Adaptec 2940U - AHA Storage Controller Ultra SCSI 20 MBps Informacje Techniczne Pobierz pdf (Strona 169)

Chapter 7 Troubleshooting the System 155

readable manner; for example, displaying regions of memory in terms of their

actual usage instead of as lists of hexadecimal numbers. For the information

presented to be meaningful, it is important that the symbols present on the target

and host computers be identical.

The host computer controls the target computer through a serial communications

port. The host can be connected to a local target computer by a serial

communications null-modem cable (local debugging), or the host can be at a

remote location (such as Citrix headquarters) and connected to the target computer

by modem (remote debugging). The modem used can be any standard Hayes-

compatible PC modem; however, Citrix recommends using a U.S. Robotics

Sportster series 56Kbps modem for best results.

This section describes how to configure a target computer and a host computer for

local or remote debugging.

The Kernel Debugger (I386kd.exe)

Using the kernel debugger program, I386kd.exe, a support engineer can use the

host computer to control program execution on the target computer. The target

computer can be allowed to run until an error condition occurs or it can be

manually stopped at any time. The action of stopping the target computer is called

breaking in. The support engineer breaks into the target computer by pressing

CTRL+C in the kernel debugger session on the host computer. If a trap or fault

occurs on the target computer, the target machine halts and displays system

information. At this point, the operator on the host computer can interactively

examine the status of the target computer or allow execution to resume. Press G in

the kernel debugger session on the host computer to allow execution on the target

computer to resume.

The kernel debugger can be used to set execution and memory access breakpoints,

examine and modify memory contents, check the state of CPU registers,

disassemble code, and other operations.

Symbols and Symbol Trees

To allow symbolic debugging (that is, debugging using descriptive text instead of

hex numbers), symbols are loaded onto both the target and host computers. These

symbols contain information used to present data to technical personnel in a more

readable manner; for example, displaying regions of memory in terms of their

actual usage instead of as lists of hexadecimal numbers.

For the information presented to be meaningful, it is important that the symbols

installed on the target and host computers be identical and that they match the

executable files on the target computer. The symbol files for the base MetaFrame

system are located on the MetaFrame CD-ROM in the \Support\Debug\I386

\Symbols directory. The Symbols directory contains directories corresponding to

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Adaptec 2940U - AHA Storage Controller Ultra SCSI 20 MBps Informacje Techniczne Strona 169