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Network Debugging Protocol (RFC0643)

IP.com Disclosure Number: IPCOM000003714D
Original Publication Date: 1974-Jul-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 7 page(s) / 13K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

E. Mader: AUTHOR

Abstract

The protocol is a level 2 protocol, which bypasses the ARPANET HOST-HOST protocol. (This is implemented on TENEX using special privileged system calls which allow messages to be sent directly to and received directly from the IMP). Messages are sent between the PDP-11 and the remote debugger on one link (currently 377 octal). Each message from the remote debugger to the PDP-ll is a request that the PDP-11 perform some action, and each message from the PDP-11 to the remote debugger is either a reply to that request or an indication that a process has stopped running (i.e. has trapped, hit a breakpoint, etc). The exact format of the messages is shown in Figure 1 below.

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 22% of the total text.

Network Debugging Protocol Eric Mader

RFC: 643 July 1974

NIC #30873

This document describes a proposed protocol to be used in an

implementation of a PDP-11 network Bootstrap service and a

cross-network debugger. The protocol is designed for debugging

processes running under an operating system which can perform some of

the "lower level" debugging tasks, such as planting and removing

breakpoints and single stepping. A subset of the protocol could be

used if such a capability does not exist (a stand-alone program for

example).

The protocol is a level 2 protocol, which bypasses the ARPANET

HOST-HOST protocol. (This is implemented on TENEX using special

privileged system calls which allow messages to be sent directly to

and received directly from the IMP). Messages are sent between the

PDP-11 and the remote debugger on one link (currently 377 octal).

Each message from the remote debugger to the PDP-ll is a request that

the PDP-11 perform some action, and each message from the PDP-11 to

the remote debugger is either a reply to that request or an indication

that a process has stopped running (i.e. has trapped, hit a

breakpoint, etc). The exact format of the messages is shown in Figure

1 below.

Each command consists of an 8-bit op-code, and an 8-bit

process-id, two 16-bit arguments, and an optional string of 8-bit

bytes. The op-code field from the PDP-11 should be the same as that

sent by the remote host to indicate successful completion of the

request or be the same as that set by the remote host with the 200 bit

set to indicate failure to complete the request. Op-codes from the

PDP-11 which have the 100 bit set are asynchronous indication that a

process has stopped for a reason other than a request from the remote

host. (See description of asynchronous replies below). An op-code

from the PDP-11 with both the 100 and 200 bit set is meaningless.

Thus, the 8-bit op-code field sent by the PDP-11 can be thought of as

a CAN'T Flag, an Asynchronous STOP Flag, and a 6-bit op-code.

In the description that follows the commands will be given as

NAME (Process-ID, Argument 1, Argument 2, BYTE STRING)

with only as many of the fields present as are used.

Op-Code 0 - NOP_______ _ _ ___

This command is intended to be used to determine if the PDP-11 is

operational. It has no effect on any process running in the PDP-11.

The response is NOP.

Op-Code 1 - DEBUG (Process)_______ _ _ _____ _________

This command requests the ability to debug the given process.

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