[CentOS] How to specify kernel version when restart kdump
Gianluca Cecchi
gianluca.cecchi at gmail.com
Thu Mar 28 08:24:56 UTC 2019
On Thu, Mar 28, 2019 at 6:55 AM wuzhouhui <wuzhouhui14 at mails.ucas.ac.cn>
wrote:
> > -----Original Messages-----
> > From: "Benjamin Hauger" <hauger at noao.edu>
> > Sent Time: 2019-03-28 01:31:40 (Thursday)
> > To: wuzhouhui <wuzhouhui14 at mails.ucas.ac.cn>, centos at centos.org
> > Cc:
> > Subject: Re: [CentOS] How to specify kernel version when restart kdump
> >
> > What do you mean? Wouldn't the kernel version always be the actual
> > running version of the kernel that was booted?
> >
> Suppose the running kernel is 2.6.32, and then I installed kernel 3.10.0.
> The files under /boot includes (exclude some unimportant files):
> initramfs-2.6.32.img
> initramfs-3.10.0.img
> vmlinuz-2.6.32
> vmlinuz-3.10.0
> initrd-2.6.32kdump.img
> We can see that there is no initrd-3.10.0kdump.img for newly installed
> kernel 3.10.0, and kdump will generate initrd-3.10.0kdump.img only when
> booted as kernel 3.10.0. However, I want kdump to generate
> initrd-3.10.0kdump.img
> now (the current running kernel is 2.6.32).
>
>
Your particolar versions seem quite strange because 2.6.32 lets me think
about CentOS 6 and 3.10.0 lets me think about CentOS 7.
Any way see below for some discussion, not tried by me, so in case please
use on test system before.
1) In CentOS 6 we have the classical SysV service
file: /etc/rc.d/init.d/kdump
Supposing you have just installed 2.6.32-642.13.1.el6.x86_64 kernel
Analyzing what it runs we have
DUMP_KERNELVER=""
MKDUMPRD_ARGS=""
. /etc/sysconfig/kdump
In my case:
KDUMP_BOOTDIR="/boot"
local running_kernel=`uname -r`
kdump_kver=`echo $running_kernel | sed 's/smp//g'`
MKDUMPRD="/sbin/mkdumprd -d -f $MKDUMPRD_ARGS"
kdump_initrd="${KDUMP_BOOTDIR}/initrd-${kdump_kver}kdump.img"
and at the end it runs this command if it doesn't find one:
$MKDUMPRD $kdump_initrd $kdump_kver
that tipically will translate in:
/sbin/mkdumprd -d -f "/boot/initrd-2.6.32-642.13.1.el6.x86_64kdump.img"
2) In CentOS 7 we have systemd unit files and for
kdump: /usr/lib/systemd/system/kdump.service
Supposing you have just installed 3.10.0-693.21.1.el7.x86_64
The script called actually it is /usr/bin/kdumpctl
See also fadump (firmware assisted dump) concepts in RHEL 7 / CentOS 7:
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/kernel_administration_guide/kernel_crash_dump_guide
But I think you are x86_64 so kdump sttill applies
In kdumpctl we have something like this:
MKDUMPRD="/sbin/mkdumprd -f"
TARGET_INITRD=""
. /lib/kdump/kdump-lib.sh
. /etc/sysconfig/kdump
eval $(cat /proc/cmdline| grep "BOOT_IMAGE" | cut -d' ' -f1)
KDUMP_BOOTDIR="/boot"$(dirname $BOOT_IMAGE)
kdump_kver=`uname -r`
TARGET_INITRD="${KDUMP_BOOTDIR}/initramfs-${kdump_kver}kdump.img"
rebuild_kdump_initrd()
{
$MKDUMPRD $TARGET_INITRD $kdump_kver
if [ $? != 0 ]; then
echo "mkdumprd: failed to make kdump initrd" >&2
return 1
fi
return 0
}
So at the end the command will be:
$MKDUMPRD $TARGET_INITRD $kdump_kver
that in general should be something like this if you want to compile for
kernel 3.10.0-693.21.1.el7.x86_64 :
/sbin/mkdumprd -f /boot/initramfs-3.10.0-693.21.1.el7.x86_64kdump.img
3.10.0-693.21.1.el7.x86_64
HIH trying,
Gianluca
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