+++ /dev/null
-<!-- 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
->Architecture, Variant and Platform</TITLE
-><meta name="MSSmartTagsPreventParsing" content="TRUE">
-<META
-NAME="GENERATOR"
-CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
-"><LINK
-REL="HOME"
-TITLE="eCos Reference Manual"
-HREF="ecos-ref.html"><LINK
-REL="UP"
-TITLE="The eCos Hardware Abstraction Layer (HAL)"
-HREF="the-ecos-hardware-abstraction-layer.html"><LINK
-REL="PREVIOUS"
-TITLE="Introduction"
-HREF="hal-introduction.html"><LINK
-REL="NEXT"
-TITLE="General principles"
-HREF="hal-general-principles.html"></HEAD
-><BODY
-CLASS="CHAPTER"
-BGCOLOR="#FFFFFF"
-TEXT="#000000"
-LINK="#0000FF"
-VLINK="#840084"
-ALINK="#0000FF"
-><DIV
-CLASS="NAVHEADER"
-><TABLE
-SUMMARY="Header navigation table"
-WIDTH="100%"
-BORDER="0"
-CELLPADDING="0"
-CELLSPACING="0"
-><TR
-><TH
-COLSPAN="3"
-ALIGN="center"
->eCos Reference Manual</TH
-></TR
-><TR
-><TD
-WIDTH="10%"
-ALIGN="left"
-VALIGN="bottom"
-><A
-HREF="hal-introduction.html"
-ACCESSKEY="P"
->Prev</A
-></TD
-><TD
-WIDTH="80%"
-ALIGN="center"
-VALIGN="bottom"
-></TD
-><TD
-WIDTH="10%"
-ALIGN="right"
-VALIGN="bottom"
-><A
-HREF="hal-general-principles.html"
-ACCESSKEY="N"
->Next</A
-></TD
-></TR
-></TABLE
-><HR
-ALIGN="LEFT"
-WIDTH="100%"></DIV
-><DIV
-CLASS="CHAPTER"
-><H1
-><A
-NAME="HAL-ARCHITECTURE-VARIANT-AND-PLATFORM">Chapter 7. Architecture, Variant and Platform</H1
-><P
->We have identified three levels at which the HAL must operate.</P
-><P
-></P
-><UL
-><LI
-><P
-> The <I
-CLASS="FIRSTTERM"
->architecture
- HAL</I
-> abstracts the basic CPU architecture and includes
- things like interrupt delivery, context switching, CPU startup
- etc.
- </P
-></LI
-><LI
-><P
-> The <I
-CLASS="FIRSTTERM"
->variant HAL</I
->
- encapsulates features of the CPU variant such as caches, MMU and
- FPU features. It also deals with any on-chip peripherals such as
- memory and interrupt controllers. For architectural variations,
- the actual implementation of the variation is often in the
- architectural HAL, and the variant HAL simply provides the correct
- configuration definitions.
- </P
-></LI
-><LI
-><P
-> The <I
-CLASS="FIRSTTERM"
->platform HAL</I
->
- abstracts the properties of the current platform and includes
- things like platform startup, timer devices, I/O register access
- and interrupt controllers.
- </P
-></LI
-></UL
-><P
->The boundaries between these three HAL levels are necessarily blurred
-since functionality shifts between levels on a target-by-target basis.
-For example caches and MMU may be either an architecture feature or a
-variant feature. Similarly, memory and interrupt controllers may be
-on-chip and in the variant HAL, or off-chip and in the platform HAL.</P
-><P
->Generally there is a separate package for each of the architecture,
-variant and package HALs for a target. For some of the older targets,
-or where it would be essentially empty, the variant HAL is omitted.</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="hal-introduction.html"
-ACCESSKEY="P"
->Prev</A
-></TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-><A
-HREF="ecos-ref.html"
-ACCESSKEY="H"
->Home</A
-></TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
-><A
-HREF="hal-general-principles.html"
-ACCESSKEY="N"
->Next</A
-></TD
-></TR
-><TR
-><TD
-WIDTH="33%"
-ALIGN="left"
-VALIGN="top"
->Introduction</TD
-><TD
-WIDTH="34%"
-ALIGN="center"
-VALIGN="top"
-><A
-HREF="the-ecos-hardware-abstraction-layer.html"
-ACCESSKEY="U"
->Up</A
-></TD
-><TD
-WIDTH="33%"
-ALIGN="right"
-VALIGN="top"
->General principles</TD
-></TR
-></TABLE
-></DIV
-></BODY
-></HTML
->
\ No newline at end of file
projects / karo-tx-redboot.git / blobdiff