ecos-v3_0-branch: packages/hal/synth/arch/current/doc/synth.sgml annotate

annotate packages/hal/synth/arch/current/doc/synth.sgml @ 210:d2c90368aeef

Merge from eCos master repository on 2002-05-23-21:39:14-BST

author	jlarmour
date	Thu, 23 May 2002 22:59:51 +0000
parents	e0c0827131d1
children	7c1c8dc43ba1

rev	line source
208 e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	1 <!DOCTYPE part PUBLIC "-//OASIS//DTD DocBook V3.1//EN">
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	2
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	3 <!-- {{{ Banner -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	4
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	5 <!-- =============================================================== -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	6 <!-- -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	7 <!-- synth.sgml -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	8 <!-- -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	9 <!-- Synthetic target architectural documentation. -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	10 <!-- -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	11 <!-- =============================================================== -->
210 d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	12 #####ECOSGPLCOPYRIGHTBEGIN####
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	13 ## -------------------------------------------
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	14 ## This file is part of eCos, the Embedded Configurable Operating System.
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	15 ## Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	16 ##
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	17 ## eCos is free software; you can redistribute it and/or modify it under
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	18 ## the terms of the GNU General Public License as published by the Free
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	19 ## Software Foundation; either version 2 or (at your option) any later version.
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	20 ##
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	21 ## eCos is distributed in the hope that it will be useful, but WITHOUT ANY
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	22 ## WARRANTY; without even the implied warranty of MERCHANTABILITY or
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	23 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	24 ## for more details.
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	25 ##
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	26 ## You should have received a copy of the GNU General Public License along
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	27 ## with eCos; if not, write to the Free Software Foundation, Inc.,
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	28 ## 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	29 ##
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	30 ## As a special exception, if other files instantiate templates or use macros
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	31 ## or inline functions from this file, or you compile this file and link it
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	32 ## with other works to produce a work based on this file, this file does not
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	33 ## by itself cause the resulting work to be covered by the GNU General Public
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	34 ## License. However the source code for this file must still be made available
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	35 ## in accordance with section (3) of the GNU General Public License.
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	36 ##
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	37 ## This exception does not invalidate any other reasons why a work based on
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	38 ## this file might be covered by the GNU General Public License.
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	39 ##
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	40 ## Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	41 ## at http://sources.redhat.com/ecos/ecos-license/
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	42 ## -------------------------------------------
d2c90368aeef Merge from eCos master repository on 2002-05-23-21:39:14-BST jlarmour parents: 208 diff changeset	43 #####ECOSGPLCOPYRIGHTEND####
208 e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	44 <!-- =============================================================== -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	45 <!-- #####DESCRIPTIONBEGIN#### -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	46 <!-- -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	47 <!-- Author(s): bartv -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	48 <!-- Contact(s): bartv -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	49 <!-- Date: 2002/02/24 -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	50 <!-- Version: 0.01 -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	51 <!-- -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	52 <!-- ####DESCRIPTIONEND#### -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	53 <!-- =============================================================== -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	54
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	55 <!-- }}} -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	56
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	57 <part id="hal-synth-arch"><title>eCos Synthetic Target</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	58
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	59 <!-- {{{ Overview -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	60
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	61 <refentry id="synth">
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	62 <refmeta>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	63 <refentrytitle>Overview</refentrytitle>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	64 </refmeta>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	65 <refnamediv>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	66 <refname>Overview</refname>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	67 <refpurpose>The eCos synthetic target</refpurpose>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	68 </refnamediv>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	69
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	70 <refsect1 id="synth-description"><title>Description</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	71 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	72 Usually eCos runs on either a custom piece of hardware, specially
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	73 designed to meet the needs of a specific application, or on a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	74 development board of some sort that is available before the final
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	75 hardware. Such boards have a number of things in common:
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	76 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	77 <orderedlist>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	78 <listitem><para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	79 Obviously there has to be at least one processor to do the work.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	80 Usually this will be a 32-bit processor, but it can be smaller or
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	81 larger. Processor speed will vary widely, depending on the expected
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	82 needs of the application. However usually the exact processor being
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	83 used does not matter very much for most of the development process:
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	84 the use of languages such as C or C++ means that the compiler will
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	85 handle those details.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	86 </para></listitem>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	87 <listitem><para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	88 There needs to be memory for code and for data. A typical system will
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	89 have two different types of memory. There will be some non-volatile
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	90 memory such as flash, EPROM or masked ROM. There will also be some
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	91 volatile memory such as DRAM or SRAM. Often the code for the final
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	92 application will reside in the non-volatile memory and all of the RAM
