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Re-compile a Debian kernel as a .deb package

Here is my success story on how to re-compile a Debian/Ubuntu kernel, in order to enable or tune kernel features which are not available as kernel modules:

# Install required software for the kernel compilation
apt-get install fakeroot build-essential devscripts
apt-get build-dep linux-image-$(uname -r) # make sure you have the appropriate "deb-src" in "sources.list"
apt-get install libncurses5-dev # required for "make menuconfig"
apt-get install ccache # to re-compile the kernel faster (http://wiki.debian.org/OverridingDSDT)

# Prepare some environent variables for our architecture, for later use
ARCH=$(uname -r|cut -d- -f3)
CPUCNT=$(( $(cat /proc/cpuinfo |egrep ^processor |wc -l) * 2))

# Get the kernel sources
rm -rf /root/krebuild && mkdir /root/krebuild
cd /root/krebuild
apt-get source linux-image-$(uname -r)
cd linux-$(uname -r|cut -d- -f1|cut -d. -f1-2)* # cd linux-3.2.20

# http://kernel-handbook.alioth.debian.org/ch-common-tasks.html # 4.2.5 Building packages for one flavour
# The target in this command has the general form of target_arch_featureset_flavour. Replace the featureset with none if you do not want any of the extra featuresets.

# Prepare a Debian kernel to compile
fakeroot make -f debian/rules.gen setup_${ARCH}_none_${ARCH} >/dev/null
cd debian/build/build_${ARCH}_none_${ARCH}
make menuconfig # make any kernel config changes now
cd ../../..

# No debug info => faster kernel build
perl -pi -e 's/debug-info:\s+true/debug-info: false/' debian/config/$ARCH/defines
echo binary-arch_${ARCH}_none_${ARCH}
vi debian/rules.gen # find the Make target and change DEBUG and DEBUG_INFO to False/n respectively

# Bugfix: http://lists.debian.org/debian-user/2008/02/msg01455.html
vi debian/bin/buildcheck.py +51 # add "return 0" right after "def __call__(self, out):"

# Compile the kernel
	fakeroot make -j$CPUCNT -f debian/rules.gen binary-arch_${ARCH}_none_${ARCH} > compile-progress.log

# If needed, the linux-headers-version-common binary package (http://kernel-handbook.alioth.debian.org/ch-common-tasks.html -> 4.2.5)
#fakeroot make -j$CPUCNT -f debian/rules.gen binary-arch_${ARCH}_none_real

# Install the newly compiled kernel
cd ..
dpkg -i linux-image-*.deb
#dpkg -i linux-headers-*.deb # only if you need them and/or have them installed already


Running Debian on Bifferboard

There are three major steps in installing Debian on your Bifferboard:

  1. Kernel boot command line.
  2. Kernel installation on the Bifferboard.
  3. Rootfs installation on a USB device or an SD/MMC card.

Kernel boot command line

Since Biffboot v3.3, dated 19.July.2010, the kernel boot command line no longer specifies an external block device for the root file system. As a result of this, you need to update the boot configuration before you can boot from a USB device or an SD/MMC card. You have two options to configure the boot command line:

You need to set the kernel boot command line (“Kernel cmndline”) to:

console=uart,io,0x3f8 root=/dev/sda1 rootwait

Kernel installation on the Bifferboard

Download a pre-built kernel binary image:

The kernel is compiled with (almost) all possible modules, so your Bifferboard should be able to easily use any device supported on Debian. Once you have downloaded the kernel image, you can then upload it to the Bifferboard, as advised at the Biffboot Wiki page. You have two options to upload the kernel – via the serial port or over the ethernet. Both work well.

