mirror of
https://git.rtems.org/rtems-docs/
synced 2025-06-03 09:19:30 +08:00
55 lines
2.2 KiB
ReStructuredText
55 lines
2.2 KiB
ReStructuredText
=======
|
|
Preface
|
|
=======
|
|
|
|
|
|
The Real Time Executive for Multiprocessor Systems
|
|
(RTEMS) is designed to be portable across multiple processor
|
|
architectures. However, the nature of real-time systems makes
|
|
it essential that the application designer understand certain
|
|
processor dependent implementation details. These processor
|
|
dependencies include calling convention, board support package
|
|
issues, interrupt processing, exact RTEMS memory requirements,
|
|
performance data, header files, and the assembly language
|
|
interface to the executive.
|
|
|
|
Each architecture represents a CPU family and usually there are
|
|
a wide variety of CPU models within it. These models share a
|
|
common Instruction Set Architecture (ISA) which often varies
|
|
based upon some well-defined rules. There are often
|
|
multiple implementations of the ISA and these may be from
|
|
one or multiple vendors.
|
|
|
|
On top of variations in the ISA, there may also be variations
|
|
which occur when a CPU core implementation is combined with
|
|
a set of peripherals to form a system on chip. For example,
|
|
there are many ARM CPU models from numerous semiconductor
|
|
vendors and a wide variety of peripherals. But at the
|
|
ISA level, they share a common compatibility.
|
|
|
|
RTEMS depends upon this core similarity across the CPU models
|
|
and leverages that to minimize the source code that is specific
|
|
to any particular CPU core implementation or CPU model.
|
|
|
|
This manual is separate and distinct from the RTEMS Porting
|
|
Guide. That manual is a guide on porting RTEMS to a new
|
|
architecture. This manual is focused on the more mundane
|
|
CPU architecture specific issues that may impact
|
|
application development. For example, if you need to write
|
|
a subroutine in assembly language, it is critical to understand
|
|
the calling conventions for the target architecture.
|
|
|
|
The first chapter in this manual describes these issues
|
|
in general terms. In a sense, it is posing the questions
|
|
one should be aware may need to be answered and understood
|
|
when porting an RTEMS application to a new architecture.
|
|
Each subsequent chapter gives the answers to those questions
|
|
for a particular CPU architecture.
|
|
|
|
.. COMMENT: COPYRIGHT (c) 1988-2002.
|
|
|
|
.. COMMENT: On-Line Applications Research Corporation (OAR).
|
|
|
|
.. COMMENT: All rights reserved.
|
|
|