forked from Imagelibrary/rtems
8d7393ad5f
* BSP_TIMES, ChangeLog, Makefile.am, arm.texi, bsp.t, callconv.t, cpumodel.t, cputable.t, fatalerr.t, intr_NOTIMES.t, memmodel.t, preface.texi, stamp-vti, timeBSP.t, timing.texi, version.texi, wksheets.texi: New files as ARM supplement initial version added.
39 lines
1.3 KiB
Perl
39 lines
1.3 KiB
Perl
@c
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@c COPYRIGHT (c) 1988-2002.
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@c On-Line Applications Research Corporation (OAR).
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@c All rights reserved.
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@c
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@c $Id$
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@c
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@chapter Memory Model
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@section Introduction
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A processor may support any combination of memory
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models ranging from pure physical addressing to complex demand
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paged virtual memory systems. RTEMS supports a flat memory
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model which ranges contiguously over the processor's allowable
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address space. RTEMS does not support segmentation or virtual
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memory of any kind. The appropriate memory model for RTEMS
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provided by the targeted processor and related characteristics
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of that model are described in this chapter.
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@section Flat Memory Model
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Members of the ARM family newer than Version 3 support a flat
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32-bit address space with addresses ranging from 0x00000000 to
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0xFFFFFFFF (4 gigabytes). Each address is represented by a
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32-bit value and is byte addressable.
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The address may be used to reference a
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single byte, word (2-bytes), or long word (4 bytes). Memory
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accesses within this address space are performed in the endian
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mode that the processor is configured for. In general, ARM
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processors are used in little endian mode.
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Some of the ARM family members such as the
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920 and 720 include an MMU and thus support virtual memory and
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segmentation. RTEMS does not support virtual memory or
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segmentation on any of the ARM family members.
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