Date: Mon, 30 Aug 1999 14:47:03 -0400 (EDT) From: Zhihui Zhang <zzhang@cs.binghamton.edu> To: freebsd-hackers@FreeBSD.ORG Subject: Re: Help with remote debugging (gdb -k) Message-ID: <Pine.GSO.3.96.990830144356.10304F-100000@sol.cs.binghamton.edu> In-Reply-To: <Pine.GSO.3.96.990830142223.10304D-100000@sol.cs.binghamton.edu>
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On Mon, 30 Aug 1999, Zhihui Zhang wrote:
>
> After reading the handbook and some postings in the mailing list archive.
> I still can not make remote debugging work. I basically did the following
> on FreeBSD-current 4.0 (A is debugging machine, B is the target):
>
> (1) Build a debug kernel (options DDB and BREAK_TO_DEBUGGER) on box A.
> The sio flag I used is 0x90 (I also tried 0x80). Ftp the file /kernel to
> box B and renamed as /kernel.A
>
> (2) Boot the kernel /kernel.A on box B with -d option:
>
> >>FreeBSD/i386 boot
> Default: 0:wd(0,a)/boot/loader
> boot: /kernel.A -d
> Debugger("Boot flags requested debugger")
> Stopped at 0xc0252c27: movl $0, 0xc031ed98
> db> gdb
> Next trap will enter GDB remote protocol mode
> db> s
>
> (3) On machine A, go to the compile directory:
>
> #gdb -g kernel.debug
>
> (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
>
> The serial cable is null-modem and has been tested with kermit. It is
> connected to /dev/ttyd0 (com 1) of machine B and com 2 of machine A.
>
> I did not do "strip -x" because I assume this is done by FreeBSD 4.0
> automatically and the file debug.kernel is the one with symbols.
>
> Any help is appreciated.
>
I have just found the reason. I should specify the local serial port of
the debugging machine. So I should use:
(kgdb) target remote /dev/cuaa1 <-- do not use /dev/cuaa0
Now everything works fine.
-Zhihui
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