SCREEN"
|
913 |
|
|
> cdl_option CYGDAT_UITRON_MEMPOOLVAR_INITIALIZERS {
|
914 |
|
|
# Flavor: data
|
915 |
|
|
user_value \
|
916 |
|
|
“CYG_UIT_MEMPOOLVAR( vpool1, 4000 ), \\
|
917 |
|
|
CYG_UIT_MEMPOOLVAR( vpool2, 4000 ),”
|
918 |
|
|
# value_source default
|
919 |
|
|
# Default value: \
|
920 |
|
|
# “CYG_UIT_MEMPOOLVAR( vpool1, 2000 ), \\
|
921 |
|
|
# CYG_UIT_MEMPOOLVAR( vpool2, 2000 ), \\
|
922 |
|
|
# CYG_UIT_MEMPOOLVAR( vpool3, 2000 ),”
|
923 |
|
|
}; </PRE
|
924 |
|
|
></TD
|
925 |
|
|
></TR
|
926 |
|
|
></TABLE
|
927 |
|
|
><P
|
928 |
|
|
>In such cases appropriate care has to be taken to preserve
|
929 |
|
|
Tcl syntax, as discussed below.</P
|
930 |
|
|
><P
|
931 |
|
|
>The configuration system has the ability to keep track of
|
932 |
|
|
several different values for any given option. All options
|
933 |
|
|
start off with a default value, in other words their value
|
934 |
|
|
source is set to <TT
|
935 |
|
|
CLASS="LITERAL"
|
936 |
|
|
>default</TT
|
937 |
|
|
>. If a
|
938 |
|
|
configuration involves conflicts and the configuration
|
939 |
|
|
system’s inference engine is allowed to resolve these
|
940 |
|
|
automatically then it may provide an
|
941 |
|
|
<TT
|
942 |
|
|
CLASS="LITERAL"
|
943 |
|
|
>inferred</TT
|
944 |
|
|
> value instead, for
|
945 |
|
|
example:</P
|
946 |
|
|
><TABLE
|
947 |
|
|
BORDER="5"
|
948 |
|
|
BGCOLOR="#E0E0F0"
|
949 |
|
|
WIDTH="70%"
|
950 |
|
|
><TR
|
951 |
|
|
><TD
|
952 |
|
|
><PRE
|
953 |
|
|
CLASS="SCREEN"
|
954 |
|
|
> cdl_option CYGMFN_KERNEL_SYNCH_CONDVAR_TIMED_WAIT {
|
955 |
|
|
# Flavor: bool
|
956 |
|
|
# No user value, uncomment the following line to provide one.
|
957 |
|
|
# user_value 1
|
958 |
|
|
# The inferred value should not be edited directly.
|
959 |
|
|
inferred_value 0
|
960 |
|
|
# value_source inferred
|
961 |
|
|
# Default value: 1
|
962 |
|
|
...
|
963 |
|
|
}; </PRE
|
964 |
|
|
></TD
|
965 |
|
|
></TR
|
966 |
|
|
></TABLE
|
967 |
|
|
><P
|
968 |
|
|
>Inferred values are calculated by the configuration system
|
969 |
|
|
and should not be edited by the user. If the inferred value is not
|
970 |
|
|
correct then a user value should be substituted instead:</P
|
971 |
|
|
><TABLE
|
972 |
|
|
BORDER="5"
|
973 |
|
|
BGCOLOR="#E0E0F0"
|
974 |
|
|
WIDTH="70%"
|
975 |
|
|
><TR
|
976 |
|
|
><TD
|
977 |
|
|
><PRE
|
978 |
|
|
CLASS="SCREEN"
|
979 |
|
|
> cdl_option CYGMFN_KERNEL_SYNCH_CONDVAR_TIMED_WAIT {
|
980 |
|
|
# Flavor: bool
|
981 |
|
|
user_value 1
|
982 |
|
|
# The inferred value should not be edited directly.
|
983 |
|
|
inferred_value 0
|
984 |
|
|
# value_source inferred
|
985 |
|
|
# Default value: 1
|
986 |
|
|
...
|
987 |
|
|
}; </PRE
|
988 |
|
|
></TD
|
989 |
|
|
></TR
|
990 |
|
|
></TABLE
|
991 |
|
|
><P
|
992 |
|
|
>The inference engine will not override a user value with an
|
993 |
|
|
inferred one. Making a change like this may well re-introduce a
|
994 |
|
|
conflict, since the inferred value was only calculated to resolve
|
995 |
|
|
a conflict. Another run of the inference engine may find a different
|
996 |
|
|
and more acceptable way of resolving the conflict, but this is not guaranteed
|
997 |
|
|
and it may be up to the user to examine the various dependencies
|
998 |
|
|
and work out an acceptable solution.</P
|
999 |
|
|
><P
|
1000 |
|
|
>Inferred values are listed in the savefile because the exact
|
1001 |
|
|
inferred value may depend on the order in which changes were made
|
1002 |
|
|
and conflicts were resolved. If the inferred values were absent
|
1003 |
|
|
then it is possible that reloading a savefile would not exactly
|
1004 |
|
|
restore the configuration. Default values on the other hand are
|
1005 |
|
|
entirely deterministic so there is no actual need for the values
|
1006 |
|
|
to be listed in the savefile. However, the default value can be
|
1007 |
|
|
very useful information so it is provided in a comment.</P
|
1008 |
|
|
><P
|
1009 |
|
|
>Occasionally the user will want to do some experimentation,
|
1010 |
|
|
and temporarily switch an option from a user value back to a default
|
1011 |
|
|
or inferred one to see what the effect would be. This could be achieved
|
1012 |
|
|
by simply commenting out the user value. For instance, if the current
|
1013 |
|
|
savefile contains:</P
|
1014 |
|
|
><TABLE
|
1015 |
|
|
BORDER="5"
|
1016 |
|
|
BGCOLOR="#E0E0F0"
|
1017 |
|
|
WIDTH="70%"
|
1018 |
|
|
><TR
|
1019 |
|
|
><TD
|
1020 |
|
|
><PRE
|
1021 |
|
|
CLASS="SCREEN"
|
1022 |
|
|
>
|
1023 |
|
|
cdl_option CYGMFN_KERNEL_SYNCH_CONDVAR_TIMED_WAIT {
|
1024 |
|
|
# Flavor: bool
|
1025 |
|
|
user_value 1
|
1026 |
|
|
# The inferred value should not be edited directly.
|
1027 |
|
|
inferred_value 0
|
1028 |
|
|
# value_source user
|
1029 |
|
|
# Default value: 1
|
1030 |
|
|
...
|
1031 |
|
|
}; </PRE
|
1032 |
|
|
></TD
|
1033 |
|
|
></TR
|
1034 |
|
|
></TABLE
|
1035 |
|
|
><P
|
1036 |
|
|
>then the inferred value could be restored by commenting out
|
1037 |
|
|
or removing the <TT
|
1038 |
|
|
CLASS="LITERAL"
|
1039 |
|
|
>user_value</TT
|
1040 |
|
|
> line:</P
|
1041 |
|
|
><TABLE
|
1042 |
|
|
BORDER="5"
|
1043 |
|
|
BGCOLOR="#E0E0F0"
|
1044 |
|
|
WIDTH="70%"
|
1045 |
|
|
><TR
|
1046 |
|
|
><TD
|
1047 |
|
|
><PRE
|
1048 |
|
|
CLASS="SCREEN"
|
1049 |
|
|
>
|
1050 |
|
|
cdl_option CYGMFN_KERNEL_SYNCH_CONDVAR_TIMED_WAIT {
|
1051 |
|
|
# Flavor: bool
|
1052 |
|
|
# user_value 1
|
1053 |
|
|
# The inferred value should not be edited directly.
|
1054 |
|
|
inferred_value 0
|
1055 |
|
|
# value_source user
|
1056 |
|
|
# Default value: 1
|
1057 |
|
|
...
