QEMU on FreeBSD, with Networking

Maybe you've heard of QEMU, an "open source processor emulator." It's not quite VMware, since there doesn't seem to be a concept of persistent state and there are definitely not snapshots. However, when I saw the variety of ready-to-run system images at OSZoo.org, I decided to try it on FreeBSD 6.0.

Luckily there are several QEMU ports. I installed emulators/qemu from the latest FreeBSD 6.0 package. I next installed emulators/kqemu-kmod using the port.

janney:/root# cd /usr/ports/emulators/kqemu-kmod
janney:/usr/ports/emulators/kqemu-kmod# make
=> kqemu-0.7.2.tar.gz doesn't seem to exist in /usr/ports/distfiles/kqemu.
=> Attempting to fetch from http://fabrice.bellard.free.fr/qemu/.
kqemu-0.7.2.tar.gz                            100% of   77 kB  102 kBps
===>  Extracting for kqemu-kmod-0.7.2_1
=> MD5 Checksum OK for kqemu/kqemu-0.7.2.tar.gz.
=> SHA256 Checksum OK for kqemu/kqemu-0.7.2.tar.gz.
===>  Patching for kqemu-kmod-0.7.2_1
===>  Applying FreeBSD patches for kqemu-kmod-0.7.2_1
===>  Configuring for kqemu-kmod-0.7.2_1
===>  Building for kqemu-kmod-0.7.2_1
Warning: Object directory not changed from original /usr/ports/emulators/kqemu-kmod/work/kqemu
@ -> /usr/src/sys
machine -> /usr/src/sys/i386/include
cc -O2 -fno-strict-aliasing -pipe -D_KERNEL -DKLD_MODULE -nostdinc -I-   -I. -I@ 
-I@/contrib/altq -I@/../include -I/usr/include -finline-limit=8000 -fno-common  
-mno-align-long-strings -mpreferred-stack-boundary=2  -mno-mmx -mno-3dnow -mno-sse -mno-sse2 
-ffreestanding -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes  -Wmissing-prototypes
-Wpointer-arith -Winline -Wcast-qual  -fformat-extensions -std=c99 -c kqemu-freebsd.c
ld  -d -warn-common -r -d -o kqemu.kld kqemu-mod-i386.o kqemu-freebsd.o
touch export_syms
awk -f /sys/conf/kmod_syms.awk kqemu.kld  export_syms | xargs -J% objcopy % kqemu.kld
ld -Bshareable  -d -warn-common -o kqemu.ko kqemu.kld
objcopy --strip-debug kqemu.ko
janney:/usr/ports/emulators/kqemu-kmod# make install
===>  Installing for kqemu-kmod-0.7.2_1
===>   Generating temporary packing list
===>  Checking if emulators/kqemu-kmod already installed
install -o root -g wheel -m 555   kqemu.ko /boot/kernel
kldxref /boot/kernel
if mount |/usr/bin/grep ^devfs >/dev/null ; then  : ;  else  if [ ! -e /dev/kqemu ]; then mknod 
/dev/kqemu c 250 0 ;  fi ;  /bin/chmod 666 /dev/kqemu ;  fi
===>   Registering installation for kqemu-kmod-0.7.2_1

Next I had to enable network connectivity. The host OS had xl0 as a live interface. QEMU would use the tap0 interface.

# cat /dev/null > /dev/tap0
# ifconfig tap0 create

# kldload bridge.ko
# sysctl net.link.ether.bridge_cfg=xl0,tap0
net.link.ether.bridge_cfg:  -> xl0,tap0
# sysctl net.link.ether.bridge.enable=1
net.link.ether.bridge.enable: 0 -> 1

I needed to create this small script to enable networking as well.

$ cat /etc/qemu-ifup 
#!/bin/sh
ifconfig ${1} 0.0.0.0 

Now I needed an image to run. I decided to use the NetBSD 2.0.2 x86 image, since it wasn't too large and I figured I would be familiar enough with NetBSD once it was running.

After downloading and extracting the image, I was ready to try running it.

# qemu -net nic -net tap netbsd_2.0.2.img

Here is the initial boot screen.



Now the system is booted.



The root login for this system image is "piripicchio" (it's Italian). Once logged in, I configured the ne2 interface with an IP address on the same segment as the host OS.



Next I added a default route, a nameserver, and a normal user account with a password.

# route add default 192.168.2.1
# echo "nameserver 192.168.2.1" > /etc/resolv.conf
# useradd -m richard
# passwd richard

Now I wanted to enable sshd. After trying to just start the daemon, I realized I needed to generate at least a DSA key as shown below.



With sshd listening, I could log in remotely.

$ ssh 192.168.2.77
The authenticity of host '192.168.2.77 (192.168.2.77)' can't be established.
DSA key fingerprint is 5d:7f:a2:08:b0:3f:f7:e2:45:35:79:60:45:50:09:5d.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.2.77' (DSA) to the list of known hosts.
richard@192.168.2.77's password: 
NetBSD 2.0.2 (GENERIC) #0: Wed Mar 23 08:53:42 UTC 2005

Welcome to NetBSD!

Erase is backspace.                                                     
If one studies too zealously, one easily loses his pants.
                -- A. Einstein.
: {1} uname -a
NetBSD  2.0.2 NetBSD 2.0.2 (GENERIC) #0: Wed Mar 23 08:53:42 UTC 2005  
jmc@faith.netbsd.org:/home/builds/ab/netbsd-2-0-2-RELEASE/i386/200503220140Z
-obj/home/builds/ab/netbsd-2-0-2-RELEASE/src/sys/arch/i386/compile/GENERIC i386
: {2} df -h
Filesystem    Size     Used     Avail Capacity  Mounted on
/dev/wd0a     846M     291M      513M    36%    /
kernfs        1.0K     1.0K        0B   100%    /kern

I think that is pretty cool for a free virtual machine. As I learn more about QEMU I will share it here.

I found these three posts to be helpful when getting QEMU working.