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diff --git a/cpu_supplement/preface.rst b/cpu_supplement/preface.rst index d47b9e3..0fa6341 100644 --- a/cpu_supplement/preface.rst +++ b/cpu_supplement/preface.rst @@ -1,56 +1,46 @@ .. comment SPDX-License-Identifier: CC-BY-SA-4.0 -======= -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. +======= +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. |