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Date:      Tue, 10 May 2011 17:17:51 +0000
From:      dhaneshk k <dhaneshkk@hotmail.com>
To:        <questions@freebsd.org>
Subject:   kgdb  and   vmcore.0   cannot access memory at 0x252d1
Message-ID:  <BLU154-w43AD9D9364EAC46944A849B2870@phx.gbl>

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list=2C

 I  am new to kernel debugging=2C   I compiled  a new  kernel with     opti=
ons   KDB and DDB    in addition to the GENERIC config and booted with the =
new  kernel.( Goal is to debug  the coredumps  in my laptops /var/crash/vmc=
ore  files and try to find and fix the panic/situation which produce these =
coredumps)

I tried to analyze   all  of the   vmcore files    in my /var/crash/vmcore.=
x    core dumps

steps done
after booting  into the   new kernel

#  cd /usr/obj/usr/src/sys/MYCUSTORMKERNEL
#kgdb kernel.debug  /var/crash/vmcore.0

 kgdb kernel.debug /var/crash/vmcore.0
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation=2C Inc.
GDB is free software=2C covered by the GNU General Public License=2C and yo=
u are
welcome to change it and/or distribute copies of it under certain condition=
s.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-marcel-freebsd"...
Cannot access memory at address 0x252d1
(kgdb)=20
(kgdb)=20

For all the vmcore files  I am getting  this output..      Cannot access me=
mory at address 0x252d1=2C     how can I proceed  from here=2C=20

How to debug  what  is happening=2C  what makes the kernel  to dump these v=
mcores  and  fix the issue by using  further debugging..
what  are the next steps =2C  if there a message  in kgdb  "Cannot access m=
emory at address   0x252d1 or any address" =20

Please share your  suggestion and hints to debug  more from this point. I a=
m stuck here..

Thanks in advance
Dhanesh



 		 	   		  =



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