Building the Ubuntu 14.04 LTS kernel on Ubuntu 14.04 LTS

To experiment with device drivers in the self-hosted configuration (the target and the host are the same), the Linux kernel must first be built.  I started from a Ubuntu help page.

Clone Ubuntu git: just the source ma'am

I got the Trusty source

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

And then copy the config from /boot

• henry@Zotac64:~/work/ubuntu-trusty$ cp /boot/config-3.13.0-37-generic .config

Bring the config up to date with the latest kernel changes

• henry@Zotac64:~/work/ubuntu-trusty$ make oldconfig

Build the kernel (on for x64, don't need ARCH definition):

• henry@Zotac64:~/work/ubuntu-trusty$ make

When done, the vmlinux ELF file ready.  It's huge; even larger than the Buildroot rootfs for the  Zynq eval platform I've been using:

• henry@Zotac64:~/work/ubuntu-trusty$ ls -lh vmlinux
  -rwxrwxr-x 1 henry henry 151M Oct 23 19:18 vmlinux

Since this kernel should be compatible with my running kernel (where I am typing this blog entry) I can use this repository to write kernel modules and play around, WITHOUT changing my working kernel.

The "debian way": not so useful for kernel module development

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

Get the build tools with this command:

• sudo apt-get build-dep linux-image-$(uname -r)

Undefine CROSS_COMPILE, otherwise the build gets confused:

• export CROSS_COMPILE=

The kernel source is at ~/work/ubuntu/linux-3.13.0.  First generate the config files (use generic) with these commands:

• chmod a+x debian/scripts/*
  chmod a+x debian/scripts/misc/*
  fakeroot debian/rules clean
  fakeroot debian/rules editconfigs

After entering the last command, type 'n' a few times.  Build the kernel with this command:

• fakeroot debian/rules clean
  fakeroot debian/rules binary-headers binary-generic

If the build is successful, a set of three .deb binary package files will be produced in the directory above the build root directory, as you can see below:

• henry@Zotac64:~/work/ubuntu$ ls
  linux-3.13.0
  linux_3.13.0-37.64.diff.gz
  linux_3.13.0-37.64.dsc
  linux_3.13.0.orig.tar.gz
  linux-cloud-tools-3.13.0-37-generic_3.13.0-37.64_amd64.deb
  linux-headers-3.13.0-37_3.13.0-37.64_all.deb
  linux-headers-3.13.0-37-generic_3.13.0-37.64_amd64.deb
  linux-image-3.13.0-37-generic_3.13.0-37.64_amd64.deb
  linux-image-extra-3.13.0-37-generic_3.13.0-37.64_amd64.deb
  linux-tools-3.13.0-37-generic_3.13.0-37.64_amd64.deb