source: rtems/c/src/lib/libbsp/bare/README @ 3299388d

4.104.114.84.95
Last change on this file since 3299388d was 28e7d7fa, checked in by Joel Sherrill <joel.sherrill@…>, on Aug 20, 1998 at 10:04:22 PM

Patches from Eric Norum

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File size: 4.3 KB
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1#
2#  $Id$
3#
4
5#
6# Please send any comments, improvements, or bug reports to:
7#       Chris Johns
8#       Objective Design Systems
9#       35 Cairo Street
10#       Cammeray
11#       Sydney, NSW 2062
12# ccj@acm.org
13#
14
15#
16# Overview
17# ~~~~~~~~
18# This board support package is not a board support package at all, but
19# a means to build the RTEMS kernel without using a specific BSP.
20#
21# You should be able to build to build this BSP for any cpu type.
22#
23# You must provide the standard BSP type functions and support yourself
24# externally to RTEMS.
25#
26# This BSP is intended to be used by people who fit one or more of the
27# categories below :
28#
29# 1) using custom hardware of little use or interest to others. If you
30#    intend to use hardware available to others, please create a BSP
31#    and send to OARCorp.
32#
33# 2) production code cannot depend on software which can change. BSP code
34#    can change with-out notice, while RTEMS has very tightly defined
35#    interfaces which do not change.
36#
37# 3) the need to extend or change an existing BSP in ways which are not
38#    of interest to others or the BSP maintainer.
39#
40# I fit all the above.
41#
42# Issues
43# ~~~~~~
44# I do not consider the bare BSP as a starting point for RTEMS. The
45# BSP code integrated into the RTEMS build tree has the advantage of
46# building all the test and sample code. The sample and test code is
47# important for validatation of your tools, and getting your BSP
48# working correctly.
49#
50# Once you gain experience with RTEM and your application matures the
51# need to break the BSP code out from the kernel becomes important. It
52# is at this point in time that the bare BSP becomes useful.
53#
54# Once free you are able to upgrade without the worry of makefile or
55# build tree changes which can break your BSP.
56#
57# How To Configure
58# ~~~~~~~~~~~~~~~~
59# RTEMS requires you to select a BSP inorder to build the kernel.
60# If you take a close look at a BSP which is closest to your
61# needs you will find somewhere the CPU model and CPU compile
62# flags are specified. This is the only piece of information
63# required by the kernel inorder for it to build.
64#
65# This highlights the clean design of the kernel and its
66# independence from the particulars of target hardware.
67#
68# The CPU model is the RTEMS model and usually tries to match with
69# the GCC model. There are variations on some processors. If you are
70# unsure please ask on the RTEMS list. Someone will know (I hope).
71#
72# The CPU flags allow you to select specific operating modes for
73# GCC. For example the PowerPC has specific flags to control various
74# cache resouces. Another example is the 68000 family of embedded
75# processor do not have FPU hardware and require software emulation.
76#
77# An example configuration command line is:
78#
79#  ../rtems-4.0/configure  --target=m68k-rtems \
80#                          --prefix=/ods/egcs/test \
81#                          --enable-cxx \
82#                          --enable-gmake-print-directory \
83#                          --disable-tests \
84#                          --disable-posix \
85#                          --enable-networking \
86#                          --enable-bare-cpu-cflags=-mcpu32 \
87#                          --enable-bare-cpu-model=mcpu32 \
88#                          --enable-rtemsbsp=bare
89#
90# Building RTEMS
91# ~~~~~~~~~~~~~~
92# You are required to do nothing special here. Just follow the documented
93# steps. The samples are built but no linking occurs. The link command
94# is stubbed out to produce a Unix shell script.
95#
96# After installation you will find a directory called 'bare'. The nature
97# of the RTEMS build system means the bare BSP will only install into the
98# the bare directory under the specifed configuration prefix.
99#
100# I therefore suggest you move the directory to another name. This allows
101# you to make and install another bare BSP for a different variant of
102# CPU without over writing the last installed variant.
103#
104# I have provided a script file I use to configure and build RTEMS
105# from the arcihve. Take a copy and use it if you find it useful.
106#
107# Creating an Application.
108# ~~~~~~~~~~~~~~~~~~~~~~~~
109# This is something which is usually specific to your local environment.
110# The bare BSP does not lock you into any specific makefile or build
111# system. A couple of suggestions are:
112#
113#   o Get the sample bare BSP application, or
114#   o Watch RTEMS build a BSP which is closest to yours and copy
115#     the command lines used.
116#
117
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