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Revision as of 13:32, 25 October 2007 by Phs (talk | contribs) (Booting FreeBSD inside QEMU)
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Documentation is now handled by the same processes we use for code: Add something to the Documentation/ directory in the coreboot repo, and it will be rendered to Contributions welcome!

This article describes how to build LinuxBIOS v2 on FreeBSD and boot FreeBSD using LinuxBIOS and ADLO inside Qemu.


All steps outlined in this article have been performed using FreeBSD 7.0-BETA1. Other versions of FreeBSD might work, too, but have not been tested. The patches mentioned in this article have been created against LinuxBIOSv2, Revision 2897.

In order to build ADLO on FreeBSD, you need the following ports installed:

To build LinuxBIOS on FreeBSD, you need

  • devel/gmake
  • lang/python. At the time of writing this article, that port installs Python 2.4. Possibly other version of Python also work but haven't been tried.

To boot FreeBSD in QEMU you need

Obtaining LinuxBIOS

See this page on how to download LinuxBIOS. I recomment you checkout the latest Version of LinuxBIOS v2 using Subversion.

Applying the required patches

The LinuxBIOS build process assumes that the make utility is GNU make. This isn't true on FreeBSD (or the other BSDs for that matter), where GNU make is installed as gmake.

A patch which addresses this can be found here. To download and apply this patch, run the following commands from the top-level directory of your LinuxBIOS source tree (e.g. /home/phs/LinuxBIOSv2):

$ ftp
$ tar xzf LinuxBIOS_ADLO_FreeBSD.tgz
$ patch -p0 < LinuxBIOS_ADLO_FreeBSD.diff

Building ADLO

In order to boot FreeBSD using LinuxBIOS, ADLO is used as a payload. Therefore, it must be build before the LinuxBIOS image can be built. Building ADLO on FreeBSD requires that the 8086 development environment is installed. See the following section for details.

ADLO is part of the LinuxBIOS v2 source tree. Assuming you have applied the required patches, it can be build by issuing the following commands from the top-level directory of your LinuxBIOS v2 source tree:

$ cd util/ADLO
$ gmake

You will now find the ADLO payload at util/ADLO/payload.

Building the 8086 development environment

ADLO requires the devel/dev86 port which installs the 8086 development environment. This is a new port not yet included in the FreeBSD Ports tree, see Problem Report ports/117480. To build the port, download and extract the shell archive attached to the problem report.

$ ftp -o devel_dev.shar
$ sh devel_dev.shar
$ cd dev86
$ su
# make install

This has to be done only once, before building ADLO. You don't have to reinstall the port if you rebuild ADLO.

Building LinuxBIOS

The QEMU build tutorial covers all steps required to build LinuxBIOS for QEMU. As a quick reference, assuming you have applied the required patches do:

$ cd targets
$ ./buildtarget emulation/qemu-i386
$ cd emulation/qemu-i386/qemu-i386
$ gmake

Make sure you use the gmake utility on FreeBSD!

Booting FreeBSD inside QEMU

If you already have a FreeBSD installation inside QEMU, you can boot it using LinuxBIOS with the following command:

$ qemu -kernel-kqemu -hda freebsd.img -nographic -L .

This assumes, that there is a file called bios.bin in the current working directory that contains LinuxBIOS with an ADLO payload. The file freebsd.img should contain your FreeBSD installation. Make sure it uses the serial console, though, as graphical output will not work when booted using LinuxBIOS.

Installing FreeBSD inside QEMU

Installing FreeBSD inside QEMU is pretty straight forward. If you already have a working installation, you can skip this section.

First you need to create a QEMU disk:

$ qemu-img create freebsd.img 1024M

This will create a QEMU virtual disk named freebsd.img with a capacity of 1 GByte. Next, install the base system using one of the ISO files provided by the FreeBSD Project at and have QEMU use it as the boot device. In this example, the FreeBSD 7.0-BETA1 bootonly disc [1] is used:

$ qemu -kernel-kqemu -hda freebsd.img -cdrom 7.0-BETA1-i386-bootonly.iso -boot d

Inside the QEMU, perform an installation as you normally would. See the FreeBSD Handbook for details. After the installation has finished, boot up FreeBSD once without using LinuxBIOS.

$ qemu -kernel-kqemu -hda freebsd.img

In the FreeBSD installation running inside QEMU add the following to the file /boot/loader.conf:


This will cause FreeBSD to use the first serial port as a console. Both the Loader's and the Kernel's messages will end up there. This is important as graphical output won't work once FreeBSD is booted using LinuxBIOS and ADLO.