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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 https://doc.coreboot.org/. Contributions welcome!

Introduction

If you don't have a mainboard supported by LinuxBIOS don't worry: Qemu can help you to emulate one.

This nice tutorial was written by Alan Carvalho de Assis <acassis@gmail.com>.

Requirements

You need the following softwares:

GCC ie. v4.x
Qemu ie. v0.8.2
FILO ie. v0.5
LinuxBIOS ie. r2399

Creating FILO

Download FILO (I used filo-0.4.2.tar.bz2), decompress it, enter inside directory created.

First invocation of make creates the default Config file.

$ make

Edit this file as you like. The default configuration worked to me.

$ vi Config

Run make again to create filo.elf, the ELF FILO image.

$ make

You will need this file (filo.elf) to start Linux. This is used as a payload in LinuxBIOS, when executed it can load Linux kernel.

Creating LinuxBIOS

Download LinuxBIOS source code (I used LinuxBIOSv2-2394). Decompress it.

Change to directory targets/emulation/qemu-i386 and modify Config.lb to point to your filo.elf.

Return to targets directory and execute:

$ ./buildtarget emulation/qemu-i386

Go to targets/emulation/qemu-i386/qemu-i386 and execute:

$ make

It will create the file "qemu-bios.rom"

Rename this file to "bios.bin" and copy to your HOME directory.

Creating your disk image

Create a empty file (~ 200MB):

# dd if=/dev/zero of=disk.img bs=1M count=200

Format it as ext2:

# mkfs.ext2 -F disk.img

Mount it on somewhere:

# mount disk.img /mnt/rootfs -t ext2 -o loop

Now you need copy a root filesystem to it.

I create a directory /debian and used debootstrap command to create a basic root filesystem, but you can use any root filesystem from your distro (i.e. copy one from diskboot.img):

# cp -R /debian/* /mnt/rootfs

Open the file /mnt/rootfs/etc/inittab and change runlevel to level 1:

id:1:initdefault:

Change to /mnt/rootfs/boot and copy your default vmlinuz and initrd:

# cp /boot/vmlinuz-2.6.16-2-686 vmlinuz
# cp /boot/initrd.img-2.6.16-2-686 initrd

Change to /root and umount /mnt/rootfs:

# umount /mnt/rootfs

Exit of root account:

# exit

Starting LinuxBIOS in Qemu

Execute Qemu using the followings parameters:

$ qemu -L ~ -hda disk.img -nographic -no-kqemu -d in_asm,exec

When appear "boot:" text enter it:

boot: hda:/boot/vmlinuz root=/dev/hda initrd=/boot/initrd console=tty0 console=ttyS0,115200

QEMU Build Tutorial