From: Petter Reinholdtsen <pere@hungry.com>
Date: Sun, 27 Oct 2013 15:53:09 +0000 (+0000)
Subject: New post.
X-Git-Url: https://pere.pagekite.me/gitweb/homepage.git/commitdiff_plain/9bf345ab6c3805bc718fc29dbfffeef8565e0cab?ds=sidebyside

New post.
---

diff --git a/blog/data/2013-10-27-vmdebootstrap-rpi.txt b/blog/data/2013-10-27-vmdebootstrap-rpi.txt
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+Title: Teaching vmdebootstrap to create Raspberry Pi SD card images
+Tags: english, freedombox, mesh network
+Date: 2013-10-27 17:00
+
+<p>The
+<a href="http://packages.qa.debian.org/v/vmdebootstrap.html">vmdebootstrap</a>
+program is a a very nice system to create virtual machine images.  It
+create a image file, add a partition table, mount it and run
+debootstrap in the mounted directory to create a Debian system on a
+stick.  Yesterday, I decided to try to teach it how to make images for
+<a href="https://wiki.debian.org/RaspberryPi">Raspberry Pi</a>, as part
+of a plan to simplify the build system for the FreedomBox project.
+The FreedomBox project already uses vmdebootstrap for the virtualbox
+images, but its home made multistrap based system for Dreamplug
+images, and it is lacking support for Raspberry Pi.</p>
+
+<p>Armed with the knowledge on how to build "foreign" (aka non-native
+architecture) chroots for Raspberry Pi, I dived into the vmdebootstrap
+code and adjusted it to be able to build armel images on my amd64
+Debian laptop.  I ended up giving vmdebootstrap five new options,
+allowing me to replicate the image creation process I use to make
+<a href=http://people.skolelinux.org/pere/blog/A_Raspberry_Pi_based_batman_adv_Mesh_network_node.html"">Debian
+Jessie based mesh node images for the Raspberry Pi</a>.  First, the
+<tt>--foreign /path/to/binfm_handler</tt> option tell vmdebootstrap to
+call debootstrap with --foreign and to copy the handler into the
+generated chroot before running the second stage.  This allow
+vmdebootstrap to create armel images on a amd64 host.  Next I added
+two new options <tt>--bootsize size</tt> and <tt>--boottype
+fstype</tt> to teach it to create a separate /boot/ partition with the
+given file system type, allowing me to create an image with a vfat
+partition for the /boot/ stuff.  I also added a <tt>--variant
+variant</tt> option to allow me to create smaller images without the
+Debian base system packages installed.  Finally, I added an option
+<tt>--no-extlinux</tt> to tell vmdebootstrap to not install extlinux
+as a boot loader.  It is not needed on the Raspberry Pi and probably
+most other non-x86 architectures.  The changes were accepted by the
+upstream author of vmdebootstrap yesterday and today, and am now
+available from
+<a href="http://git.liw.fi/cgi-bin/cgit/cgit.cgi/vmdebootstrap/">the
+upstream project page</a>.</p>
+
+<p>To use it to build a Raspberry Pi image using Debian Jessie, first
+create a small script (the customize script) to add the non-free
+binary blob needed to boot the Raspberry Pi and the APT source
+list:</p>
+
+<p><pre>
+#!/bin/sh
+set -e # Exit on first error
+rootdir="$1"
+cd "$rootdir"
+cat <<EOF > etc/apt/sources.list
+deb http://http.debian.net/debian/ jessie main contrib non-free
+EOF
+# Install non-free binary blob needed to boot Raspberry Pi.  This
+# install a kernel somewhere too.
+wget https://raw.github.com/Hexxeh/rpi-update/master/rpi-update \
+    -O $rootdir/usr/bin/rpi-update
+chmod a+x $rootdir/usr/bin/rpi-update
+mkdir -p $rootdir/lib/modules
+touch $rootdir/boot/start.elf
+chroot $rootdir rpi-update
+</pre></p>
+
+<p>Next, fetch the latest vmdebootstrap script and call it like this
+to build the image:</p>
+
+<pre>
+sudo ./vmdebootstrap \
+    --variant minbase \
+    --arch armel \
+    --distribution jessie \
+    --mirror http://http.debian.net/debian \
+    --image test.img \
+    --size 600M \
+    --bootsize 64M \
+    --boottype vfat \
+    --log-level debug \
+    --verbose \
+    --no-kernel \
+    --no-extlinux \
+    --root-password raspberry \
+    --hostname raspberrypi \
+    --foreign /usr/bin/qemu-arm-static \
+    --customize `pwd`/customize \
+    --package netbase \
+    --package git-core \
+    --package binutils \
+    --package ca-certificates \
+    --package wget \
+    --package kmod
+</pre></p>
+
+<p>The list of packages being installed are the ones needed by
+rpi-update to make the image bootable on the Raspberry Pi, with the
+exception of netbase, which is needed by debootstrap to find
+/etc/hosts with the minbase variant.</p>
+
+<p>The build host need debootstrap, kpartx and qemu-user-static and
+probably a few others installed.  I have not checked the complete
+build dependency list.</p>
+
+<p>The resulting image will not use the hardware floating point unit
+on the Raspberry PI, because the armel architecture in Debian is not
+optimized for that use.  So the images created will be a bit slower
+than <a href="http://www.raspbian.org/">Raspbian</a> based images.</p>