|
1058 |
|
|
}; </PRE
|
1059 |
|
|
></TD
|
1060 |
|
|
></TR
|
1061 |
|
|
></TABLE
|
1062 |
|
|
><P
|
1063 |
|
|
>This is fine for simple values. However if the value is complicated
|
1064 |
|
|
then there is a problem: commenting out the <TT
|
1065 |
|
|
CLASS="LITERAL"
|
1066 |
|
|
>user_value</TT
|
1067 |
|
|
> line
|
1068 |
|
|
or lines means that the user value becomes invisible to the configuration system,
|
1069 |
|
|
so if the savefile is loaded and then regenerated the information
|
1070 |
|
|
will be lost. An alternative approach is to keep the <TT
|
1071 |
|
|
CLASS="LITERAL"
|
1072 |
|
|
>user_value</TT
|
1073 |
|
|
> but
|
1074 |
|
|
explicitly set the <TT
|
1075 |
|
|
CLASS="LITERAL"
|
1076 |
|
|
>value_source</TT
|
1077 |
|
|
> line,
|
1078 |
|
|
for example:</P
|
1079 |
|
|
><TABLE
|
1080 |
|
|
BORDER="5"
|
1081 |
|
|
BGCOLOR="#E0E0F0"
|
1082 |
|
|
WIDTH="70%"
|
1083 |
|
|
><TR
|
1084 |
|
|
><TD
|
1085 |
|
|
><PRE
|
1086 |
|
|
CLASS="SCREEN"
|
1087 |
|
|
> cdl_option CYGMFN_KERNEL_SYNCH_CONDVAR_TIMED_WAIT {
|
1088 |
|
|
# Flavor: bool
|
1089 |
|
|
user_value 1
|
1090 |
|
|
# The inferred value should not be edited directly.
|
1091 |
|
|
inferred_value 0
|
1092 |
|
|
value_source inferred
|
1093 |
|
|
# Default value: 1
|
1094 |
|
|
...
|
1095 |
|
|
}; </PRE
|
1096 |
|
|
></TD
|
1097 |
|
|
></TR
|
1098 |
|
|
></TABLE
|
1099 |
|
|
><P
|
1100 |
|
|
>In this case the configuration system will use the inferred
|
1101 |
|
|
value for the purposes of dependency analysis etc., even though
|
1102 |
|
|
a user value is present. To restore the user value the <TT
|
1103 |
|
|
CLASS="LITERAL"
|
1104 |
|
|
>value_source</TT
|
1105 |
|
|
> line
|
1106 |
|
|
can be commented out again. If there is no explicit <TT
|
1107 |
|
|
CLASS="LITERAL"
|
1108 |
|
|
>value_source</TT
|
1109 |
|
|
> then
|
1110 |
|
|
the configuration system will just use the highest priority one:
|
1111 |
|
|
the user value if it exists; otherwise the inferred value if it
|
1112 |
|
|
exists; otherwise the default value which always exists.</P
|
1113 |
|
|
><P
|
1114 |
|
|
>The default value for an option can be a simple constant,
|
1115 |
|
|
or it can be an expression involving other options. In the latter
|
1116 |
|
|
case the expression will be listed, together with the values for
|
1117 |
|
|
all options referenced in the expression and the current result
|
1118 |
|
|
of evaluating that expression. This is for informational purposes
|
1119 |
|
|
only, the default value is always recalculated deterministically
|
1120 |
|
|
when loading in a savefile.</P
|
1121 |
|
|
><TABLE
|
1122 |
|
|
BORDER="5"
|
1123 |
|
|
BGCOLOR="#E0E0F0"
|
1124 |
|
|
WIDTH="70%"
|
1125 |
|
|
><TR
|
1126 |
|
|
><TD
|
1127 |
|
|
><PRE
|
1128 |
|
|
CLASS="SCREEN"
|
1129 |
|
|
> cdl_option CYGBLD_GLOBAL_COMMAND_PREFIX {
|
1130 |
|
|
# Flavor: data
|
1131 |
|
|
# No user value, uncomment the following line to provide one.
|
1132 |
|
|
# user_value arm-elf
|
1133 |
|
|
# value_source default
|
1134 |
|
|
# Default value: CYGHWR_THUMB ? “thumb-elf” : “arm-elf”
|
1135 |
|
|
# CYGHWR_THUMB == 0
|
1136 |
|
|
# --> arm-elf
|
1137 |
|
|
}; </PRE
|
1138 |
|
|
></TD
|
1139 |
|
|
></TR
|
1140 |
|
|
></TABLE
|
1141 |
|
|
><P
|
1142 |
|
|
>For options with the data or booldata flavor, there are likely
|
1143 |
|
|
to be constraints on the possible values. If the value is supposed
|
1144 |
|
|
to be a number in a given range and a user value of “<TT
|
1145 |
|
|
CLASS="LITERAL"
|
1146 |
|
|
>hello
|
1147 |
|
|
world</TT
|
1148 |
|
|
>” is provided instead then there
|
1149 |
|
|
are likely to be compile-time failures. Component developers can
|
1150 |
|
|
specify constraints on the legal values, and these will be listed
|
1151 |
|
|
in the savefile.</P
|
1152 |
|
|
><TABLE
|
1153 |
|
|
BORDER="5"
|
1154 |
|
|
BGCOLOR="#E0E0F0"
|
1155 |
|
|
WIDTH="70%"
|
1156 |
|
|
><TR
|
1157 |
|
|
><TD
|
1158 |
|
|
><PRE
|
1159 |
|
|
CLASS="SCREEN"
|
1160 |
|
|
>
|
1161 |
|
|
cdl_option X_TLOSS {
|
1162 |
|
|
# Flavor: data
|
1163 |
|
|
# No user value, uncomment the following line to provide one.
|
1164 |
|
|
# user_value 1.41484755040569E+16
|
1165 |
|
|
# value_source default
|
1166 |
|
|
# Default value: 1.41484755040569E+16
|
1167 |
|
|
# Legal values: 1 to 1e308
|
1168 |
|
|
}; </PRE
|
1169 |
|
|
></TD
|
1170 |
|
|
></TR
|
1171 |
|
|
></TABLE
|
1172 |
|
|
><TABLE
|
1173 |
|
|
BORDER="5"
|
1174 |
|
|
BGCOLOR="#E0E0F0"
|
1175 |
|
|
WIDTH="70%"
|
1176 |
|
|
><TR
|
1177 |
|
|
><TD
|
1178 |
|
|
><PRE
|
1179 |
|
|
CLASS="SCREEN"
|
1180 |
|
|
>cdl_component CYGNUM_LIBM_COMPATIBILITY {
|
1181 |
|
|
# Flavor: booldata
|
1182 |
|
|
# No user value, uncomment the following line to provide one.
|
1183 |
|
|
# user_value 1 POSIX
|
1184 |
|
|
# value_source default
|
1185 |
|
|
# Default value: 1 POSIX
|
1186 |
|
|
# Legal values: “POSIX” “IEEE” “XOPEN” “SVID”
|
1187 |
|
|
...
