Creating an image with Bifrost/Linux to be used with KVM
    --------------------------------------------------------

Andreas Wallin <andreas.wallin@uadm.uu.se>
It och inköp Uppsala University/Sweden


I hope that you find the description below useful. I start 
with creating a 1GB image file with the dd command called bifrost7.img 
in the /virtual directory (you can change this by changing IMGDIR). 
After that I partition that image file with sfdisk. Then we need a block 
device so that we can create a filesystem on the partition, we create 
that blockdevice by running kpartx (look at the output of the command so 
that you use the right loop-device in the following commands, 
/dev/mapper/loop0p was used in my example). After that we create a ext2 
filesystem with mkfs.ext2. After that I create a mountpoint for our 
filesystem, /mnt/bifrost in my example. Then I mount the filesystem, 
fetch bifrost7 and unpack the bifrost tar-file on our new filesystem. 
Then I copy some files needed to install grub from my local computer to 
the new filesystem. With the sed command I uncomment a line in 
/etc/inittab so that we get a serial console. Then I unmount the 
filesystem and starts grub so that we can install the grub bootloader on 
our imagefile. Please note that you need to provide the correct path and 
name of our image in the first line to grub "device (hd0) 
/virtual/bifrost7.img". After that I run e2label to set the label on our 
bifrost partition to bifrost. And then as a last thing I remove the 
previous created blockdevices. After that you should have an image that 
you can start from.

I did this on a computer running scientific linux 6.1 (x86_64). The 
machine I created uses the created diskimage as an IDE disk and for 
networking I specify an e1000 card.

Regards,
Andreas


===========

IMGDIR="/virtual"
MOUNTPOINT="/mnt/bifrost"

#
# Create raw image file
#
dd if=/dev/zero of=${IMGDIR}/bifrost7.img bs=1G count=1

#
# Create partition on image file
#
sfdisk --cylinders 977 --heads 64 --sectors 32 ${IMGDIR}/bifrost7.img << EOF
0 977 L *
,0
,0
,0
EOF

#
# Create block-device
#
kpartx -av ${IMGDIR}/bifrost7.img

# Previous command gives you a message similar to this
# add map loop0p1 (253:28): 0 2000895 linear /dev/loop0 1

#
# Create ext3 filesystem on first partition on image file
# with the help of the block device created with previous
# command
#
mkfs.ext2 -m0 /dev/mapper/loop0p

#
# Create mountpoint for bifrost partition
#
if [ ! -d ${MOUNTPOINT} ]; then
    mkdir ${MOUNTPOINT}
fi

#
# Mount bifrost partition on mountpoint
#
mount /dev/mapper/loop0p1 ${MOUNTPOINT}

#
# Download bifrost7 to tmp
#
cd /tmp/
wget 
http://ftp.sunet.se/pub/Linux/distributions/bifrost/v7/bifrost-rc-7.0-2.tar.gz

#
# Unpack bifrost7 files on partition
#
cd ${MOUNTPOINT}
tar xvzf /tmp/bifrost-rc-7.0-2.tar.gz

#
# Copy grub stage files to ${MOUNTPOINT}/boot/grub
#
cp /boot/grub/e2fs_stage1_5 ${MOUNTPOINT}/boot/grub
cp /boot/grub/stage1 ${MOUNTPOINT}/boot/grub
cp /boot/grub/stage2 ${MOUNTPOINT}/boot/grub
cp /boot/grub/vstafs_stage1_5 ${MOUNTPOINT}/boot/grub

#
# Activate serial console on ttyS0
#
cp ${MOUNTPOINT}/etc/inittab ${MOUNTPOINT}/etc/inittab.ORIGINAL
sed 's/#s1:45:respawn/s1:45:respawn/' ${MOUNTPOINT}/etc/inittab.ORIGINAL 
 > ${MOUNTPOINT}/etc/inittab

#
# Unmount bifrost partition
#
cd /
umount ${MOUNTPOINT}

#
# Install grub on image
# my image is located at /virtual/bifrost7.img
#
grub

device (hd0) /virtual/bifrost7.img
geometry (hd0) 977 64 32
root (hd0,0)
install (hd0,0)/boot/grub/stage1 (hd0) (hd0,0)/boot/grub/stage2 0x8000 p 
/boot/grub/menu.lst
quit

#
# Set filesystem label
#
e2label /dev/mapper/loop0p1 bifrost


#
# Destroy loopback blockdevice of image
#
kpartx -dl ${IMGDIR}/bifrost7.img