Correct way of downloading the running ubuntu 12.04 source code

Question

If I download the source code as:

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

In Makefile I can see

VERSION = 3
PATCHLEVEL = 2
SUBLEVEL = 55
EXTRAVERSION =

If I do this:

apt-get source linux-image-$(uname -r)

In Makefile I can see

VERSION = 3
PATCHLEVEL = 8
SUBLEVEL = 13
EXTRAVERSION = .19

None of the above two matches with my running kernel:

#lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04.4 LTS
Release:    12.04
Codename:   precise

Also:

3.8.0-38-generic #56~precise1-Ubuntu SMP Thu Mar 13 16:23:47 UTC 2014 i686 i686 i386 GNU/Linux

I understand I should have the exactly same source code that is running for developing and loading a driver using insmod. So how do I download the matching source code

Answer 1

Confusingly, the version number reported by uname does not correspond to the mainline kernel version in newer Ubuntu releases.

See this FAQ entry:
https://wiki.ubuntu.com/Kernel/FAQ#Kernel.2BAC8-FAQ.2BAC8-GeneralVersionToMainline.Given_an_Ubuntu_kernel_package_version_how_do_we_find_the_exact_mainline_release_it_is_based_on.3F

And the linked mapping table:
http://people.canonical.com/~kernel/info/kernel-version-map.html

Elsewhere on the FAQ page, you see how to query exact versions. On my 12.04.4 system, uname reports 3.2.0, but the upstream kernel used is 3.2.66:

user@host:~$ uname -r
3.2.0-77-generic
user@host:~$ cat /proc/version_signature 
Ubuntu 3.2.0-77.112-generic 3.2.66

If you check out tags/Ubuntu-3.2.0-77.112 from the precise kernel repo, you will see a Makefile with a SUBLEVEL of 66. The same is true for a tree installed via apt.