|
1188 |
|
|
}; </PRE
|
1189 |
|
|
></TD
|
1190 |
|
|
></TR
|
1191 |
|
|
></TABLE
|
1192 |
|
|
><P
|
1193 |
|
|
>In some cases the legal values list may be an expression involving
|
1194 |
|
|
other options. If so then the current values of the referenced options
|
1195 |
|
|
will be listed, together with the result of evaluating the list
|
1196 |
|
|
expression, just as for default value expressions.</P
|
1197 |
|
|
><P
|
1198 |
|
|
>If an illegal value is provided then this will result in a
|
1199 |
|
|
conflict, listed in the conflicts section of the savefile. For more
|
1200 |
|
|
complicated options a simple legal values list is not sufficient
|
1201 |
|
|
to allow the current value to be validated, and the configuration
|
1202 |
|
|
system will be unable to flag conflicts. This issue will be addressed in
|
1203 |
|
|
future releases of the configuration system.</P
|
1204 |
|
|
><P
|
1205 |
|
|
>Following the value-related fields for a given option, any <SPAN
|
1206 |
|
|
CLASS="emphasis"
|
1207 |
|
|
><I
|
1208 |
|
|
CLASS="EMPHASIS"
|
1209 |
|
|
>requires</I
|
1210 |
|
|
></SPAN
|
1211 |
|
|
> constraints belonging
|
1212 |
|
|
to this option will be listed. These constraints are only effective
|
1213 |
|
|
if the option is active and, for bool and booldata flavors, enabled.
|
1214 |
|
|
If some aspect of <SPAN
|
1215 |
|
|
CLASS="PRODUCTNAME"
|
1216 |
|
|
>eCos</SPAN
|
1217 |
|
|
> functionality is inactive or disabled then
|
1218 |
|
|
it cannot impose any constraints on the rest of the system. As usual,
|
1219 |
|
|
the full expression will be listed followed by the current values
|
1220 |
|
|
of all options that are referenced and the result of evaluating
|
1221 |
|
|
the expression:</P
|
1222 |
|
|
><TABLE
|
1223 |
|
|
BORDER="5"
|
1224 |
|
|
BGCOLOR="#E0E0F0"
|
1225 |
|
|
WIDTH="70%"
|
1226 |
|
|
><TR
|
1227 |
|
|
><TD
|
1228 |
|
|
><PRE
|
1229 |
|
|
CLASS="SCREEN"
|
1230 |
|
|
> cdl_option CYGSEM_LIBC_TIME_TIME_WORKING {
|
1231 |
|
|
...
|
1232 |
|
|
# Requires: CYGPKG_DEVICES_WALLCLOCK
|
1233 |
|
|
# CYGPKG_DEVICES_WALLCLOCK == current
|
1234 |
|
|
# --> 1
|
1235 |
|
|
}; </PRE
|
1236 |
|
|
></TD
|
1237 |
|
|
></TR
|
1238 |
|
|
></TABLE
|
1239 |
|
|
><P
|
1240 |
|
|
>When modifying the value of an option it is useful to know
|
1241 |
|
|
not only what constraints the option imposes on the rest of the
|
1242 |
|
|
system but also what other options in the system depend in some
|
1243 |
|
|
way on this one. The savefile provides this information:</P
|
1244 |
|
|
><TABLE
|
1245 |
|
|
BORDER="5"
|
1246 |
|
|
BGCOLOR="#E0E0F0"
|
1247 |
|
|
WIDTH="70%"
|
1248 |
|
|
><TR
|
1249 |
|
|
><TD
|
1250 |
|
|
><PRE
|
1251 |
|
|
CLASS="SCREEN"
|
1252 |
|
|
>cdl_option CYGFUN_KERNEL_THREADS_TIMER {
|
1253 |
|
|
...
|
1254 |
|
|
# The following properties are affected by this value
|
1255 |
|
|
# option CYGMFN_KERNEL_SYNCH_CONDVAR_TIMED_WAIT
|
1256 |
|
|
# Requires: CYGFUN_KERNEL_THREADS_TIMER
|
1257 |
|
|
# option CYGIMP_UITRON_STRICT_CONFORMANCE
|
1258 |
|
|
# Requires: CYGFUN_KERNEL_THREADS_TIMER
|
1259 |
|
|
# option CYGSEM_LIBC_TIME_CLOCK_WORKING
|
1260 |
|
|
# Requires: CYGFUN_KERNEL_THREADS_TIMER
|
1261 |
|
|
}; </PRE
|
1262 |
|
|
></TD
|
1263 |
|
|
></TR
|
1264 |
|
|
></TABLE
|
1265 |
|
|
></DIV
|
1266 |
|
|
><DIV
|
1267 |
|
|
CLASS="SECT2"
|
1268 |
|
|
><H2
|
1269 |
|
|
CLASS="SECT2"
|
1270 |
|
|
><A
|
1271 |
|
|
NAME="AEN2847">Tcl Syntax</H2
|
1272 |
|
|
><P
|
1273 |
|
|
><SPAN
|
1274 |
|
|
CLASS="PRODUCTNAME"
|
1275 |
|
|
>eCos</SPAN
|
1276 |
|
|
> savefiles are implemented as Tcl scripts, and are read
|
1277 |
|
|
in by running the data through a standard Tcl interpreter that has
|
1278 |
|
|
been extended with a small number of additional commands such as <TT
|
1279 |
|
|
CLASS="LITERAL"
|
1280 |
|
|
>cdl_option</TT
|
1281 |
|
|
> and <TT
|
1282 |
|
|
CLASS="LITERAL"
|
1283 |
|
|
>cdl_configuration</TT
|
1284 |
|
|
>.
|
1285 |
|
|
In many cases this is an implementation detail that can be safely
|
1286 |
|
|
ignored while editing a savefile: simply replacing a <TT
|
1287 |
|
|
CLASS="LITERAL"
|
1288 |
|
|
>1</TT
|
1289 |
|
|
> with
|
1290 |
|
|
a <TT
|
1291 |
|
|
CLASS="LITERAL"
|
1292 |
|
|
>0</TT
|
1293 |
|
|
> to disable some functionality
|
1294 |
|
|
is not going to affect whether or not the savefile is still a valid
|
1295 |
|
|
Tcl script and can be processed by a Tcl interpreter. However, there
|
1296 |
|
|
are more complicated cases where an understanding of Tcl syntax
|
1297 |
|
|
is at least desirable, for example:</P
|
1298 |
|
|
><TABLE
|
1299 |
|
|
BORDER="5"
|
1300 |
|
|
BGCOLOR="#E0E0F0"
|
1301 |
|
|
WIDTH="70%"
|
1302 |
|
|
><TR
|
1303 |
|
|
><TD
|
1304 |
|
|
><PRE
|
1305 |
|
|
CLASS="SCREEN"
|
1306 |
|
|
> cdl_option CYGDAT_UITRON_MEMPOOLVAR_EXTERNS {
|
1307 |
|
|
# Flavor: data
|
1308 |
|
|
user_value \
|
1309 |
|
|
“static char vpool1\[ 2000 \], \\
|
1310 |
|
|
vpool2\[ 2000 \], \\
|
1311 |
|
|
vpool3\[ 2000 \];”
|
1312 |
|
|
# value_source default
|
1313 |
|
|
# Default value: \
|
1314 |
|
|
# “static char vpool1\[ 2000 \], \\
|
1315 |
|
|
# vpool2\[ 2000 \], \\
|
1316 |
|
|
# vpool3\[ 2000 \];”
|
1317 |
|
|
}; </PRE
|
1318 |
|
|
></TD
|
1319 |
|
|
></TR
|
1320 |
|
|
></TABLE
|
1321 |
|
|
><P
|
1322 |
|
|
>The backslash at the end of the <TT
|
1323 |
|
|
CLASS="LITERAL"
|
1324 |
|
|
>user_value</TT
|
1325 |
|
|
> line
|
1326 |
|
|
is processed by the Tcl interpreter as a line continuation character.
