Date: Tue, 22 Dec 1998 12:41:22 +1030 From: Greg Lehey <grog@lemis.com> To: Sheldon Hearn <axl@iafrica.com>, freebsd-questions@FreeBSD.ORG Subject: Re: Remote kernel debugging over serial Message-ID: <19981222124122.Q85005@freebie.lemis.com> In-Reply-To: <4684.914270675@axl.noc.iafrica.com>; from Sheldon Hearn on Mon, Dec 21, 1998 at 10:04:35PM %2B0200 References: <4684.914270675@axl.noc.iafrica.com>
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On Monday, 21 December 1998 at 22:04:35 +0200, Sheldon Hearn wrote: > > Hi folks, > > I'm trying to use the instructions in Chapter 22.4 of the handbook to > debug a problem I have using teh ATAPI CD-ROM driver in 2.2-STABLE. > > I think I've followed the instructions in the handbook to the letter, > but am having a bit of a problem trying to get gdb to talk to the > debugging kernel on the target host. I'm using a null modem cable on > serial0 of each box (/dev/cuaa0). The cable itself has been tested by a > friend using Wintendo games that called for "a null modem cable". I > assume there's only one workable wiring standard for such a thing. This is a bad assumption. There are all sorts of cables that could possibly be called ``null modem''. > This is the error I get: > >> [root@axl] /usr/src/sys/compile/GDB # gdb -k kernel >> GDB is free software and you are welcome to distribute copies of it >> under certain conditions; type "show copying" to see the conditions. >> There is absolutely no warranty for GDB; type "show warranty" for >> details. >> GDB 4.16 (i386-unknown-freebsd), >> Copyright 1996 Free Software Foundation, Inc... >> (kgdb) target remote /dev/cuaa0 >> Remote debugging using /dev/cuaa0 >> Ignoring packet error, continuing... >> Ignoring packet error, continuing... >> Couldn't establish connection to remote target >> Malformed response to offset query, timeout >> (kgdb) This is a pretty general message saying ``no connection''. You don't say what you were doing at the other end. Initially you need to get the other machine to go into ddb, for example by pressing ctrl-alt-esc, entering the command ``gdb'', and then single-stepping. If you don't do this, you will always get the messages you describe, whether or not you have a cable connected. If you're doing all this, it might be worth having a breakout box connected to see what's really going on. Looking at the cable I have connected on my setup, the debugged machine asserts RTS and DTR, the gdb machine asserts DCD and DSR and echos CTS for RTS. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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