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Date:      Sun, 30 Jun 2002 14:17:21 -0700 (PDT)
From:      Julian Elischer <julian@elischer.org>
To:        Charles Sprickman <freebsd@fasttrackmonkey.com>
Cc:        "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>
Subject:   Re: getting a coredump before boot device found
Message-ID:  <Pine.BSF.4.21.0206301405490.86477-100000@InterJet.elischer.org>
In-Reply-To: <Pine.OSX.4.44.0206301642310.1343-100000@white.nat.fasttrackmonkey.com>

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On Sun, 30 Jun 2002, Charles Sprickman wrote:

> On Sun, 30 Jun 2002, Julian Elischer wrote:
> 
> > at that stage  abut all you can do is live debugging..
> 
> Meaning boot kernel.debug directlly so I've got a kernel with symbols and
> then get out the pen and paper?
> 
> > do you have 2 machines you can link together?
> 
> Oh yes.  But I know nothing about remote gdb.

it's not that difficult..

have the source and compile directory on the 2nd machine so gdb can access
it. compile with debug symbols (config -g). Have the following .gdbinit in
the compile/MYKENEL directory:

file kernel.debug
set remotebaud 9600
target remote  /dev/cuaa1

then connect a null modem cable getween com2 of both machines.
on the booting machine you need 'flags 0xc0 on sio1' in the config
or from the kernel configurator when you boot.
to tell the gdb stub that is where to go.

when it crashes into the ddb
type 'tr' 
to get a good backtrace,
then type 'gdb' to set gdb mode
then 's' to switch to it.

on the compile machine, in the compile/MYKERN directory,
type 'gdb'
(you must have compiled with debug support.... "config -g")

to go back to ddb

'det'

to reboot from ddb:

call boot 0
 (you may need to do it more than once).

> 
> Charles
> 
> >
> > On Sun, 30 Jun 2002, Charles Sprickman wrote:
> >
> > > Hi,
> > >
> > > I'm wondering if there's any way to get a coredump on a machine that's
> > > panicing while probing ata-attached drives.  I'd like to help someone fix
> > > whatever this remaining ata bug is in 4.6 and -stable, but I'm stumped on
> > > how to do this.  I can break into the debugger, but my only option there
> > > to write a core is to "panic" again, but since there's no dump device
> > > configured yet...  chicken and egg...
> > >
> > > Is this at all possible?  I couldn't find anything in the DDB manpage, nor
> > > in a quick google search.
> > >
> > > Thanks,
> > >
> > > CS
> > >
> > >
> > > To Unsubscribe: send mail to majordomo@FreeBSD.org
> > > with "unsubscribe freebsd-hackers" in the body of the message
> > >
> >
> >
> 
> 


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