|
1327 |
|
|
The quote marks around the user data are also interpreted by the
|
1328 |
|
|
Tcl interpreter and serve to turn the entire data field into a single
|
1329 |
|
|
argument. The backslashes preceding the opening and closing square
|
1330 |
|
|
brackets prevent the Tcl interpreter from treating these characters
|
1331 |
|
|
specially, otherwise there would be an attempt at <SPAN
|
1332 |
|
|
CLASS="emphasis"
|
1333 |
|
|
><I
|
1334 |
|
|
CLASS="EMPHASIS"
|
1335 |
|
|
>command
|
1336 |
|
|
substitution</I
|
1337 |
|
|
></SPAN
|
1338 |
|
|
> as described below. The double backslashes
|
1339 |
|
|
at the end of each line of the data will be turned into a single
|
1340 |
|
|
backslash by the Tcl interpreter, rather than escaping the newline
|
1341 |
|
|
character, so that the actual data seen by the configuration system
|
1342 |
|
|
is:</P
|
1343 |
|
|
><TABLE
|
1344 |
|
|
BORDER="5"
|
1345 |
|
|
BGCOLOR="#E0E0F0"
|
1346 |
|
|
WIDTH="70%"
|
1347 |
|
|
><TR
|
1348 |
|
|
><TD
|
1349 |
|
|
><PRE
|
1350 |
|
|
CLASS="SCREEN"
|
1351 |
|
|
> static char vpool1[ 2000 ], \
|
1352 |
|
|
vpool2[ 2000 ], \
|
1353 |
|
|
vpool3[ 2000 ]; </PRE
|
1354 |
|
|
></TD
|
1355 |
|
|
></TR
|
1356 |
|
|
></TABLE
|
1357 |
|
|
><P
|
1358 |
|
|
>This is of course the data that should end up in the µITRON
|
1359 |
|
|
configuration header file. The opening and closing braces surrounding
|
1360 |
|
|
the entire body of the option data are also significant and cause
|
1361 |
|
|
this body to be passed as a single argument to the <B
|
1362 |
|
|
CLASS="COMMAND"
|
1363 |
|
|
>cdl_option</B
|
1364 |
|
|
> command.
|
1365 |
|
|
The closing semicolon is optional in this example, but provides
|
1366 |
|
|
a small amount of additional robustness if the savefile is edited
|
1367 |
|
|
such that it is no longer a valid Tcl script. If the data contained
|
1368 |
|
|
any <TT
|
1369 |
|
|
CLASS="LITERAL"
|
1370 |
|
|
>$</TT
|
1371 |
|
|
> characters then
|
1372 |
|
|
these would have to be treated specially as well, via a backslash escape.</P
|
1373 |
|
|
><P
|
1374 |
|
|
>In spite of what all the above might seem to suggest, Tcl
|
1375 |
|
|
is actually a very simple yet powerful scripting language: the syntax
|
1376 |
|
|
is defined by just eleven rules. On occasion this simplicity means
|
1377 |
|
|
that Tcl’s behaviour is subtly different from other languages,
|
1378 |
|
|
which can confuse newcomers.</P
|
1379 |
|
|
><P
|
1380 |
|
|
>When the Tcl interpreter is passed some data such as <TT
|
1381 |
|
|
CLASS="LITERAL"
|
1382 |
|
|
>puts
|
1383 |
|
|
Hello</TT
|
1384 |
|
|
>, it splits this data into a command and its
|
1385 |
|
|
arguments. The command will be terminated by a newline or by a semicolon,
|
1386 |
|
|
unless one of the quoting mechanisms is used. The command and each
|
1387 |
|
|
of its arguments are separated by white space. So in the following
|
1388 |
|
|
example:</P
|
1389 |
|
|
><TABLE
|
1390 |
|
|
BORDER="5"
|
1391 |
|
|
BGCOLOR="#E0E0F0"
|
1392 |
|
|
WIDTH="70%"
|
1393 |
|
|
><TR
|
1394 |
|
|
><TD
|
1395 |
|
|
><PRE
|
1396 |
|
|
CLASS="SCREEN"
|
1397 |
|
|
>puts Hello
|
1398 |
|
|
set x 42 </PRE
|
1399 |
|
|
></TD
|
1400 |
|
|
></TR
|
1401 |
|
|
></TABLE
|
1402 |
|
|
><P
|
1403 |
|
|
>will result in two separate commands being executed. The first
|
1404 |
|
|
command is <TT
|
1405 |
|
|
CLASS="LITERAL"
|
1406 |
|
|
>puts</TT
|
1407 |
|
|
> and is passed a
|
1408 |
|
|
single argument, <TT
|
1409 |
|
|
CLASS="LITERAL"
|
1410 |
|
|
>Hello</TT
|
1411 |
|
|
>. The second
|
1412 |
|
|
command is <TT
|
1413 |
|
|
CLASS="LITERAL"
|
1414 |
|
|
>set</TT
|
1415 |
|
|
> and is passed two
|
1416 |
|
|
arguments, <TT
|
1417 |
|
|
CLASS="LITERAL"
|
1418 |
|
|
>x</TT
|
1419 |
|
|
> and <TT
|
1420 |
|
|
CLASS="LITERAL"
|
1421 |
|
|
>42</TT
|
1422 |
|
|
>.
