I occasionally update my kernel from this web site http://kernel.ubuntu.com/~kernel-ppa/mainline/

I have been always downloading 3 deb files for installing linux header all, linux image and linux headers. I noticed one more deb file recently for 64 bit kernel called Linux-image-extra.

I would like to know what does kernel file Linux-image-extra do and should I also install it?

up vote 43 down vote accepted

This answer is obsolete for modern Ubuntu releases

Without the extra package, most hardware won't work!

It contains extra drivers left out of the base kernel package; install it only if you need these drivers

Sometimes, a specific variant of the linux-image is slimmed down by removing the less common kernel modules (drivers). In this case, the linux-image-extra package simply contains all of the "extra" kernel modules which were left out.

  • Officially, this only happens for the -virtual image; the most common hypervisors (Virtualbox, VMWare, Xen, KVM) emulate a well-defined and restricted set of hardware, so removing unnecessary drivers which increase the size of the kernel/initrd is a good idea. You can always get them back by installing the extras package.

  • The kernel team also appears to have adopted this method for some of the mainline-PPA -generic kernels; the reasoning and solution remain the same -- if it looks like the base kernel image is missing a module you need, install extras.

  • As far as I know, the above approach has not been taken for the Quantal kernels -- only -virtual is affected as usual.

  • Note that I recommend simply using the latest Quantal kernel instead of the latest "mainline" kernel--on Precise--simply because the former is usually slightly more hardware-compatible. – ish Jun 19 '12 at 12:52
  • 1
    That's what I always do :) – Nikki Kononov Jun 19 '12 at 12:56
  • Btw, this is how you can see if the ..-extra is installed: dpkg --get-selections | grep linux-image – Timo Mar 12 '15 at 17:22
  • 1
    I wonder why is this obsolete? – Sajuuk Jan 4 at 7:49
  • @Sajuuk see answer below. It's obsolete because linux-image-extras is now more important than it used to be, and should not be removed from desktop systems. – Toby J Mar 2 at 2:52
up vote 14 down vote
+150

In previous Ubuntu versions, the linux-image-extras was optional, tailored for virtual machines / servers.

As of Ubuntu 14.04, linux-image is a slim package (for virtual machines), and linux-image-extras now contains many drivers required for desktops.

In particular, usb-hid (keyboard support), is only present once you install the linux-image-extras package. A common mishap, which results in TTY1 hanging on boot, and unable to login using a keyboard.

Mainline kernels are shipped using a single linux-image package, such as linux-image-3.19.0-031900rc1-generic_3.19.0-031900rc1.201412210135_amd64.deb

  • It also includes a bunch of network drivers your card might use. Bottom line: DO NOT uninstall this package. – Björn Lindqvist Nov 28 '15 at 19:12
  • Without linux-image-extras, my usb mouse worked fine, but my usb keyboard didn't. I'm sure this change from a -virtual package wastes a lot of people's time. – ferrouswheel Apr 6 at 3:00

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