I have a RHEL6.0 server (kernel 2.6.32-37.el6.i686) installed on VMware. I wanted to learn how to updated kernel, so I downloaded kernel 2.6.32.62 package from https://www.kernel.org to /root/Desktop and run the following command respectively:

[root@RHEL6VM Desktop]# tar -xf linux-2.6.32.62.tar.xz
[root@RHEL6VM Desktop]# cd linux-2.6.32.62
[root@RHEL6VM linux-2.6.32.62]# make menuconfig
[root@RHEL6VM linux-2.6.32.62]# make dep
[root@RHEL6VM linux-2.6.32.62]# make clean
[root@RHEL6VM linux-2.6.32.62]# make bzImage
[root@RHEL6VM linux-2.6.32.62]# make modules
[root@RHEL6VM linux-2.6.32.62]# make modules_install
[root@RHEL6VM linux-2.6.32.62]# mv /boot/vmlinuz-2.6.32-37.el6.i686 /boot/vmlinuz-2.6.32-37.el6.i686.old
[root@RHEL6VM linux-2.6.32.62]# cp /root/Desktop/linux-2.6.32.62/arch/i386/boot/bzImage /boot/vmlinuz-2.6.32.62
[root@RHEL6VM linux-2.6.32.62]# Edited grub file and made changes as below
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/mapper/vg1_rhel6vm-LogVol001
# initrd /initrd-[generic-]version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux (2.6.32-37.el6.i686)
root (hd0,0)
kernel /vmlinuz-2.6.32-37.el6.i686 ro root=/dev/mapper/vg1_rhel6vm-LogVol001 rd_LVM_LV=vg1_rhel6vm/LogVol001 rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us crashkernel=auto rhgb quiet

title Red Hat Enterprise Linux (2.6.32.62)
root (hd0,0)
kernel /vmlinuz-2.6.32.62 ro root=/dev/mapper/vg1_rhel6vm-LogVol001 rd_LVM_LV=vg1_rhel6vm/LogVol001 rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us crashkernel=auto rhgb quiet
initrd /initramfs-2.6.32.62.img
[root@RHEL6VM linux-2.6.32.62]#

[root@RHEL6VM linux-2.6.32.62]# dracut -f initramfs-2.6.32.62.img 2.6.32.62

Now when I restarted my server, it was booting successfully with the new kernel (2.6.32.62) but when I tried to boot it from old kernel (2.6.32-37) it was giving the below error

Error 15: File not found
Press any key to continue...

I would appreciate if somebody can answer my following questions.

Q1: How to save changes made to grub file?
Q2: What can be the issue behind the error with the old kernel? and what is the solution?
Q3: Did I follow the correct procedure for updating the kernel?
Q4: How can I change the default kernel as it is still booting with the old kernel by default?

Just run:

Install first always the modules then the kernel image. Also in grub put the new kernel as first or change default to 1 or more depending on how many entries you got.

Hi Robert,

are you telling me that I should run the following commands in the listed sequence?

make menuconfig
make dep
make clean
make modules bzImage
make modules_install
make install

and how can I remove a particular kernel from the server?

The above command renamed the old kernel, did you change it back to the original (removing the .old from the end)? Your grub entry for the old kernel shows the original kernel line which would explain why you get the 'file not found' message.

Depending on how the kernel was installed. If it's an rpm package, then search for the name:

Otherwise, if it's manually installed, then:

Hi Yancek,

I removed the .old from vmlinuz file and renamed it to vmlinuz-2.6.32-37.el6.i686. However upon rebooting, I am getting the following error.

Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

You most probably didn't generate an initrd image or something didn't go as it should, but hard to tell.

Issue resolved!

Solution: initrd declaration was missing for the old kernel, added it and worked perfectly.