Example: Assuming that you have the Bifferboard SVN repository checked out in “~/biffer/svn“, you have downloaded the “vmlinuz-” kernel image in “/tmp“, your Bifferboard has a MAC address of “00:B3:F6:00:37:A9“, and you have connected it on the Ethernet port “eth0” of your computer, here are the commands that you would need to use:

cd ~/biffer/svn/utils
sudo ./bb_eth_upload.py eth0 00:B3:F6:00:37:A9 /tmp/vmlinuz-

Rootfs installation on a USB device or an SD/MMC card

Once you have the kernel “installed” on the Bifferboard and ready to boot, you need to prepare a rootfs media. This is where your Debian installation is stored and booted from. Download one of the following pre-built rootfs images (default root password is “biffroot”):

The “developer” version adds the following packages: build-essential, perl, links, manpages, manpages-dev, man-db, mc, vim. Note that for each image you will need at least 100MB more free on the rootfs media.

In order to populate the rootfs media, you have to do the following:

  1. Create one primary partition, format it as “ext3” and then mount the USB device or SD/MMC card.
  2. Extract the archive in the mounted directory.
  3. Unmount the directory.

Example: Assuming that you have the Bifferboard SVN repository checked out in “~/biffer/svn“, you have downloaded the “minimal” rootfs image in “/tmp“, and you are using an SD/MMC card under the device name “/dev/mmcblk0“, here are the commands that you would need to use:

sudo bash
mkdir /mnt/rootfs
cd ~/biffer/svn/debian/rootfs
./format-and-mount.sh /dev/mmcblk0 /mnt/rootfs
tar -jxf /tmp/debian-lenny-bifferboard-rootfs-minimal.tar.bz2 -C /mnt/rootfs
umount /mnt/rootfs

When you have the USB device or SD/MMC card ready and populated with the customized Debian rootfs, plug it in Bifferboard, attach a serial cable to Bifferboard, if you have one, and boot it up.

That’s it. Enjoy your Bifferboard running Debian.

Update: As already mentioned in the comments below, you would probably need to set up swap too. Here is my recipe:

# change "128" (MBytes) below to a number which suits your needs
dd if=/dev/zero of=/swapfile bs=1M count=128
mkswap /swapfile
swapon /swapfile # enables swap right away; disable with "swapoff -a"
echo '/swapfile none swap sw 0 0' >> /etc/fstab # enables swap at system boot

Using a file for swap on a 2.6 Linux kernel has the same performances as using a separate swap partition as discussed at LKML.

Update 2: As announced by Debian, Debian 5.0 (lenny) has been superseded by Debian 6.0 (squeeze). Security updates have been discontinued as of February 6th, 2012. Thus by downloading and installing the images provided here, you’re using an obsolete Debian release. If that’s not a problem for you, read on. You need to change the file “/etc/apt/sources.list” to the following using your favorite text editor:

deb http://archive.debian.org/debian lenny main contrib non-free
deb-src http://archive.debian.org/debian lenny main contrib non-free
deb http://archive.debian.org/debian-security/ lenny/updates main contrib non-free
deb-src http://archive.debian.org/debian-security/ lenny/updates main contrib non-free

P.S. If you want to build your own customized Debian rootfs image for Bifferboard – checkout the Bifferboard SVN repository and review the instructions in “debian/rootfs/images.txt“.


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Build a Debian Linux kernel for Bifferboard as .deb packages

In my previous article I explained why and how to build a very small Linux kernel with all possible modules enabled which would help us to run a standard Debian installation on Bifferboard.

You can download the already built .deb packages for Debian “lenny” at the following addresses:

On my Bifferboard, I use the following Kernel command line to boot this kernel:

rootwait root=/dev/sda1 console=uart,io,0x3f8

For Qemu, because of some USB mass-storage emulation issues, the line looks like:

rootwait root=/dev/sda1 console=uart,io,0x3f8 irqpoll

Update: There are (more up-to-date) automated scripts which you can use for the below actions:

  • You need to checkout the whole Bifferboard SVN repository.
  • The scripts are located in the directory “/debian/kernel“. Execute the “build.sh” script from the checked out repository on your local computer, on a Debian “lenny” system.

