linux-kernel - Re: kexec / kdump kernel panic

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Date:	Wed, 4 Oct 2006 14:38:53 -0700
From:	"Steven Truong" <midair77@...il.com>
To:	"Valdis.Kletnieks@...edu" <Valdis.Kletnieks@...edu>,
	linux-kernel@...r.kernel.org
Subject: Re: kexec / kdump kernel panic

Hi, Valdis.  No, I actually used 2 different kernels for this:  one
for system kernel and the other for captured/crash kernel.

System kernel .config file with these options

CONFIG_KEXEC=y
CONFIG_CRASH_DUMP=y
CONFIG_PHYSICAL_START=0x1000000
CONFIG_SYSFS=y
CONFIG_DEBUG_INFO=y

make; make modules_install; make install

System kernel Grub entry

title CentOS (2.6.18)
      root (hd0,0)
      kernel /vmlinuz-2.6.18 ro root=/dev/sda3 crashkernel=128M@16M rhgb quiet
      initrd /initrd-2.6.18.img


Crash/captured kernel .config file with these options
CONFIG_LOCALVERSION="-kdump"
# CONFIG_SMP is not set
CONFIG_KEXEC=y    <-------------------------------------------------------------
CONFIG_CRASH_DUMP=y
CONFIG_PHYSICAL_START=0x1000000
CONFIG_PROC_VMCORE=y

the /boot/vmlinux is found in the linux-2.6.18kdump directory after I
make and make install_modules for the crash kernel.

Am I missing something? Or did I do something wrong?  Is my vmlinux ok
or how I go about to obtain an uncompressed ELF image of the crash
kernel?

Thank you for all the helps.
Steven.

On 10/3/06, Valdis.Kletnieks@...edu <Valdis.Kletnieks@...edu> wrote:
> On Tue, 03 Oct 2006 17:18:21 PDT, Steven Truong said:
>
> > /usr/sbin/kexec -p /boot/vmlinux
> > --initrd=/boot/initrd-2.6.18-kdump.img --args-linux
> > --append="root=/dev/sda3  irqpoll init 1"
>
> If the /boot/vmlinux is the one you usually use to boot, that won't work.
>
> Your usual vmlinux is almost certainly linked to load at the 1M line,
> and you need a kernel linked to load at the 16M line (as set in crashkernel=).
>
> See the CONFIG_PHYSICAL_START config option, and there's other details
> in Documentation/kdump/kdump.txt - it looks like you have most of it right,
> except you need to build *TWO* specially configured kernels (your production
> one with KEXEC support and a few other things, and then the dump kernel
> with a different PHYSICAL_START and a few settings).
>
>
>
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