Installing Debian via qemu

2009-01-08 3-minute read

I’ve been experimenting with kvm and qemu and run into some conceptual and practical problems. Here are some of my discoveries and short cuts.

I started by downloading the netinst Debian install image as debian-503-amd64-netinst.iso. Next I created an empty image:

	qemu-img create -f raw default.img 3GB 

This file will hold the virtual server.

Next, I launched the virtual server, booting from the debian installer, passing the file I just created as the first hard drive:

	 qemu-system-x86_64 -boot d -cdrom debian-503-amd64-netinst.iso -hda default.img -curses

This command is like booting a server with a single hard drive and the Debian install CD in the CD ROM drive (and configuring your bios to boot from the CD).

I pass the -curses option to tell qemu to not try to use the graphics card (since I’m doing this over ssh).

And here’s the real trick: Since the Debian installer tries to use frame buffers, I just got “640 x 480 Graphic Mode” on my screen. Following the Debian manual, I hit “Esc” on my keyboard and was magically dropped into text mode. Next I typed:

	install fb=false 

to launch the installer and ensure that frame buffer mode was disabled. From that point on I was taken through a text-based installation.

Everything went smoothly until the Grub install where I seemed to be hit with a qemu/grub 1 bug.

I killed the qemu process and made a bootable grub iso:

	mkdir -p grub/boot/grub
	cp /usr/lib/grub/x86_64-pc/stage2_eltorito grub/boot/grub/
	mkisofs -R -b grub/boot/grub/stage2_eltorito -no-emul-boot -boot-load-size 4 -boot-info-table -o grub.iso grub

Those steps created a file called grub.iso. I then booted with that file:

	 qemu-system-x86_64 -boot d -cdrom grub.iso -hda default.img -curses

And was dropped into a grub shell. I typed:

	root (hd0,0) 
	kernel /boot/vmlinuz-2.6.26-2-amd64 root=/dev/hda1 ro
	initrd /boot/initrd.img-2.6.26-2-amd64

And finally typed: boot and behold the installation booted!

Now the problem is… how do get grub properly installed??

Well… the solutions seems to be to install grub2. Before I could do that, I had to figure out how to get networking properly setup. Thanks to some help I changed the /etc/network/interfaces file on the host to:

	auto br0
	iface br0 inet static
		bridge_ports eth0

And edited /etc/qemu-up to:

	sudo -p "Password for $0:" /sbin/ifconfig $1 promisc up
	sudo /usr/sbin/brctl addif br0 $1

Then, I restarted the virtual server with:

	 qemu-system-x86_64 -boot d -cdrom grub.iso -hda default.img -curses -net nic -net tap

I went through the same grub business. Then, from inside the virtual host, I configured /etc/network/interfaces with a real IP address.

With network access, I installed grub2 and then ran:

	grub-intall /dev/hda
	shutdown -h now

And then restarted the virtual server with: qemu-system-x86_64 -hda default.img -curses -net nic -net tap

grub2 is graphical - so I can’t access it during the bootup (there’s probably a text mode command for grub2 somehwere).

At this point I finally got around to reading the README.Debian file in the qemu docs directory and learned about the Debian command qemu-make-debian-root. Wow. That’s makes things a lot easier.

According to the docs you can run:

	qemu-make-debian-root 3000 lenny debian.img

To use deboostrap to create a debian image. Then, launch with:

	qemu debian.img -kernel /vmlinuz

Haven’t gotten this to work though…

And another thing - I realized that I didn’t have kqemu installed (check for /dev/kqemu). I installed it with:

	aptitude install kqemu-sources

And then ran:


To build the module.

Followed by:

	modprobe -v kqemu

To load the module.