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On Debian (Jessie) 8 I added the backports source and installed a newer kernel via:

apt-get update
apt-get install -t jessie-backports linux-image-amd64

I then ran

update-grub

However on reboot I do not see an option in GRUB to select the new kernel and the usual option loads the existing kernel:

uname -r
3.16.0-4-amd64

Firstly can I just update the kernel like this without recompiling all the software? (I want a new kernel in the hope it supports my hardware)

Second, if so, how do I make it appear in GRUB?

  • update-grub only updates the grub files that are used to build the grub configuration. You forgot to do grub-install, most common is grub-install /dev/sda. Make sure you are using kernel 4.7 from the backports. – Rui F Ribeiro Sep 21 '16 at 14:19
  • @RuiFRibeiro thanks - that put the entry in GRUB :) When I choose it I just get a black screen so it seems I haven't done the upgrade correctly (pressing power off does gracefully power off). – Kris Sep 22 '16 at 8:09
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    It was the graphics driver, if I booted with nomodeset (by pressing e on the Debian option and adding nomodeset in the end of the line starting linux) then I got a Desktop as expected. If you want to post your answer I will accept it. – Kris Sep 22 '16 at 9:02
  • all of this should be handeld automagicaly by the package manager (apt-get) ? I've never had to update grub manually when installing kernel from debian repository .... – Mali Sep 22 '16 at 11:13
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    @Mali I had to update grub because of my video card. Once I booted successfully in to the desktop for the first time all was well. I'm guessing the desktop was using the wrong videomode initially. – Kris Sep 23 '16 at 11:42
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Alas, expecting update-grub to work and create the grub boot-time tidbits is a common mistake I also made as a rookie.

update-grub only updates the grub files that are used to boot the grub configuration.

You have to do grub-install ; the most common of reinstalling/fixing grub is:

From Grub2/Installing - Post-Restoration Commands

To refresh the available devices and settings in /boot/grub/grub.cfg:

sudo update-grub

To look for the bootloader location.

grub-probe -t device /boot/grub

To install GRUB 2 to the sdX drive's MBR or boot sector (sda, sdb, etc.)

sudo grub-install /dev/sda

Since you are installing from the Debian backports, make sure you are using the latest kernel, which should be at the time of this post kernel 4.7.

  • 1
    grub-probe is a nice tip. – Kris Sep 22 '16 at 9:48

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