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	93 will be available for data. However updating non-volatile memory
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	94 requires a non-trivial amount of effort, so for much of the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	95 development process it is more convenient to burn suitable firmware,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	96 for example RedBoot, into the non-volatile memory and then use that to
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	97 load the application being debugged into RAM, alongside the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	98 application data and a small area reserved for use by the firmware.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	99 </para></listitem>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	100 <listitem><para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	101 The platform must provide certain mimimal I/O facilities. Most eCos
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	102 configurations require a clock signal of some sort. There must also be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	103 some way of outputting diagnostics to the user, often but not always
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	104 via a serial port. Unless special debug hardware is being used, source
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	105 level debugging will require bidirectional communication between a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	106 host machine and the target hardware, usually via a serial port or an
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	107 ethernet device.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	108 </para></listitem>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	109 <listitem><para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	110 All the above is not actually very useful yet because there is no way
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	111 for the embedded device to interact with the rest of the world, except
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	112 by generating diagnostics. Therefore an embedded device will have
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	113 additional I/O hardware. This may be fairly standard hardware such as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	114 an ethernet or USB interface, or special hardware designed
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	115 specifically for the intended application, or quite often some
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	116 combination. Standard hardware such as ethernet or USB may be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	117 supported by eCos device drivers and protocol stacks, whereas the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	118 special hardware will be driven directly by application code.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	119 </para></listitem>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	120 </orderedlist>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	121 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	122 Much of the above can be emulated on a typical PC running Linux.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	123 Instead of running the embedded application being developed on a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	124 target board of some sort, it can be run as a Linux process. The
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	125 processor will be the PC's own processor, for example an x86, and the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	126 memory will be the process' address space. Some I/O facilities can be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	127 emulated through system calls. For example clock hardware can be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	128 emulated by setting up a <literal>SIGALRM</literal> signal, which will
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	129 cause the process to be interrupted at regular intervals. This
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	130 emulation of real hardware will not be particularly accurate, for
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	131 example the number of cpu cycles available to the eCos application
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	132 between clock ticks will vary widely depending on what else is running
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	133 on the PC, but for much development work it will be good enough.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	134 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	135 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	136 A key requirement for synthetic target code is that the embedded
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	137 application must not be linked with any of the standard Linux
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	138 libraries such as the GNU C library: that would lead to a confusing
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	139 situation where both eCos and the Linux libraries attempted to provide
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	140 functions such as <function>printf</function>. Instead the synthetic
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	141 target support must be implemented directly on top of the Linux
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	142 kernels' system call interface. For example, the kernel provides a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	143 system call for write operations. The actual function
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	144 <function>write</function> is implemented in the system's C library,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	145 but all it does is move its arguments on to the stack or into certain
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	146 registers and then execute a special trap instruction such as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	147 <literal>int 0x80</literal>. When this instruction is executed
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	148 control transfers into the kernel, which will validate the arguments
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	149 and perform the appropriate operation. Now, a synthetic target
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	150 application cannot be linked with the system's C library. Instead it
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	151 contains a function <function>cyg_hal_sys_write</function> which, like
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	152 the C library's <function>write</function> function, pushes its
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	153 arguments on to the stack and executes the trap instruction. The Linux
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	154 kernel cannot tell the difference, so it will perform the I/O
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	155 operation requested by the synthetic target. With appropriate
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	156 knowledge of what system calls are available, this makes it possible
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	157 to emulate the required I/O facilities. For example diagnostic output
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	158 can be achieved by a <function>cyg_hal_sys_write</function> system
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	159 call using file descriptor 1, which corresponds to stdout.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	160 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	161 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	162 In many ways developing for the synthetic target is no different from
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	163 developing for real embedded targets. eCos must be configured
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	164 appropriately: selecting a suitable target such as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	165 <userinput>i386linux</userinput> will cause the configuration system
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	166 to load the appropriate packages for this hardware; this includes an
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	167 architectural HAL package and a platform-specific package; the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	168 architectural package contains generic code applicable to all Linux
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	169 platforms, whereas the platform package is for specific Linux
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	170 implementations such as the x86 version and contains any
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	171 processor-specific code. Selecting this target will also bring in some
