CISCO IE-4000-16GT4G-E工业交换机,用户手册
保持调试器运行环境
本节介绍了如何避免污染操作系统调试器的环境。涵盖的主题包括：
❏ 187Bug向量表和工作空间❏ 硬件功能
❏ 187Bug使用的异常向量❏ CPU/MPU寄存器
187Bug使用某些MVME187板载资源，并且可能也可以使用非车载系统内存来包含临时变量，异常向量，等等，如果你干扰了你所依赖的资源则调试器的功能可能不可靠或根本不起作用。
CISCO IE-4000-16GT4G-E工业交换机如果应用程序允许通过内存进行翻译管理单元（MMU），并利用调试器的资源（例如，系统调用），应用程序必须创建必要的调试器访问其各种资源。调试器支持MMU的启用；确实如此不禁用翻译。187Bug向量表和工作空间调试器和诊断固件位于EPROM中。这个调试器还使用前64KB的RAM存储向量表、可执行代码、变量和堆栈。硬件功能调试器使用的唯一硬件资源是EIA232-D端口，这些端口初始化为与调试终端接口还有一个主持人。如果对这些端口重新编程，则终端必须修改特性以适应，否则端口应在重新调用之前还原到调试器集特征调试器。
注意，尽管187Bug没有明确管理MC88200或MC88204 CMMU，硬件防止在MVME187上缓存输入/输出空间，即。，$FFFXXXXX。此外，代码缓存不得可用于正在跟踪的代码页或已中断。187Bug使用的异常向量前16个MC88100异常向量（即#496到511）保留供调试器使用。
Preserving the Debugger Operating
Environment
This section explains how to avoid contaminating the operating
environment of the debugger. Topics covered include:
❏ 187Bug Vector Table and workspace
❏ Hardware functions
❏ Exception vectors used by 187Bug
❏ CPU/MPU registers
187Bug uses certain of the MVME187 onboard resources and may
also use offboard system memory to contain temporary variables,
exception vectors, etc. If you disturb resources upon which 187Bug
depends, then the debugger may function unreliably or not at all.
If your application enables translation through the Memory
Management Units (MMUs), and utilizes resources of the debugger
(e.g., system calls), your application must create the necessary
translation tables for the debugger to have access to its various
resources. The debugger honors the enabling of the MMUs; it does
not disable translation.
187Bug Vector Table and Workspace
The debugger and diagnostic firmware resides in the EPROMs. The
first 64KB of RAM are also used by the debugger for storage of the
Vector Table, executable code, variables, and stack. Hardware Functions
The only hardware resources used by the debugger are the EIA232-D ports, which are initialized to interface to the debug terminal
and a host. If these ports are reprogrammed, the terminal
characteristics must be modified to suit, or the ports should be
restored to the debugger-set characteristics prior to reinvoking the
debugger.
Note Although the 187Bug does not explicitly manage the
MC88200 or MC88204 CMMUs, hardware prevents
caching of I/O space on the MVME187, i.e.,
$FFFXXXXX. Furthermore, the code cache must not be
operative for code pages which are being traced or
breakpointed.
Exception Vectors Used by 187Bug
The top 16 MC88100 exception vectors (i.e., #496 to 511 inclusive)
are reserved for use by the debugger
