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I got a vServer with Debian installed (important because I have no idea of how Debian was installed and/or built). Output of ~# uname -r: 2.6.26-2-xen-amd64.

After execution of (first some other version 3.2 kernel installations and then) ~# apt-get install xen-linux-system-3.2.0-4-amd64 and preceding ~# update-grub and ~# reboot the kernel version seems to be unchanged. Why?

~# dpkg -l | grep xen gives (reformatted):

libxen-4.1 (4.1.4-2)
libxenstore3.0 (4.1.4-2)
xen-hypervisor-4.1-amd64 (4.1.4-2)
xen-linux-system-3.2.0-4-amd64 (3.2.35-2)
xen-system-amd64 (4.1.4-2)
xen-utils-4.1 (4.1.4-2)
xen-utils-common (4.1.4-2)
xenstore-utils (4.1.4-2)

~# cat /boot/grub/grub.cfg gives:

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
  load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}

function load_video {
  insmod vbe
  insmod vga
  insmod video_bochs
  insmod video_cirrus
}

insmod ext2
set root='(/dev/hda1)'
search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
if loadfont /usr/share/grub/unicode.pf2 ; then
  set gfxmode=640x480
  load_video
  insmod gfxterm
  insmod ext2
  set root='(/dev/hda1)'
  search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
  set locale_dir=($root)/boot/grub/locale
  set lang=de_DE@euro
  insmod gettext
fi
terminal_output gfxterm
set timeout=5
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=cyan/blue
set menu_color_highlight=white/blue
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Debian GNU/Linux, mit Linux 3.2.0-4-amd64' --class debian --class gnu-linux --class gnu --class os {
    load_video
    insmod gzio
    insmod ext2
    set root='(/dev/hda1)'
    search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
    echo    'Linux 3.2.0-4-amd64 wird geladen ...'
    linux   /boot/vmlinuz-3.2.0-4-amd64 root=UUID=5c2c9779-894e-4dfc-9707-9fecdbc085c5 ro  quiet
    echo    'Initiale Ramdisk wird geladen ...'
    initrd  /boot/initrd.img-3.2.0-4-amd64
}
menuentry 'Debian GNU/Linux, mit Linux 3.2.0-4-amd64 (Wiederherstellungsmodus)' --class debian --class gnu-linux --class gnu --class os {
    load_video
    insmod gzio
    insmod ext2
    set root='(/dev/hda1)'
    search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
    echo    'Linux 3.2.0-4-amd64 wird geladen ...'
    linux   /boot/vmlinuz-3.2.0-4-amd64 root=UUID=5c2c9779-894e-4dfc-9707-9fecdbc085c5 ro single 
    echo    'Initiale Ramdisk wird geladen ...'
    initrd  /boot/initrd.img-3.2.0-4-amd64
}
menuentry 'Debian GNU/Linux, mit Linux 3.2.0-0.bpo.4-amd64' --class debian --class gnu-linux --class gnu --class os {
    load_video
    insmod gzio
    insmod ext2
    set root='(/dev/hda1)'
    search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
    echo    'Linux 3.2.0-0.bpo.4-amd64 wird geladen ...'
    linux   /boot/vmlinuz-3.2.0-0.bpo.4-amd64 root=UUID=5c2c9779-894e-4dfc-9707-9fecdbc085c5 ro  quiet
    echo    'Initiale Ramdisk wird geladen ...'
    initrd  /boot/initrd.img-3.2.0-0.bpo.4-amd64
}
menuentry 'Debian GNU/Linux, mit Linux 3.2.0-0.bpo.4-amd64 (Wiederherstellungsmodus)' --class debian --class gnu-linux --class gnu --class os {
    load_video
    insmod gzio
    insmod ext2
    set root='(/dev/hda1)'
    search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
    echo    'Linux 3.2.0-0.bpo.4-amd64 wird geladen ...'
    linux   /boot/vmlinuz-3.2.0-0.bpo.4-amd64 root=UUID=5c2c9779-894e-4dfc-9707-9fecdbc085c5 ro single 
    echo    'Initiale Ramdisk wird geladen ...'
    initrd  /boot/initrd.img-3.2.0-0.bpo.4-amd64
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
submenu "Xen 4.1-amd64" {
menuentry 'Debian GNU/Linux, mit Xen 4.1-amd64 und Linux 3.2.0-4-amd64' --class debian --class gnu-linux --class gnu --class os --class xen {
    insmod ext2
    set root='(/dev/hda1)'
    search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
    echo    'Xen 4.1-amd64 wird geladen ...'
    multiboot   /boot/xen-4.1-amd64.gz placeholder  
    echo    'Linux 3.2.0-4-amd64 wird geladen ...'
    module  /boot/vmlinuz-3.2.0-4-amd64 placeholder root=UUID=5c2c9779-894e-4dfc-9707-9fecdbc085c5 ro  quiet
    echo    'Initiale Ramdisk wird geladen ...'
    module  /boot/initrd.img-3.2.0-4-amd64
}
menuentry 'Debian GNU/Linux, mit Xen 4.1-amd64 und Linux 3.2.0-4-amd64 (Wiederherstellungsmodus)' --class debian --class gnu-linux --class gnu --class os --class xen {
    insmod ext2
    set root='(/dev/hda1)'
    search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
    echo    'Xen 4.1-amd64 wird geladen ...'
    multiboot   /boot/xen-4.1-amd64.gz placeholder 
    echo    'Linux 3.2.0-4-amd64 wird geladen ...'
    module  /boot/vmlinuz-3.2.0-4-amd64 placeholder root=UUID=5c2c9779-894e-4dfc-9707-9fecdbc085c5 ro single 
    echo    'Initiale Ramdisk wird geladen ...'
    module  /boot/initrd.img-3.2.0-4-amd64
}
menuentry 'Debian GNU/Linux, mit Xen 4.1-amd64 und Linux 3.2.0-0.bpo.4-amd64' --class debian --class gnu-linux --class gnu --class os --class xen {
    insmod ext2
    set root='(/dev/hda1)'
    search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
    echo    'Xen 4.1-amd64 wird geladen ...'
    multiboot   /boot/xen-4.1-amd64.gz placeholder  
    echo    'Linux 3.2.0-0.bpo.4-amd64 wird geladen ...'
    module  /boot/vmlinuz-3.2.0-0.bpo.4-amd64 placeholder root=UUID=5c2c9779-894e-4dfc-9707-9fecdbc085c5 ro  quiet
    echo    'Initiale Ramdisk wird geladen ...'
    module  /boot/initrd.img-3.2.0-0.bpo.4-amd64
}
menuentry 'Debian GNU/Linux, mit Xen 4.1-amd64 und Linux 3.2.0-0.bpo.4-amd64 (Wiederherstellungsmodus)' --class debian --class gnu-linux --class gnu --class os --class xen {
    insmod ext2
    set root='(/dev/hda1)'
    search --no-floppy --fs-uuid --set=root 5c2c9779-894e-4dfc-9707-9fecdbc085c5
    echo    'Xen 4.1-amd64 wird geladen ...'
    multiboot   /boot/xen-4.1-amd64.gz placeholder 
    echo    'Linux 3.2.0-0.bpo.4-amd64 wird geladen ...'
    module  /boot/vmlinuz-3.2.0-0.bpo.4-amd64 placeholder root=UUID=5c2c9779-894e-4dfc-9707-9fecdbc085c5 ro single 
    echo    'Initiale Ramdisk wird geladen ...'
    module  /boot/initrd.img-3.2.0-0.bpo.4-amd64
}
}
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f  $prefix/custom.cfg ]; then
  source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
share|improve this question
    
