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40 lines
1.4 KiB
Perl
40 lines
1.4 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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The XXX family supports a flat 32-bit address
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space with addresses ranging from 0x00000000 to 0xFFFFFFFF (4
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gigabytes). Each address is represented by a 32-bit value and
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is byte addressable. 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 big endian
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fashion by the processors in this family.
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Some of the XXX family members such as the
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XXX, XXX, and XXX support virtual memory and
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segmentation. The XXX requires external hardware support
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such as the XXX Paged Memory Management Unit coprocessor
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which is typically used to perform address translations for
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these systems. RTEMS does not support virtual memory or
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segmentation on any of the XXX family members.
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