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	172 device driver packages. Other aspects of the configuration such as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	173 which API's are supported are determined by the template, by adding
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	174 and removing packages, and by fine-grained configuration.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	175 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	176 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	177 In other ways developing for the synthetic target can be much easier
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	178 than developing for a real embedded target. For example there is no
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	179 need to worry about building and installing suitable firmware on the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	180 target hardware, and then downloading and debugging the actual
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	181 application over a serial line or a similar connection. Instead an
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	182 eCos application built for the synthetic target is mostly
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	183 indistinguishable from an ordinary Linux program. It can be run simply
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	184 by typing the name of the executable file at a shell prompt.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	185 Alternatively you can debug the application using whichever version of
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	186 gdb is provided by your Linux distribution. There is no need to build
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	187 or install special toolchains. Essentially using the synthetic target
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	188 means that the various problems associated with real embedded hardware
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	189 can be bypassed for much of the development process.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	190 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	191 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	192 The eCos synthetic target provides emulation, not simulation. It is
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	193 possible to run eCos in suitable architectural simulators but that
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	194 involves a rather different approach to software development. For
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	195 example, when running eCos on the psim PowerPC simulator you need
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	196 appropriate cross-compilation tools that allow you to build PowerPC
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	197 executables. These are then loaded into the simulator which interprets
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	198 every instruction and attempts to simulate what would happen if the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	199 application were running on real hardware. This involves a lot of
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	200 processing overhead, but depending on the functionality provided by
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	201 the simulator it can give very accurate results. When developing for
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	202 the synthetic target the executable is compiled for the PC's own
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	203 processor and will be executed at full speed, with no need for a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	204 simulator or special tools. This will be much faster and somewhat
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	205 simpler than using an architectural simulator, but no attempt is made
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	206 to accurately match the behaviour of a real embedded target.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	207 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	208 <note><para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	209 Support for emulating standard hardware such as ethernet is not yet
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	210 available in the current release of the eCos synthetic target code,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	211 but is planned for future versions. Emulating application-specific
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	212 custom hardware is rather more difficult since there is no way of
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	213 knowing just what strange hardware a particular application might
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	214 need, but the I/O mechanisms planned should allow for
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	215 application-specific extensions.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	216 </para></note>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	217 </refsect1>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	218
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	219 <refsect1 id="synth-tools"><title>Toolchain</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	220 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	221 When developing eCos applications for a normal embedded target it is
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	222 necessary to use a suitable cross-compiler and related tools such as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	223 the linker. Developing for the synthetic target is easier because you
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	224 can just use the standard GNU tools (gcc, g++, ld, …) which
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	225 were provided with your Linux distribution, or which you used to build
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	226 your own Linux setup. Any reasonably recent version of the tools, for
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	227 example gcc 2.96(Red Hat) as shipped with Red Hat Linux 7, should be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	228 sufficient.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	229 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	230 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	231 There is one important limitation when using these tools: current gdb
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	232 will not support debugging of eCos threads on the synthetic target. As
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	233 far as gdb is concerned a synthetic target application is also
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	234 indistinguishable from a normal Linux application, so it assumes that
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	235 any threads will be created by calls to the Linux
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	236 <function>pthread_create</function> function provided by the C
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	237 library. Obviously this is not the case since the application is never
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	238 linked with that library. Therefore gdb never notices the eCos thread
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	239 mechanisms and assumes the application is single-threaded. Fixing this
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	240 is possible but would involve non-trivial changes to gdb.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	241 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	242 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	243 Theoretically it is possible to develop synthetic target applications
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	244 on, for example, a PC running Windows and then run the resulting
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	245 executables on another machine that runs Linux. This is rarely useful:
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	246 if a Linux machine is available then usually that machine will also be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	247 used for building ecos and the application. However, if for some
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	248 reason it is necessary or desirable to build on another machine then
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	249 this requires a suitable cross-compiler and related tools. If the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	250 application will be running on a typical PC with an x86 processor then
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	251 a suitable configure triplet would be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	252 <userinput>i686-pc-linux-gnu</userinput>. The installation
