We are going to work with a QEMU wrapper, called virtme. Virtme is a set of simple tools to run a virtualized Linux kernel. It can boot a kernel using the host Linux distribution or a simple rootfs instead of a whole disk image. Virtme is tiny, easy to use, and makes testing kernel changes quite simple. You can read more about QEMU here, and more about virtme here.

In order to work through the exercises, we need to setup a couple things first.

Getting dependencies¶

For Ubuntu 16.04, Ubuntu 18.x, Debian Jessie or Debian Stretch, the following will work:

apt-get -y -q install          \
  bc                           \
  flex                         \
  bison                        \
  build-essential              \
  git                          \
  libncurses-dev               \
  libssl-dev                   \
  libelf-dev                   \
  u-boot-tools                 \
  wget                         \
  xz-utils                     \
  qemu-kvm                     \
  iproute2                     \
  python3                      \
  python3-pip

The package list may be different on other Ubuntu versions, or other distributions.

For Arch Linux and derivatives (x86_64)

pacman -S base-devel git ncurses libelf uboot-tools qemu python-pip

Installing virtme¶

pip3 install --user git+https://github.com/arighi/virtme.git

Building a kernel¶

cd ~
git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
cd linux
virtme-configkernel --defconfig
make oldconfig
make -j8

Running your kernel¶

cd ~/linux
virtme-run --kimg arch/x86/boot/bzImage
[...]

If everything went OK, you'll be booting a kernel inside a QEMU instance. In order to quit the QEMU instance, you can use Ctrl-A X.