|
1423 |
|
|
The intervening newline character serves to terminate the first
|
1424 |
|
|
command, and a semi-colon separator could be used instead: </P
|
1425 |
|
|
><TABLE
|
1426 |
|
|
BORDER="5"
|
1427 |
|
|
BGCOLOR="#E0E0F0"
|
1428 |
|
|
WIDTH="70%"
|
1429 |
|
|
><TR
|
1430 |
|
|
><TD
|
1431 |
|
|
><PRE
|
1432 |
|
|
CLASS="PROGRAMLISTING"
|
1433 |
|
|
>puts Hello;set x 42</PRE
|
1434 |
|
|
></TD
|
1435 |
|
|
></TR
|
1436 |
|
|
></TABLE
|
1437 |
|
|
><P
|
1438 |
|
|
>Any white space surrounding the semicolon is just ignored
|
1439 |
|
|
because it does not serve to separate arguments.</P
|
1440 |
|
|
><P
|
1441 |
|
|
>Now consider the following:</P
|
1442 |
|
|
><TABLE
|
1443 |
|
|
BORDER="5"
|
1444 |
|
|
BGCOLOR="#E0E0F0"
|
1445 |
|
|
WIDTH="70%"
|
1446 |
|
|
><TR
|
1447 |
|
|
><TD
|
1448 |
|
|
><PRE
|
1449 |
|
|
CLASS="SCREEN"
|
1450 |
|
|
>set x Hello world</PRE
|
1451 |
|
|
></TD
|
1452 |
|
|
></TR
|
1453 |
|
|
></TABLE
|
1454 |
|
|
><P
|
1455 |
|
|
>This is not valid Tcl. It is an attempt to invoke the <TT
|
1456 |
|
|
CLASS="LITERAL"
|
1457 |
|
|
>set</TT
|
1458 |
|
|
> command
|
1459 |
|
|
with three arguments: <TT
|
1460 |
|
|
CLASS="LITERAL"
|
1461 |
|
|
>x</TT
|
1462 |
|
|
>, <TT
|
1463 |
|
|
CLASS="LITERAL"
|
1464 |
|
|
>Hello</TT
|
1465 |
|
|
>,
|
1466 |
|
|
and <TT
|
1467 |
|
|
CLASS="LITERAL"
|
1468 |
|
|
>world</TT
|
1469 |
|
|
>. The <TT
|
1470 |
|
|
CLASS="LITERAL"
|
1471 |
|
|
>set</TT
|
1472 |
|
|
> only
|
1473 |
|
|
takes two arguments, a variable name and a value, so it is necessary
|
1474 |
|
|
to combine the data into a single argument by quoting:</P
|
1475 |
|
|
><TABLE
|
1476 |
|
|
BORDER="5"
|
1477 |
|
|
BGCOLOR="#E0E0F0"
|
1478 |
|
|
WIDTH="70%"
|
1479 |
|
|
><TR
|
1480 |
|
|
><TD
|
1481 |
|
|
><PRE
|
1482 |
|
|
CLASS="PROGRAMLISTING"
|
1483 |
|
|
>set x “Hello world”</PRE
|
1484 |
|
|
></TD
|
1485 |
|
|
></TR
|
1486 |
|
|
></TABLE
|
1487 |
|
|
><P
|
1488 |
|
|
>When the Tcl interpreter encounters the first quote character
|
1489 |
|
|
it treats all subsequent data up to but not including the closing
|
1490 |
|
|
quote as part of the current argument. The quote marks are removed
|
1491 |
|
|
by the interpreter, so the second argument passed to the <TT
|
1492 |
|
|
CLASS="LITERAL"
|
1493 |
|
|
>set</TT
|
1494 |
|
|
> command
|
1495 |
|
|
is just <TT
|
1496 |
|
|
CLASS="LITERAL"
|
1497 |
|
|
>Hello world</TT
|
1498 |
|
|
> without the
|
1499 |
|
|
quote characters. This can be significant in the context of <SPAN
|
1500 |
|
|
CLASS="PRODUCTNAME"
|
1501 |
|
|
>eCos</SPAN
|
1502 |
|
|
> savefiles.
|
1503 |
|
|
For instance, consider the following configuration option:</P
|
1504 |
|
|
><TABLE
|
1505 |
|
|
BORDER="5"
|
1506 |
|
|
BGCOLOR="#E0E0F0"
|
1507 |
|
|
WIDTH="70%"
|
1508 |
|
|
><TR
|
1509 |
|
|
><TD
|
1510 |
|
|
><PRE
|
1511 |
|
|
CLASS="SCREEN"
|
1512 |
|
|
> cdl_option CYGDAT_LIBC_STDIO_DEFAULT_CONSOLE {
|
1513 |
|
|
# Flavor: data
|
1514 |
|
|
# No user value, uncomment the following line to provide one.
|
1515 |
|
|
# user_value “\”/dev/ttydiag\””
|
1516 |
|
|
# value_source default
|
1517 |
|
|
# Default value: “\”/dev/ttydiag\””
|
1518 |
|
|
}; </PRE
|
1519 |
|
|
></TD
|
1520 |
|
|
></TR
|
1521 |
|
|
></TABLE
|
1522 |
|
|
><P
|
1523 |
|
|
>The desired value of the configuration option should be a
|
1524 |
|
|
valid C string, complete with quote characters. If the savefile
|
1525 |
|
|
was edited to: </P
|
1526 |
|
|
><TABLE
|
1527 |
|
|
BORDER="5"
|
1528 |
|
|
BGCOLOR="#E0E0F0"
|
1529 |
|
|
WIDTH="70%"
|
1530 |
|
|
><TR
|
1531 |
|
|
><TD
|
1532 |
|
|
><PRE
|
1533 |
|
|
CLASS="SCREEN"
|
1534 |
|
|
> cdl_option CYGDAT_LIBC_STDIO_DEFAULT_CONSOLE {
|
1535 |
|
|
# Flavor: data
|
1536 |
|
|
user_value “/dev/ttydiag”
|
1537 |
|
|
# value_source default
|
1538 |
|
|
# Default value: “\”/dev/ttydiag\””
|
1539 |
|
|
}; </PRE
|
1540 |
|
|
></TD
|
1541 |
|
|
></TR
|
1542 |
|
|
></TABLE
|
1543 |
|
|
><P
|
1544 |
|
|
>then the Tcl interpreter would remove the quote marks when
|
1545 |
|
|
the savefile is read back in, so the option’s value would
|
1546 |
|
|
not have any quote marks and would not be a valid C string. The
|
1547 |
|
|
configuration system is not yet able to perform the required validation
|
1548 |
|
|
so the following <TT
|
1549 |
|
|
CLASS="LITERAL"
|
1550 |
|
|
>#define</TT
|
1551 |
|
|
> would
|
1552 |
|
|
be generated in the configuration header file:</P
|
1553 |
|
|
><TABLE
|
1554 |
|
|
BORDER="5"
|
1555 |
|
|
BGCOLOR="#E0E0F0"
|
1556 |
|
|
WIDTH="70%"
|
1557 |
|
|
><TR
|
1558 |
|
|
><TD
|
1559 |
|
|
><PRE
|
1560 |
|
|
CLASS="PROGRAMLISTING"
|
1561 |
|
|
>#define CYGDAT_LIBC_STDIO_DEFAULT_CONSOLE /dev/ttydiag </PRE
|
1562 |
|
|
></TD
|
1563 |
|
|
></TR
|
1564 |
|
|
></TABLE
|
1565 |
|
|
><P
|
1566 |
|
|
>This is likely to cause a compile-time failure when building
|
1567 |
|
|
<SPAN
|
1568 |
|
|
CLASS="PRODUCTNAME"
|
1569 |
|
|
>eCos</SPAN
|
1570 |
|
|
>.</P
|
1571 |
|
|
><P
|
1572 |
|
|
>A quoted argument continues until the closing quote character
|
1573 |
|
|
is encountered, which means that it can span multiple lines. This