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	253 instructions for the various GNU tools should be consulted for further
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	254 information.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	255 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	256 </refsect1>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	257
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	258 <refsect1 id="synth-hardware"><title>Hardware Preparation</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	259 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	260 Preparing a real embedded target for eCos development can be tricky.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	261 Often the first step is to install suitable firmware, usually RedBoot.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	262 This means creating and building a special configuration for eCos with
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	263 the RedBoot template, then somehow updating the target's flash chips
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	264 with the resulting RedBoot image. Typically it will also be necessary
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	265 to get a working serial connection, and possibly set up ethernet as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	266 well. Although usually none of the individual steps are particularly
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	267 complicated, there are plenty of ways in which things can go wrong and
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	268 it can be hard to figure out what is actually happening. Of course
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	269 some board manufacturers make life easier for their developers by
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	270 shipping hardware with RedBoot preinstalled, but even then it is still
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	271 necessary to set up communication between host and target.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	272 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	273 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	274 None of this is applicable to the synthetic target. Instead you can
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	275 just build a normal eCos configuration, link your application with the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	276 resulting libraries, and you end up with an executable that you can
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	277 run directly on your Linux machine or via gdb. A useful side effect of
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	278 this is that application development can start before any real
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	279 embedded hardware is actually available.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	280 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	281 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	282 Typically the memory map for a synthetic target application will be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	283 set up such that there is a read-only ROM region containing all the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	284 code and constant data, and a read-write RAM region for the data. The
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	285 default locations and sizes of these regions depend on the specific
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	286 platform being used for development. Note that the application always
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	287 executes out of ROM: on a real embedded target much of the development
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	288 would involve running RedBoot firmware there, with application code
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	289 and data loaded into RAM; usually this would change for the final
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	290 system; the firmware would be removed; and the application itself
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	291 would execute from ROM and perform the appropriate hardware
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	292 initialization. Therefore the synthetic target actually emulates the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	293 behaviour of the final system, not the development environment.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	294 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	295 </refsect1>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	296
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	297 </refentry>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	298
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	299 <!-- }}} -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	300 <!-- {{{ System calls -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	301
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	302 <refentry id="synth-syscalls">
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	303 <refmeta>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	304 <refentrytitle>System Calls</refentrytitle>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	305 </refmeta>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	306
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	307 <refnamediv>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	308 <refname>cyg_hal_sys_xyz</refname>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	309 <refpurpose>Access Linux system facilities</refpurpose>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	310 </refnamediv>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	311
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	312 <refsynopsisdiv>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	313 <funcsynopsis>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	314 <funcsynopsisinfo>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	315 #include <cyg/hal/hal_io.h
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	316 </funcsynopsisinfo>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	317 <funcprototype>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	318 <funcdef>int <function>cyg_hal_sys_xyz</function></funcdef>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	319 <varargs>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	320 </funcprototype>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	321 </funcsynopsis>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	322 </refsynopsisdiv>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	323
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	324 <refsect1 id="synth-syscalls-description"><title>Description</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	325 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	326 On a real embedded target eCos interacts with the hardware by peeking
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	327 and poking various registers, manipulating special regions of memory,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	328 and so on. The synthetic target does not access hardware directly.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	329 Instead I/O and other operations are emulated by making appropriate
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	330 Linux system calls. The HAL package exports a number of functions
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	331 which allow other packages, or even application code, to make these
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	332 same system calls. However this facility must be used with care: any
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	333 code which calls, for example, <function>cyg_hal_sys_write</function>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	334 will only ever run on the synthetic target; that functionality is
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	335 obviously not provided on any real hardware because there is no
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	336 underlying Linux kernel to implement it.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	337 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	338 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	339 The synthetic target only provides a subset of the available system
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	340 calls, specifically those calls which have proved useful to implement
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	341 I/O emulation. This subset can be extended fairly easily if necessary.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	342 All of the available calls, plus associated data structures and
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	343 macros, are defined in the header file <filename
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	344 class="headerfile">cyg/hal/hal_io.h</filename>. There is a simple
