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I am planning to write some device drivers and I need to get the Linux kernel source. My Linux kernel version is 3.2.0-23-generic-pae and I downloaded the image from this. In many of the articles I have read, it tells me that I need to have the entire kernel tree to start inserting new modules.

Is it enough if I download this image and paste it into the usr/src/ folder or do I have to do something else?

Jorge Castro
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Sab
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5 Answers5

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This will get the source of the stock kernel:

apt-get source linux-source

You can check what version of the kernel is running like this:

uname -r

Which will print something like:

3.13.0-46-generic

You can find a list of current source package versions available on your system via:

apt-cache search linux-source

To get the upstream version of the kernel:

git clone git://kernel.ubuntu.com/ubuntu/ubuntu-trusty.git

In the above link, 'trusty' is the codename for the version of Ubuntu. You can find out the codename for the version of Ubuntu you have installed via:

cat /etc/lsb-release
Bryce
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    If I use git to clone how do i specify the version. Also If i Clone it is it enough if a I copy pate it into the usr/src folder – Sab Jul 05 '12 at 07:07
  • That git repository is kept to 3.2.0 specifically; it follows what's in Ubuntu Precise (12.04). If you want a different version change ubuntu-precise.git to ubuntu-quantal.git or whatever. It should be fine to just copy into usr/src. – Bryce Jul 05 '12 at 07:11
  • Okay.Thanks- But how did you find that git link? – Sab Jul 05 '12 at 07:15
  • Found it at https://wiki.ubuntu.com/KernelTeam/GitKernelBuild – Bryce Jul 05 '12 at 07:30
  • And where should I be able to find the source tree when installing with... Damn, I should read better. The answer says apt-get source not apt-get install. Than the source tree will end up in your current path. – Pro Backup Aug 12 '14 at 21:37
  • @Bryce How to know which version should I get?! – Dr.jacky Jul 22 '15 at 07:37
  • Mr. Hyde, I've elaborated on the answer, hope that helps. – Bryce Jul 23 '15 at 02:07
  • apt-get source only works for the latest kernel in the series, see below. – lemonsqueeze Jul 23 '17 at 14:43
  • This downloads 20 files, none of them C, in Ubuntu 20.04 LTS, – teknopaul Jun 13 '21 at 01:21
  • and it downloads the wrong version (not what uname -r reports) – teknopaul Jun 19 '21 at 11:18
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apt-get source linux

is the easiest way. It will download the source from your repository - and it'll be the same as the version you're running (assuming you haven't already customised it).

But if you want to find where the source is maintained you can run:

apt-cache showsrc linux

Look for the 'Vcs-' attribute (Version control system). It'll usually be a git (Vcs-Git) or mercurial repository.

Note - these commands work with any package. Just substitute 'linux' with the package you're interested in. And also note that 'apt-get source' doesn't need sudo access and will dump the source in your current directory.

Brendan McGrath
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  • This requires the machine you are downloading on to match the target machine. Really only works if you have a network. Most of the readers landing on this page won't have a network (hence why they suddenly need the source). I need it as a tarball on a thumb drive and I don't have a working apt. – mckenzm May 16 '16 at 20:01
  • This only downloaded the linux-headers into /usr/src - not the full kernel source - on Ubuntu 16.04 – Pierz Jan 08 '18 at 15:24
  • This downloading the src into the CURRENT DIRECTORY on Ubuntu 20.04 LTS, but it downloaded the wrong version of the kernel?? linux-5.4.0 when uname -r = 5.8.0-55-generic – teknopaul Jun 19 '21 at 11:28
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Just pick one from:

sudo apt install linux-source  # downloads into system directory
sudo apt source linux-source  # downloads into working directory

If you're told to give some 'sources' URLs in your sources.list, go edit your /etc/apt/sources.list file and uncomment the desired deb-src line, for example (if you're running Xenial):

deb http://fr.archive.ubuntu.com/ubuntu/ xenial main restricted
# deb-src http://fr.archive.ubuntu.com/ubuntu/ xenial main restricted

Removing the # on this last line enables sources repositories for download, including kernel sources.

Remarks:

  • Use modern tools; avoid apt-get.
  • These commands download the source code for your current kernel (in my case 4.4.0-75-generic for example).
  • When downloaded into system directory, files are stored in /usr/src/linux-source-4.4.0/ (for example).
Tim
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  • Doesn't work for me (but neither does the apt-get version). I'm running Ubuntu 16.04.4, kernel 4.4.0-98-generic. It says, "You must put some 'source' URIs in your sources.list". I have no idea how to do that. – Andrew Bainbridge Jan 09 '18 at 12:08
  • @AndrewBainbridge I added info about that. Is that OK for you now? – Tim Jan 10 '18 at 23:03
  • Yes thanks. It was a stupid comment from me. I only needed to google the error message. Anyway, have an upvote for your effort. – Andrew Bainbridge Jan 11 '18 at 11:03
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    this just downloads 19K of files not the millions on lines of C I was expecting – teknopaul Jun 13 '21 at 01:23
  • I had to call sudo apt-get update after the changes in sources.list-file. – Olivier Faucheux Apr 09 '23 at 04:41
  • I found the commented-out deb-src entries in /etc/apt/sources.list were for an older version, not the currently installed one. Ensure they match the "Codename:" from the command lsb_release -a (I had to edit mine). – Kingsley Apr 09 '23 at 20:43
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Download source directly from Launchpad

Strangely enough everyone recommends apt-get source which doesn't work most of the time if you're looking for a specific kernel version:

Say you need kernel source for 3.19.0-58 :
apt-get source linux-image-3.19.0-58-generic will get the source for the latest kernel in the series: 3.19.0-80 in this case, which is not what you asked for.

So you have two options:

1) Give up, install kernel 3.19.0-80 and use apt-get source

2) Get source directly from launchpad:

links

  • Put them in a new directory, unpack with dpkg-source -x *.dsc

Notes:

  • There must be a better way.
  • You can get the version you want from git, but you're in for a big download. See "Obtaining the kernel sources for an Ubuntu release using git" in Ubuntu Wiki Kernel Source Code.
lemonsqueeze
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    Thank you for explaining this so clearly. However, I am still unable to find the source for linux-image-4.15.0-39-generic. This process is needlessly complicated. I've tried googling for it but I keep finding packages that are a few kilobytes only. Any tips? – forgetso Nov 14 '18 at 19:00
  • This is the only option on this page that worked for Ubuntu 20.04 LTS to get something that claims to be a similar kernel version linux-5.8.0 to the one returned but uname -r – teknopaul Jun 19 '21 at 11:40
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There are cases where it is simply more practical to download the linux kernel source and headers for the version you're interested in directly from http://kernel.org (a pretty reliable URL/site that isn't going away [e.g. standard stackoverflow concern about stale links isn't not an issue])

Reason? For example, you might be interested in debugging an older/defunct no-longer-supported version of linux where package repository points to dead areas, where in some cases there are either no viable current alternatives, or the repos has are expired keys that won't let you get the stuff, requiring unmemorable difficult to search out arcane techniques to get those repositories to work anyway.

Or maybe Internet networking might be broken on Linux machine (or VM) you're using, but file sharing or NFS works, where the source can be downloaded onto another machine and accessed via the filesystem.

If you're working with a relatively obsolete version of Linux, chances are you'll have to build a number of things from source and get them the hard way.

clearlight
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    Thank you Community Bot, but I don't see how I can make it anymore helpful or clearer than what I have posted. I think your AI might need some tuning. – clearlight Feb 22 '22 at 21:38