|
1574 |
|
|
can also be encountered in <SPAN
|
1575 |
|
|
CLASS="PRODUCTNAME"
|
1576 |
|
|
>eCos</SPAN
|
1577 |
|
|
> savefiles, for instance, in the <TT
|
1578 |
|
|
CLASS="LITERAL"
|
1579 |
|
|
>CYGDAT_UITRON_MEMPOOLVAR_EXTERNS</TT
|
1580 |
|
|
> example
|
1581 |
|
|
mentioned earlier. Newline or semicolon characters do not terminate
|
1582 |
|
|
the current command in such cases.</P
|
1583 |
|
|
><P
|
1584 |
|
|
>The Tcl interpreter supports much the same forms of backslash
|
1585 |
|
|
substitution as other common programming languages. Some backslash
|
1586 |
|
|
sequences such as <TT
|
1587 |
|
|
CLASS="LITERAL"
|
1588 |
|
|
>\n</TT
|
1589 |
|
|
> will
|
1590 |
|
|
be replaced by the appropriate character. The sequence <TT
|
1591 |
|
|
CLASS="LITERAL"
|
1592 |
|
|
>\\</TT
|
1593 |
|
|
> will
|
1594 |
|
|
be replaced by a single backslash. A backslash at the very end of
|
1595 |
|
|
a line will cause that backslash, the newline character, and any
|
1596 |
|
|
white space at the start of the next line to be replaced by a single
|
1597 |
|
|
space. Hence the following two Tcl commands are equivalent:</P
|
1598 |
|
|
><TABLE
|
1599 |
|
|
BORDER="5"
|
1600 |
|
|
BGCOLOR="#E0E0F0"
|
1601 |
|
|
WIDTH="70%"
|
1602 |
|
|
><TR
|
1603 |
|
|
><TD
|
1604 |
|
|
><PRE
|
1605 |
|
|
CLASS="PROGRAMLISTING"
|
1606 |
|
|
>puts “Hello\nworld\n”
|
1607 |
|
|
puts \
|
1608 |
|
|
“Hello
|
1609 |
|
|
world
|
1610 |
|
|
“</PRE
|
1611 |
|
|
></TD
|
1612 |
|
|
></TR
|
1613 |
|
|
></TABLE
|
1614 |
|
|
><P
|
1615 |
|
|
>In addition to quote and backslash characters, the Tcl interpreter
|
1616 |
|
|
treats square brackets, the <TT
|
1617 |
|
|
CLASS="LITERAL"
|
1618 |
|
|
>$</TT
|
1619 |
|
|
> character,
|
1620 |
|
|
and braces specially. Square brackets are used for command substitution,
|
1621 |
|
|
for example:</P
|
1622 |
|
|
><TABLE
|
1623 |
|
|
BORDER="5"
|
1624 |
|
|
BGCOLOR="#E0E0F0"
|
1625 |
|
|
WIDTH="70%"
|
1626 |
|
|
><TR
|
1627 |
|
|
><TD
|
1628 |
|
|
><PRE
|
1629 |
|
|
CLASS="PROGRAMLISTING"
|
1630 |
|
|
>puts “The answer is [expr 6 * 9]”</PRE
|
1631 |
|
|
></TD
|
1632 |
|
|
></TR
|
1633 |
|
|
></TABLE
|
1634 |
|
|
><P
|
1635 |
|
|
>When the Tcl interpreter encounters the square brackets it
|
1636 |
|
|
will treat the contents as another command that should be executed
|
1637 |
|
|
first, and the result of executing that is used when continuing
|
1638 |
|
|
to process the script. In this case the Tcl interpreter will execute
|
1639 |
|
|
the command <TT
|
1640 |
|
|
CLASS="LITERAL"
|
1641 |
|
|
>expr 6 * 9</TT
|
1642 |
|
|
>,
|
1643 |
|
|
yielding a result of 54, and then the Tcl interpreter will execute
|
1644 |
|
|
<TT
|
1645 |
|
|
CLASS="LITERAL"
|
1646 |
|
|
>puts “The answer is 54”</TT
|
1647 |
|
|
>. It should be noted that
|
1648 |
|
|
the interpreter contains only one level of substitution: if the
|
1649 |
|
|
result of performing command substitution performs further special
|
1650 |
|
|
characters such as square brackets then these will not be treated
|
1651 |
|
|
specially.</P
|
1652 |
|
|
><P
|
1653 |
|
|
>Command line substitution is very unlikely to prove useful
|
1654 |
|
|
in the context of an <SPAN
|
1655 |
|
|
CLASS="PRODUCTNAME"
|
1656 |
|
|
>eCos</SPAN
|
1657 |
|
|
> savefile, but it is part of the Tcl language
|
1658 |
|
|
and hence cannot be easily suppressed while reading in a savefile.
|
1659 |
|
|
As a result care has to be taken when savefile data involves square
|
1660 |
|
|
brackets. Consider the following:</P
|
1661 |
|
|
><TABLE
|
1662 |
|
|
BORDER="5"
|
1663 |
|
|
BGCOLOR="#E0E0F0"
|
1664 |
|
|
WIDTH="70%"
|
1665 |
|
|
><TR
|
1666 |
|
|
><TD
|
1667 |
|
|
><PRE
|
1668 |
|
|
CLASS="PROGRAMLISTING"
|
1669 |
|
|
> cdl_option CYGDAT_UITRON_MEMPOOLFIXED_EXTERNS {
|
1670 |
|
|
...
|
1671 |
|
|
user_value \
|
1672 |
|
|
“static char fpool1[ 2000 ],
|
1673 |
|
|
fpool2[ 2000 ];”
|
1674 |
|
|
...
|
1675 |
|
|
};</PRE
|
1676 |
|
|
></TD
|
1677 |
|
|
></TR
|
1678 |
|
|
></TABLE
|
1679 |
|
|
><P
|
1680 |
|
|
>The Tcl interpreter will interpret the square brackets as
|
1681 |
|
|
an attempt at command substitution and hence it will attempt to
|
1682 |
|
|
execute the command <TT
|
1683 |
|
|
CLASS="LITERAL"
|
1684 |
|
|
>2000</TT
|
1685 |
|
|
> with no
|
1686 |
|
|
arguments. No such command is defined by the Tcl language or by
|
1687 |
|
|
the savefile-related extensions provided by the configuration system,
|
1688 |
|
|
so this will result in an error when an attempt is made to read
|
1689 |
|
|
back the savefile. Instead it is necessary to backslash-escape the
|
1690 |
|
|
square brackets and thus suppress command substitution:</P
|
1691 |
|
|
><TABLE
|
1692 |
|
|
BORDER="5"
|
1693 |
|
|
BGCOLOR="#E0E0F0"
|
1694 |
|
|
WIDTH="70%"
|
1695 |
|
|
><TR
|
1696 |
|
|
><TD
|
1697 |
|
|
><PRE
|
1698 |
|
|
CLASS="PROGRAMLISTING"
|
1699 |
|
|
> cdl_option CYGDAT_UITRON_MEMPOOLFIXED_EXTERNS {
|
1700 |
|
|
...
|
1701 |
|
|
user_value \
|
1702 |
|
|
“static char fpool1\[ 2000 \],
|
1703 |
|
|
fpool2\[ 2000 \];”
|
1704 |
|
|
...