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	345 convention: given a Linux system call such as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	346 <function>open</function>, the synthetic target will prefix
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	347 <literal>cyg_hal_sys</literal> and provide a function with that name.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	348 The second argument to the <function>open</function> system call is
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	349 a set of flags such as <constant>O_RDONLY</constant>, and the header
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	350 file will define a matching constant
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	351 <constant>CYG_HAL_SYS_O_RDONLY</constant>. There are also data
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	352 structures such as <structname>cyg_hal_sys_sigset_t</structname>,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	353 matching the Linux data structure <structname>sigset_t</structname>.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	354 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	355 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	356 In most cases the functions provided by the synthetic target behave as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	357 per the documentation for the Linux system calls, and section 2 of the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	358 Linux man pages can be consulted for more information. There is one
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	359 important difference: typically the documentation will say that a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	360 function returns <literal>-1</literal> to indicate an error, with the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	361 actual error code held in <varname>errno</varname>; the actual
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	362 underlying system call and hence the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	363 <function>cyg_hal_sys_xyz</function> provided by eCos instead returns
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	364 a negative number to indicate an error, with the absolute value of
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	365 that number corresponding to the error code; usually it is the C
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	366 library which handles this and manipulates errno, but of course
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	367 synthetic target applications are not linked with that Linux library.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	368 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	369 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	370 However, there are some exceptions. The Linux kernel has evolved over
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	371 the years, and some of the original system call interfaces are no
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	372 longer appropriate. For example the original
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	373 <function>select</function> system call has been superseded by
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	374 <function>_newselect</function>, and that is what the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	375 <function>select</function> function in the C library actually uses.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	376 The old call is still available to preserve binary compatibility but,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	377 like the C library, eCos makes use of the new one because it provides
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	378 the appropriate functionality. In an attempt to reduce confusion the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	379 eCos function is called <function>cyg_hal_sys__newselect</function>,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	380 in other words it matches the official system call naming scheme. The
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	381 authoritive source of information on such matters is the Linux kernel
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	382 sources themselves, and especially its header files.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	383 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	384 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	385 eCos packages and applications should never
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	386 <literal>#include</literal> Linux header files directly. For example,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	387 doing a <literal>#include </usr/include/fcntl.h></literal>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	388 to access additional macros or structure definitions, or alternatively
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	389 manipulating the header file search path, will lead to problems
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	390 because the Linux header files are likely to duplicate and clash with
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	391 definitions in the eCos headers. Instead the appropriate functionality
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	392 should be extracted from the Linux headers and moved into either
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	393 <filename class="headerfile">cyg/hal/hal_io.h</filename> or into
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	394 application code, with suitable renaming to avoid clashes with eCos
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	395 names. Users should be aware that large-scale copying may involve
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	396 licensing complications.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	397 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	398 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	399 Adding more system calls is usually straightforward and involves
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	400 adding one or more lines to the platform-specific file in the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	401 appropriate platform HAL, for example
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	402 <filename>syscall-i386-linux-1.0.S</filename>. However it is necessary
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	403 to do some research first about the exact interface implemented by the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	404 system call, because of issues such as old system calls that have been
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	405 superseded. The required information can usually be found fairly
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	406 easily by searching through the Linux kernel sources and possibly the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	407 GNU C library sources.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	408 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	409 </refsect1>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	410 </refentry>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	411
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	412 <!-- }}} -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	413 <!-- {{{ Porting -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	414
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	415 <refentry id="synth-porting">
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	416 <refmeta>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	417 <refentrytitle>Porting</refentrytitle>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	418 </refmeta>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	419 <refnamediv>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	420 <refname>Porting</refname>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	421 <refpurpose>The eCos synthetic target</refpurpose>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	422 </refnamediv>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	423
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	424 <refsect1 id="synth-porting-description"><title>Description</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	425 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	426 The initial development effort of the eCos synthetic target happened
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	427 on x86 Linux machines. Porting to other platforms involves addressing
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	428 a number of different issues. Some ports should be fairly
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	429 straightforward, for example a port to Linux on a processor other than
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	430 an x86. Porting to Unix or Unix-like operating systems other than