If you want to build the packages yourself, you need to execute the following commands on a Debian “lenny” machine (a virtual machine or a chroot()’ed installation work too):

famzah@FURNA:~$ sudo apt-get install kernel-package fakeroot build-essential ncurses-dev tar patch
famzah@FURNA:~$ export KVERSION=
famzah@FURNA:~$ rm -rf /tmp/tmpkern-$KVERSION
famzah@FURNA:~$ mkdir /tmp/tmpkern-$KVERSION
famzah@FURNA:~$ cd /tmp/tmpkern-$KVERSION && wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-$KVERSION.tar.bz2
famzah@FURNA:/tmp/tmpkern-$ tar -xjf linux-$KVERSION.tar.bz2
famzah@FURNA:/tmp/tmpkern-$ sudo mkdir -p /usr/src/bifferboard && sudo chown $USER /usr/src/bifferboard
famzah@FURNA:/tmp/tmpkern-$ mv linux-$KVERSION /usr/src/bifferboard/
famzah@FURNA:/tmp/tmpkern-$ cd /usr/src/bifferboard/linux-$KVERSION
famzah@FURNA:/usr/src/bifferboard/linux-$ wget 'http://www.famzah.net/download/bifferboard/obsolete/bifferboard-' -O bifferboard-
famzah@FURNA:/usr/src/bifferboard/linux-$ patch --quiet -p1 < bifferboard-
famzah@FURNA:/usr/src/bifferboard/linux-$ wget http://www.famzah.net/download/bifferboard/obsolete/build-biff-kernel-
famzah@FURNA:/usr/src/bifferboard/linux-$ chmod +x build-biff-kernel-
famzah@FURNA:/usr/src/bifferboard/linux-$ ./build-biff-kernel-
# When "make menuconfig" is displayed, just EXIT and SAVE the configuration.
# After the build, you can find the two .deb packages in "/usr/src/bifferboard".

Used resources:

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Qemu .deb package for the RDC Bifferboard hardware

Following the instructions found at these articles, I build a .deb package for Qemu which is suitable for the RDC processor which is used by Bifferboard. The instructions and patches can be found at the official Qemu Wiki page of Bifferboard.

There is nothing special I’ve done here, just packaged the qemu binary, so that you can easily try the “qemu-rdc” binary. The download link follows:

Here are some simple instructions on how to test your own “bzImage” kernel build:

# Installation instructions for the .deb package and for the Qemu setup
famzah@FURNA:~$ wget http://www.famzah.net/download/bifferboard/qemu-rdc_0.10.5-1_i386.deb
famzah@FURNA:~$ sudo dpkg -i qemu-rdc_0.10.5-1_i386.deb
famzah@FURNA:~$ mkdir test-kernel
famzah@FURNA:~$ cd test-kernel/
famzah@FURNA:~/test-kernel$ svn co https://bifferboard.svn.sourceforge.net/svnroot/bifferboard/qemu/
famzah@FURNA:~/test-kernel$ cd qemu/run
famzah@FURNA:~/test-kernel/qemu/run$ vi run-qemu.sh # at the last line, change "qemu" with "qemu-rdc"

# You can now test your kernel/rootfs build. For example:
famzah@FURNA:~/test-kernel/qemu/run$ cp /home/famzah/biffer/qemu/custom_bzImage ./bzImage
famzah@FURNA:~/test-kernel/qemu/run$ QEMU_BIN=qemu-rdc ./run-qemu.sh

If you want to attach a USB mass-storage device and try your rootfs build there, please follow the instructions at the official Qemu Wiki page of Bifferboard on which parameters to add to “qemu-rdc” in “run-qemu.sh”.

You can exit the emulator by pressing CTRL+a and “x”. You will get some help info by pressing CTRL+a and “?”. See the man or documentation pages of “qemu” for more information.

In a few days I’ll post an article and a .deb package for a kernel build with (almost) all possible modules, suitable for running a native i386 Debian rootfs installation on Bifferboard.

P.S. Today I got my serial USB RS232 @ 3.3V cable and can now start with some real tests 😀