|
1705 |
|
|
}; </PRE
|
1706 |
|
|
></TD
|
1707 |
|
|
></TR
|
1708 |
|
|
></TABLE
|
1709 |
|
|
><P
|
1710 |
|
|
>Similarly the <TT
|
1711 |
|
|
CLASS="LITERAL"
|
1712 |
|
|
>$</TT
|
1713 |
|
|
> character
|
1714 |
|
|
is used in Tcl scripts to perform variable substitution:</P
|
1715 |
|
|
><TABLE
|
1716 |
|
|
BORDER="5"
|
1717 |
|
|
BGCOLOR="#E0E0F0"
|
1718 |
|
|
WIDTH="70%"
|
1719 |
|
|
><TR
|
1720 |
|
|
><TD
|
1721 |
|
|
><PRE
|
1722 |
|
|
CLASS="PROGRAMLISTING"
|
1723 |
|
|
>set x [expr 6 * 9]
|
1724 |
|
|
puts “The answer is $x” </PRE
|
1725 |
|
|
></TD
|
1726 |
|
|
></TR
|
1727 |
|
|
></TABLE
|
1728 |
|
|
><P
|
1729 |
|
|
>Variable substitution, like command substitution, is very
|
1730 |
|
|
unlikely to prove useful in the context of an <SPAN
|
1731 |
|
|
CLASS="PRODUCTNAME"
|
1732 |
|
|
>eCos</SPAN
|
1733 |
|
|
> savefile. Should
|
1734 |
|
|
it be necessary to have a <TT
|
1735 |
|
|
CLASS="LITERAL"
|
1736 |
|
|
>$</TT
|
1737 |
|
|
> character
|
1738 |
|
|
in configuration data then again a backslash escape needs to be
|
1739 |
|
|
used.</P
|
1740 |
|
|
><TABLE
|
1741 |
|
|
BORDER="5"
|
1742 |
|
|
BGCOLOR="#E0E0F0"
|
1743 |
|
|
WIDTH="70%"
|
1744 |
|
|
><TR
|
1745 |
|
|
><TD
|
1746 |
|
|
><PRE
|
1747 |
|
|
CLASS="PROGRAMLISTING"
|
1748 |
|
|
>cdl_option FOODAT_MONITOR_PROMPT {
|
1749 |
|
|
...
|
1750 |
|
|
user_value “\$ “
|
1751 |
|
|
...
|
1752 |
|
|
};</PRE
|
1753 |
|
|
></TD
|
1754 |
|
|
></TR
|
1755 |
|
|
></TABLE
|
1756 |
|
|
><P
|
1757 |
|
|
>Braces are used to collect a sequence of characters into a
|
1758 |
|
|
single argument, just like quotes. The difference is that variable,
|
1759 |
|
|
command and backslash substitution do not occur inside braces (with
|
1760 |
|
|
the sole exception of backslash substitution at the end of a line).
|
1761 |
|
|
So, for example, the <TT
|
1762 |
|
|
CLASS="LITERAL"
|
1763 |
|
|
>CYGDAT_UITRON_MEMPOOL_EXTERNFIXED_EXTERNS</TT
|
1764 |
|
|
> value
|
1765 |
|
|
could be written as:</P
|
1766 |
|
|
><TABLE
|
1767 |
|
|
BORDER="5"
|
1768 |
|
|
BGCOLOR="#E0E0F0"
|
1769 |
|
|
WIDTH="70%"
|
1770 |
|
|
><TR
|
1771 |
|
|
><TD
|
1772 |
|
|
><PRE
|
1773 |
|
|
CLASS="PROGRAMLISTING"
|
1774 |
|
|
>cdl_option CYGDAT_UITRON_MEMPOOLFIXED_EXTERNS {
|
1775 |
|
|
...
|
1776 |
|
|
user_value \
|
1777 |
|
|
{static char fpool1[ 2000 ],
|
1778 |
|
|
fpool2[ 2000 ];}
|
1779 |
|
|
...
|
1780 |
|
|
};</PRE
|
1781 |
|
|
></TD
|
1782 |
|
|
></TR
|
1783 |
|
|
></TABLE
|
1784 |
|
|
><P
|
1785 |
|
|
>The configuration system does not use this when generating
|
1786 |
|
|
savefiles because for simple edits of a savefile by inexperienced
|
1787 |
|
|
users the use of brace characters is likely to be a little bit more
|
1788 |
|
|
confusing than the use of quotes.</P
|
1789 |
|
|
><P
|
1790 |
|
|
>At this stage it is worth noting that the basic format of
|
1791 |
|
|
each configuration option in the savefile makes use of braces:</P
|
1792 |
|
|
><TABLE
|
1793 |
|
|
BORDER="5"
|
1794 |
|
|
BGCOLOR="#E0E0F0"
|
1795 |
|
|
WIDTH="70%"
|
1796 |
|
|
><TR
|
1797 |
|
|
><TD
|
1798 |
|
|
><PRE
|
1799 |
|
|
CLASS="PROGRAMLISTING"
|
1800 |
|
|
>cdl_option <name> {
|
1801 |
|
|
...
|
1802 |
|
|
};</PRE
|
1803 |
|
|
></TD
|
1804 |
|
|
></TR
|
1805 |
|
|
></TABLE
|
1806 |
|
|
><P
|
1807 |
|
|
>The configuration system extends the Tcl language with a small
|
1808 |
|
|
number of additional commands such as <TT
|
1809 |
|
|
CLASS="LITERAL"
|
1810 |
|
|
>cdl_option</TT
|
1811 |
|
|
>.
|
1812 |
|
|
These commands take two arguments, a name and a body, where the
|
1813 |
|
|
body consists of all the text between the braces. First a check
|
1814 |
|
|
is made that the specified option is actually present in the configuration.
|
1815 |
|
|
Then the body is executed in a recursive invocation of the Tcl interpreter,
|
1816 |
|
|
this time with additional commands such as <TT
|
1817 |
|
|
CLASS="LITERAL"
|
1818 |
|
|
>user_value</TT
|
1819 |
|
|
> and <TT
|
1820 |
|
|
CLASS="LITERAL"
|
1821 |
|
|
>value_source</TT
|
1822 |
|
|
>.
|
1823 |
|
|
If, after editing, the braces are not correctly matched up then
|
1824 |
|
|
the savefile will no longer be a valid Tcl script and errors will
|
1825 |
|
|
be reported when the savefile is loaded again.</P
|
1826 |
|
|
><P
|
1827 |
|
|
>Comments in Tcl scripts are introduced by a hash character <TT
|
1828 |
|
|
CLASS="LITERAL"
|
1829 |
|
|
>#</TT
|
1830 |
|
|
>.
|
1831 |
|
|
However, a hash character only introduces a comment if it occurs
|
1832 |
|
|
where a command is expected. Consider the following:</P
|
1833 |
|
|
><TABLE
|
1834 |
|
|
BORDER="5"
|
1835 |
|
|
BGCOLOR="#E0E0F0"
|
1836 |
|
|
WIDTH="70%"
|
1837 |
|
|
><TR
|
1838 |
|
|
><TD
|
1839 |
|
|
><PRE
|
1840 |
|
|
CLASS="PROGRAMLISTING"
|
1841 |
|
|
># This is a comment
|
1842 |
|
|
puts “Hello” # world </PRE
|
1843 |
|
|
></TD
|
1844 |
|
|
></TR
|
1845 |
|
|
></TABLE
|
1846 |
|
|
><P
|
1847 |
|
|
>The first line is a valid comment, since the hash character
|
1848 |
|
|
occurs right at the start where a command name is expected. The
|
1849 |
|
|
second line does not contain a comment. Instead it is an attempt
|
1850 |
|
|
to invoke the <TT
|
1851 |
|
|
CLASS="LITERAL"
|
1852 |
|
|
>puts</TT
|
1853 |
|
|
> command with
|
1854 |
|
|
three arguments: <TT
|
1855 |
|
|
CLASS="LITERAL"
|
1856 |
|
|
>Hello</TT
|
1857 |
|
|
>, <TT
|
1858 |
|
|
CLASS="LITERAL"
|
1859 |
|
|
>#</TT
|
1860 |
|
|
> and <TT
|
1861 |
|
|
CLASS="LITERAL"
|
1862 |
|
|
>world</TT
|
1863 |
|
|
>.