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	431 Linux may be possible, but would involve more effort. Porting to a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	432 completely different operating system such as Windows would be very
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	433 difficult. The text below completes the eCos Porting Guide.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	434 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	435 </refsect1>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	436
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	437 <refsect1 id="synth-porting-linux"><title>Other Linux Platforms</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	438 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	439 Porting the synthetic target to a Linux platform that uses a processor
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	440 other than x86 should be straightforward. The simplest approach is to
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	441 copy the existing <filename class="directory">i386linux</filename>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	442 directory tree in the <filename class="directory">hal/synth</filename>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	443 hierarchy, then rename and edit the ten or so files in this package.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	444 Most of the changes should be pretty obvious, for example on a 64-bit
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	445 processor some new data types will be needed in the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	446 <filename>basetype.h</filename> header file. It will also be necessary
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	447 to update the toplevel <filename>ecos.db</filename> database with an
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	448 entry for the new HAL package, and a new target entry will be needed
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	449 as well.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	450 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	451 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	452 Obviously a different processor will have different register sets
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	453 and calling conventions, so the code for saving and restoring thread
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	454 contexts and for implementing <function>setjmp</function> and
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	455 <function>longjmp</function> will need to be updated. The exact way of
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	456 performing Linux system calls will also vary: on i386linux this
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	457 usually involves pushing some registers on the stack and then
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	458 executing an <literal>int 0x080</literal> trap instruction, but
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	459 on a different processor the arguments might be passed in registers
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	460 instead and certainly a different trap instruction will be used. The
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	461 startup code is also written in assembler, but needs to do little more
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	462 than jump to the main <function>linux_entry</function> function
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	463 provided by the architectural synthetic target HAL package.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	464 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	465 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	466 The header file <filename>hal_io.h</filename> provided by the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	467 architectural HAL package provides various structure definitions,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	468 function prototypes, and macros related to system calls. These are
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	469 correct for i386linux, but there may be problems on other processors.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	470 For example a structure field that is currently defined as a 32-bit
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	471 number may in fact may be a 64-bit number instead.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	472 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	473 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	474 The synthetic target's memory map is defined in two files in the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	475 <filename class="directory">include/pkgconf</filename> subdirectory.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	476 For x86 the default memory map involves eight megabytes of read-only
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	477 memory for the code at location 0x1000000 and another eight megabytes
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	478 for data at 0x2000000. These address ranges may be reserved for other
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	479 purposes on the new architecture, so may need changing. There may be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	480 some additional areas of memory allocated by the system for other
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	481 purposes, for example the startup stack and any environment variables,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	482 but usually eCos applications can and should ignore those.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	483 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	484 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	485 Other HAL functionality such as interrupt handling, diagnostics, and
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	486 the system clock are provided by the architectural HAL package and
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	487 should work on different processors with few if any changes.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	488 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	489 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	490 When porting to other processors, a number of sources of information
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	491 are likely to prove useful. Obviously the Linux kernel sources and
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	492 header files constitute the ultimate authority on how things work at
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	493 the system call level. The GNU C library sources may also prove very
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	494 useful: for a normal Linux application it is the C library that
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	495 provides the startup code and the system call interface.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	496 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	497 </refsect1>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	498
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	499 <refsect1 id="synth-porting-unix"><title>Other Unix Platforms</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	500 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	501 Porting to a Unix or Unix-like operating system other than Linux would
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	502 be somewhat more involved. The first requirement involves toolchains:
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	503 the GNU compilers, gcc and g++, must definitely be used; use of other
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	504 GNU tools such as the linker may be needed as well, because eCos
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	505 depends on functionality such as prioritizing C++ static constructors,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	506 and other linkers may not implement this or may implement it in a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	507 different and incompatible way. A closely related requirement is the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	508 use of ELF format for binary executables: if the operating system
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	509 still uses an older format such as COFF then there are likely to be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	510 problems because they do not provide the flexibility required by eCos.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	511 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	512 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	513 In the architectural HAL there should be very little code that is
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	514 specific to Linux. Instead the code should work on any operating
