How to get back from "testing" to "stable" - Kernel downgrade

Question

currently I am having lot's of fun with apt-get - and the bad thing is, it was my own fault. I had enabled the testing packages in /etc/apt/sources.list to install a certain package. And I told my system do apt-get dist-upgrade. Everything worked fine, but now I am trying to get back to the stableupdated - and I fail...

When trying to do the apt-get dist-upgrade, i get the following information:

The following packages will be REMOVED:
  linux-image-3.10-3-amd64
The following NEW packages will be installed:
  libcgi-fast-perl libfcgi-perl libyaml-syck-perl
The following packages will be DOWNGRADED:
  initramfs-tools libdate-manip-perl munin munin-common

Well, that's okay, but when I am try to do this, I get a warning in bold friendly red letters:

You are running a kernel (version 3.10-3-amd64) and attempting to remove the same version.
...
It is highly recommended to abort the kernel removal unless you are prepared to fix the system after removal.

Well, I like to follow the recommendmend. The correct kernel version for the stable release would be linux-image-3.2.0-4-amd64 and it is already installed. Probably the downgrade would be no problem if I was working under the older kernel? Actually, I have no clue how to enable the kernel 3.2.0 instead of 3.10.

Answer 1

Look at this, it seems to indicate that downgrade is possible using apt-get:

http://ispire.me/downgrade-from-debian-sid-to-stable-from-jessie-to-wheezy/

Essentials (3-step):
(If much of your system is of a higher version, you'll want to be careful downgrading. See especially format changes (data and personal config files)

1. Remove all references to sid or unstable in your /etc/apt/sources.list by deleting, replacing, or commenting out. Ensure sources.list has what you do want (I recommend security and stable deb sources). For example:

   deb http://security.debian.org/ wheezy/updates main
   deb-src http://security.debian.org/ wheezy/updates main

   deb http://cdn.debian.net/debian/ wheezy main contrib non-free
   deb-src http://cdn.debian.net/debian/ wheezy main contrib non-free

2. Pin the release you want in /etc/apt/preferences (this will cause the already downloaded but now unwanted package information to be ignored as desired).

   Package: *
   Pin: release a=stable
   Pin-Priority: 1001

3. Finally we have to run the apt update and upgrade process for downgrading all packages.
   *apt will ask for confirmation

   # apt-get update
# apt-get upgrade
# apt-get dist-upgrade

If you can't explain what each of these commands does independently, read your man pages! :) And do the same for at least the options you use in other utilities.

4. (If you have issues downgrading a package) Purge it, then reinstall

   # apt-get purge [your_failing_package]
# apt-get install [your_failing_package]

Answer 2

• Reboot the machine.
• From Debian advanced menu on Grub, choose a kernel different from the one you want to remove.

• If you're on Debian you'd have a meta package for the kernel installed.

  gayan@deb:~$ dpkg -l | grep linux 
  ii  linux-image-amd64                     4.9.25-1~bpo8+1
  ii  linux-image-3.16.0-4-amd64            3.16.43-2
  ii  linux-image-4.9.0-0.bpo.3-amd64       4.9.25-1~bpo8+1
  

• Simply purge the meta package (linux-image-amd64) and and reinstall it.

  Then you'd have:

  gayan@deb:~$ dpkg -l | grep linux
  ii  linux-image-amd64                     3.16.43-2
  ii  linux-image-3.16.0-4-amd64            3.16.43-2
  

• Reboot.

---

Info:

linux-image-amd64 is a meta package. It could point to a either stable kernel or a back-ported one (4.9.25-1~bpo8+1) depending on how you install it:

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

or

apt-get install linux-image-amd64