|
1864 |
|
|
These are not valid arguments for the <TT
|
1865 |
|
|
CLASS="LITERAL"
|
1866 |
|
|
>puts</TT
|
1867 |
|
|
> command
|
1868 |
|
|
so an error will be raised.</P
|
1869 |
|
|
><P
|
1870 |
|
|
>If the second line was rewritten as:</P
|
1871 |
|
|
><TABLE
|
1872 |
|
|
BORDER="5"
|
1873 |
|
|
BGCOLOR="#E0E0F0"
|
1874 |
|
|
WIDTH="70%"
|
1875 |
|
|
><TR
|
1876 |
|
|
><TD
|
1877 |
|
|
><PRE
|
1878 |
|
|
CLASS="PROGRAMLISTING"
|
1879 |
|
|
>puts “Hello”; # world</PRE
|
1880 |
|
|
></TD
|
1881 |
|
|
></TR
|
1882 |
|
|
></TABLE
|
1883 |
|
|
><P
|
1884 |
|
|
>then this is a valid Tcl script. The semicolon identifies
|
1885 |
|
|
the end of the current command, so the hash character occurs at
|
1886 |
|
|
a point where the next command would start and hence it is interpreted
|
1887 |
|
|
as the start of a comment.</P
|
1888 |
|
|
><P
|
1889 |
|
|
>This handling of comments can lead to subtle behaviour. Consider
|
1890 |
|
|
the following:</P
|
1891 |
|
|
><TABLE
|
1892 |
|
|
BORDER="5"
|
1893 |
|
|
BGCOLOR="#E0E0F0"
|
1894 |
|
|
WIDTH="70%"
|
1895 |
|
|
><TR
|
1896 |
|
|
><TD
|
1897 |
|
|
><PRE
|
1898 |
|
|
CLASS="PROGRAMLISTING"
|
1899 |
|
|
>cdl_option WHATEVER {
|
1900 |
|
|
# This is a comment }
|
1901 |
|
|
user_value 42
|
1902 |
|
|
...
|
1903 |
|
|
}</PRE
|
1904 |
|
|
></TD
|
1905 |
|
|
></TR
|
1906 |
|
|
></TABLE
|
1907 |
|
|
><P
|
1908 |
|
|
>Consider the way the Tcl interpreter processes this. The command
|
1909 |
|
|
name and the first argument do not pose any special difficulties.
|
1910 |
|
|
The opening brace is interpreted as the start of the next argument,
|
1911 |
|
|
which continues until a closing brace is encountered. In this case
|
1912 |
|
|
the closing brace occurs on the second line, so the second argument
|
1913 |
|
|
passed to <TT
|
1914 |
|
|
CLASS="LITERAL"
|
1915 |
|
|
>cdl_option</TT
|
1916 |
|
|
> is <TT
|
1917 |
|
|
CLASS="LITERAL"
|
1918 |
|
|
>\n # This is a comment</TT
|
1919 |
|
|
> . This second argument
|
1920 |
|
|
is processed in a recursive invocation of the Tcl interpreter and
|
1921 |
|
|
does not contain any commands, just a comment. Toplevel savefile
|
1922 |
|
|
processing then resumes, and the next command that is encountered
|
1923 |
|
|
is <TT
|
1924 |
|
|
CLASS="LITERAL"
|
1925 |
|
|
>user_value</TT
|
1926 |
|
|
>. Since the
|
1927 |
|
|
relevant savefile code is not currently processing a configuration
|
1928 |
|
|
option this is an error. Later on the Tcl interpreter would encounter
|
1929 |
|
|
a closing brace by itself, which is also an error. Fortunately this
|
1930 |
|
|
sequence of events is very unlikely to occur when editing generated
|
1931 |
|
|
savefiles.</P
|
1932 |
|
|
><P
|
1933 |
|
|
>This should be sufficient information about Tcl to allow for
|
1934 |
|
|
safe editing of <SPAN
|
1935 |
|
|
CLASS="PRODUCTNAME"
|
1936 |
|
|
>eCos</SPAN
|
1937 |
|
|
> savefiles. Further information is available
|
1938 |
|
|
from a wide variety of sources, for example the book <SPAN
|
1939 |
|
|
CLASS="emphasis"
|
1940 |
|
|
><I
|
1941 |
|
|
CLASS="EMPHASIS"
|
1942 |
|
|
>Tcl
|
1943 |
|
|
and the Tk Toolkit </I
|
1944 |
|
|
></SPAN
|
1945 |
|
|
>by John K Ousterhout.</P
|
1946 |
|
|
></DIV
|
1947 |
|
|
></DIV
|
1948 |
|
|
><DIV
|
1949 |
|
|
CLASS="NAVFOOTER"
|
1950 |
|
|
><HR
|
1951 |
|
|
ALIGN="LEFT"
|
1952 |
|
|
WIDTH="100%"><TABLE
|
1953 |
|
|
SUMMARY="Footer navigation table"
|
1954 |
|
|
WIDTH="100%"
|
1955 |
|
|
BORDER="0"
|
1956 |
|
|
CELLPADDING="0"
|
1957 |
|
|
CELLSPACING="0"
|
1958 |
|
|
><TR
|
1959 |
|
|
><TD
|
1960 |
|
|
WIDTH="33%"
|
1961 |
|
|
ALIGN="left"
|
1962 |
|
|
VALIGN="top"
|
1963 |
|
|
><A
|
1964 |
|
|
HREF="fine-grained-configuration.html"
|
1965 |
|
|
ACCESSKEY="P"
|
1966 |
|
|
>Prev</A
|
1967 |
|
|
></TD
|
1968 |
|
|
><TD
|
1969 |
|
|
WIDTH="34%"
|
1970 |
|
|
ALIGN="center"
|
1971 |
|
|
VALIGN="top"
|
1972 |
|
|
><A
|
1973 |
|
|
HREF="ecos-user-guide.html"
|
1974 |
|
|
ACCESSKEY="H"
|
1975 |
|
|
>Home</A
|
1976 |
|
|
></TD
|
1977 |
|
|
><TD
|
1978 |
|
|
WIDTH="33%"
|
1979 |
|
|
ALIGN="right"
|
1980 |
|
|
VALIGN="top"
|
1981 |
|
|
><A
|
1982 |
|
|
HREF="editing-the-sources.html"
|
1983 |
|
|
ACCESSKEY="N"
|
1984 |
|
|
>Next</A
|
1985 |
|
|
></TD
|
1986 |
|
|
></TR
|
1987 |
|
|
><TR
|
1988 |
|
|
><TD
|
1989 |
|
|
WIDTH="33%"
|
1990 |
|
|
ALIGN="left"
|
1991 |
|
|
VALIGN="top"
|
1992 |
|
|
>Fine-grained Configuration</TD
|
1993 |
|
|
><TD
|
1994 |
|
|
WIDTH="34%"
|
1995 |
|
|
ALIGN="center"
|
1996 |
|
|
VALIGN="top"
|
1997 |
|
|
><A
|
1998 |
|
|
HREF="manual-configuration.html"
|
1999 |
|
|
ACCESSKEY="U"
|
2000 |
|
|
>Up</A
|
2001 |
|
|
></TD
|
2002 |
|
|
><TD
|
2003 |
|
|
WIDTH="33%"
|
2004 |
|
|
ALIGN="right"
|
2005 |
|
|
VALIGN="top"
|
2006 |
|
|
>Editing the Sources</TD
|
2007 |
|
|
></TR
|
2008 |
|
|
></TABLE
|
2009 |
|
|
></DIV
|
2010 |
|
|
></BODY
|
2011 |
|
|
></HTML
|
2012 |
|
|
>
|