# Parallella (part 8): OS

By Mateusz Kaczanowski in ARM, Linux 0 Comment

Intro

Kernel, compiler, bsps, libraries, examples, userspace daemons… Because no one wants to deal with this alone, hardware manufactures (or community) often release pre-configured/customized OS distribution.
Adapteva is no exception and provides with parabuntu a fork of Ubuntu.

Let’s see how parabuntu diverges from mainline…

OS

Fortunately, parabutnu doesn’t include any major modifications. The changeset includes:

  • patched thermald for overheating protection (heat sink is not enough, trust me)
  • kernel + bootloader (u-boot) setup
  • partitioning scripts
  • toolchain packages (eSDK, OpenCL etc.)
  • FPGA bitstream packages

Yup, that’s pretty much it.

Arch Linux (alternative)

If you have seen my previous posts, likely you noticed, I am a huge fan of Arch Linux. If you’d like to switch the OS, here is a list of packages you can install to get the equivalent of parabuntu:

To build the whole system image, you can check out my previous blog post and use packer:

git clone https://github.com/mkaczanowski/packer-builder-arm
cd packer-builder-arm
go mod download
go build

sudo packer build boards/parallella/archlinuxarm.json

Packages

While writing package definitions (ie. RPM) is quite easy, the problem is with patching and versions… For example, it took me a good while to collect Epiphany kernel module files. Those are present upstream, but without dts files that would enable elink… If that wasn’t painful enough, the module didn’t work with the newer kernel version, too!

Here I want to highlight how many files you need to think about when you want to provide a proper kernel package for your platform:

source=(
        "http://www.kernel.org/pub/linux/kernel/v5.x/${_srcname}.tar.xz"
        "http://www.kernel.org/pub/linux/kernel/v5.x/patch-${pkgver}.xz"
        '0001-kernel-add-epiphany-kconfig.patch'
        '0002-kernel-add-epiphany-makefile.patch'
        'epiphany.c'
        'epiphany.h'
        'epiphany_uapi.h'
        'linux.preset'
        '60-linux.hook'
        '90-linux.hook'
        'linux-parallella.install'
        'config'
)

Summary

Again, coming up with a custom distro is pretty straightforward, but it does take a lot of effort. We need to take care of many system components and make sure those work continuously over time…

See other posts!