Recipe of the day: Cross-compiling armel kernels

ARM kernels can be very slow to bake because:
  1. ARM HW can be memory constrained so Native compilation is slow
  2. Setting up Native compilation for several boards is rather painful, if you, like me, have to compile several flavours everyday.
  3. Compiling under QEMU is mind-numbingly slow
Here, we bake all the Ubuntu ARM kernels using a single command on you x86 PC using a cross-compiler.

Ingredients
  1. A x86 machine running Ubuntu
  2. A ready-to-use cross-compilation toolchain
  3. Something software to compile, say, a kernel
Instructions
  • Get an ARM toolchain and set it up
I was too lazy to compile mine and got one from CodeSorcery. I used the 2008q3-72 tarball.

Untar it someplace in your $HOME, say $HOME/work/toolchains. You should now have a directory $HOME/work/toolchains/2008q3-72/bin with your cross-toolchain binaries.
  • Download the Ubuntu kernel
cd $HOME/work
git clone git://zinc.ubuntu.com/ubuntu/ubuntu-jaunty.git
cd ubuntu-jaunty
  • Compile the kernel
debuild -eCROSS_COMPILE=arm-none-linux-gnueabi- --prepend-path=$HOME/work/toolchains/arm-2008q3/bin -b -aarmel
  • Bake it
Let it bake for an hour or two, depending upon the speed of you oven^Wprocessor. If everything goes according to plan, you should have several .deb cookies for the various ARMel flavours of the Ubuntu kernel. Enjoy and share with friends and family.

Comments

Post a Comment

Popular posts from this blog

Prolonging the battery life on your laptop/netbook running Ubuntu

mdz pointed me to Idea 24782 over at Ubuntu Brainstorm that urges the Ubuntu community to increase focus on making Ubuntu run longer on devices with batteries. I support the idea wholeheartedly. Since the advent of laptops and netbooks, users have wanted to stretch the battery to last that extra 15 minutes it'll require for them to finish up their email or their documents. In fact, the most popular idea ever on Brainstorm is about fixing suspend and hibernate. Unfortunately, it ended up becoming a whirlpool of several different ideas, albeit with a common theme - making the battery last longer . There are several things that can be done to make the battery on a mobile device last longer - some under user control, others under OS/firmware control and some others dependent on HW capabilities. I am going to attempt to summarize the various use profiles and what Ubuntu does (or can do) to prolong battery life in those profiles. Power management, when done right, should not requi...
Read more

Ubuntu on ARM

So the wraps are off on this one - Ubuntu will soon come to a ARMv7-based SoC near you. Here are the press releases from ARM and Canonical if you are into reading those. I'm going to be adding support for several popular ARM-based devices to the Ubuntu kernel soon. Please refer to my other post to get familiar with nomenclature in the ARM world if you need. If you've followed Debian, they've had an armel port (ARM-endian-little), based on the new ARM ABI for a while now. A link to the excellent Debian EABI is in order for people interested in the nitty-gritty of ABIs. The Debian armel port is compiled for armv4t to support every ARM EABI-capable processor. Ubuntu is going to concentrate on ARMv7-based processors, including the Cortex-A8 and Cortex-A9. In practice, that would mean bootstrapping the distro for ARMv5 architecture and then optimizing critical libraries and applications for the ARMv7 architecture.
Read more

Speeding up boot on an upgraded system

So I have a laptop that I've been upgrading since Hardy (currently on Karmic Alpha) that I would like to boot faster. It has probably accumulated a lot of crufty daemons along the way that probably aren't being pre-loaded into memory. I picked up this tidbit from the fast boot expert . Add profile to your kernel command-line (at the grub prompt, press Esc e and then edit the line) . This will update your system's readahead file list after a lot of disk churn. On my machine, it sped up boot by only about 5 seconds, but YMMV. Also, if you have a machine or netbook with SSD (flash) disks, sreadahead might give you a boost. Again, apt-get install sreadahread is your friend . sreadahead also schedules profiling of the system every month-or-so, so it keeps those boot-essential programs in the readahead cache always.
Read more