What is the nature of the VM host? Are you in control of that? Are you sure that it is set up to allow guests to choose their own kernel? –  EEAA Mar 9 '13 at 21:16
    
@EEAA Nope, as I said, no idea how it is set up. I didn't know it is possible to restrict it to one kernel... maybe I should ask the vServer providers support :/ –  Matmarbon Mar 9 '13 at 21:18
1  
Yes you should. There's a chance you may need to use pv-grub. –  EEAA Mar 9 '13 at 21:22
1  
The Kernel can be configured in the configuration file of the VM (caled domU in XEN) if PV is used. Grub does not load in this case. –  Tim Haegele Mar 9 '13 at 21:23

2 Answers 2

up vote 1 down vote accepted

In accord with EEAA's and Tim Haegele's comments (not answers so they can't get reputation for it, sorry), it was the VM host which was configured for a specific kernel version. Sadly I could not get my provider to change that, now I had instead to downgrade my Debian from Sid to Lenny (which is not possible and led to restoring the backup) but that is another story.

share|improve this answer

You need to run the following to set Xen kernel to be of a higher priority than your current kernel:

dpkg-divert --divert /etc/grub.d/08_linux_xen --rename /etc/grub.d/20_linux_xen
update-grub
share|improve this answer
    
Maybe good to know for anyone else but you straight beg the question. –  Matmarbon Mar 13 '13 at 19:04

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