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	515 system that provides a reasonable implementation of the POSIX
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	516 standard. There may be some problems with program startup, but those
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	517 could be handled at the architectural level. Some changes may also be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	518 required to the exception handling code. However one file which will
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	519 present a problem is <filename>hal_io.h</filename>, which contains
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	520 various structure definitions and macros used with the system call
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	521 interface. It is likely that many of these definitions will need
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	522 changing, and it may well be appropriate to implement variant HAL
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	523 packages for the different operating systems where this information
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	524 can be separated out. Another possible problem is that the generic
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	525 code assumes that system calls such as
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	526 <function>cyg_hal_sys_write</function> are available. On an operating
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	527 system other than Linux it is possible that some of these are not
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	528 simple system calls, and instead wrapper functions will need to be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	529 implemented at the variant HAL level.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	530 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	531 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	532 The remaining porting task is to implement one or more platform HAL
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	533 packages, one per processor type that is supported. This should
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	534 involve much the same work as a port to <link
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	535 linkend="synth-porting-linux">another processor running Linux</link>.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	536 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	537 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	538 When using other Unix operating systems the kernel source code may not
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	539 be available, which would make any porting effort more challenging.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	540 However there is still a good chance that the GNU C library will have
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	541 been ported already, so its source code may contain much useful
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	542 information.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	543 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	544 <caution><para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	545 Users should be aware that future enhancements to the synthetic target
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	546 code, especially in areas related to I/O, may be much more closely
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	547 tied to Linux. For example access to ethernet facilities might be
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	548 implemented using the <literal>PF_PACKET</literal> socket address
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	549 family, or the virtual tunnelling interface. Porting such code to
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	550 other Unix operating systems may prove rather more difficult.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	551 </para></caution>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	552 </refsect1>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	553
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	554 <refsect1 id="synth-porting-other"><title>Windows Platforms</title>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	555 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	556 Porting the current synthetic target code to some version of Windows
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	557 or to another non-Unix platform is likely to prove very difficult. The
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	558 first hurdle that needs to be crossed is the file format for binary
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	559 executables: current Windows implementations do not use ELF, instead
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	560 they use their own format PE which is a variant of the rather old and
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	561 limited COFF format. It may well prove easier to first write an ELF
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	562 loader for Windows executables, rather than try to get eCos to work
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	563 within the constraints of PE. Of course that introduces new problems,
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	564 for example existing source-level debuggers will still expect
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	565 executables to be in PE format.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	566 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	567 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	568 Under Linux a synthetic target application is not linked with the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	569 system's C library or any other standard system library. That would
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	570 cause confusion, for example both eCos and the system's C library
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	571 might try to define the <function>printf</function> function, and
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	572 introduce complications such as working with shared libraries. For
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	573 much the same reasons, a synthetic target application under Windows
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	574 should not be linked with any Windows DLL's. If an ELF loader has been
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	575 specially written then this may not be much of a problem.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	576 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	577 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	578 The next big problem is the system call interface. Under Windows
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	579 system calls are generally made via DLL's, and it is not clear that
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	580 the underlying trap mechanism is well-documented or consistent between
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	581 different releases of Windows.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	582 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	583 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	584 The current code depends on the operating system providing an
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	585 implementation of POSIX signal handling. This is used for I/O
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	586 purposes, for example <literal>SIGALRM</literal> is used for the
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	587 system clock, and for exceptions. It is not known what equivalent
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	588 functionality is available under Windows.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	589 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	590 <para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	591 Given the above problems a port of the synthetic target to Windows may
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	592 or may not be technically feasible, but it would certainly require a
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	593 very large amount of effort.
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	594 </para>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	595 </refsect1>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	596
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	597 </refentry>
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	598
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	599 <!-- }}} -->
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	600
e0c0827131d1 Merge from eCos master repository on 2002-05-20-20:11:54-BST jlarmour parents: diff changeset	601 </part>

Mercurial > ecos-v3_0-branch

annotate packages/hal/synth/arch/current/doc/synth.sgml @ 210:d2c90368aeef