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From: John Baldwin <jhb@freebsd.org>
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Date: Fri, 15 Jun 2012 08:21:37 -0400
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	(bigwig.baldwin.cx); Fri, 15 Jun 2012 13:18:25 -0400 (EDT)
Cc: nagarjuna vempati <nagpersonal@gmail.com>
Subject: Re: Issue with KGDB setup. System freezes when it enters ddb
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On Monday, June 11, 2012 12:49:46 pm nagarjuna vempati wrote:
> Hello,
> 
> Can someone plese help me understand what is the problem?
> 
> After fresh disk installation of freeBSD9.0 AMD64 from disk, I copied
> /usr/src/sys/am64/conf/GENERIC to KGDBKERNEL and added following lines to
> the file
> 
> options         GDB
> options         DDB
> options         KDB_UNATTENDED
> options         BREAK_TO_DEBUGGER
> options         ALT_BREAK_TO_DEBUGGER
> 
> After this I rebuilt the Kernel and installed as below.
> 
> make buildworld
> make buildkernel kernconf=KGDBKERNEL
> make installkernel kernconf=KGDBKERNEL
> Reboot into single user mode.
> mergemaster -p
> make installworld
> mergemaster
> Reboot.
> 
> After this to setup KGDB I am using following document as my reference.
> http://chetanbl.blogspot.com/
> 
> 
> To break into ddb I am trying issue sysctl debug.kdb.enter=1. Then the
> system becomes unresponsive. Also, I tried to enter ddb at booting stage by
> issuing boot -d command. Even then system becomes unresponsive.
> 
> I need to solve this problem ASAP. Can someone helpme?

The first thing I would try is to see if you can just get into DDB.  Note that 
DDB is going to use your primary console, so if you haven't setup a serial 
console for your machine, then the DDB prompt will be on the VGA console.

-- 
John Baldwin