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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?

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up vote 30 down vote accepted

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.

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Thank you very much for the explanation. – Nikki Kononov Jun 19 '12 at 12:48
    
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. – izx 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

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

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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

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