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<h1>Qemu</h1>
<h2 id="kern">1. Host System</h2>
<p>Prepare host system for virtual machines, this includes create new user,
loading necessary modules and configure network. Load kvm module, in this example
intel module is loaded but depends on host cpu;</p>
<pre>
# modprobe -a kvm-intel tun virtio
</pre>
<p>Add users to kvm group;</p>
<pre>
# usermod -a -G kvm c9admin
# usermod -a -G kvm username
</pre>
<h2 id="disk">2. Disk images</h2>
<p>Qemu supports multiple disk images types.</p>
<dl>
<dt>img</dt>
<dd>Raw disk image, allows dd to a physical device.</dd>
<dt>raw</dt>
<dd>Raw disk image, allows dd to a physical device.</dd>
<dt>qcow2</dt>
<dd>Qcow disk image file used by qemu.</dd>
</dl>
<p>Create hard disk image, there is different types,
this describes how to create a qcow2 type;</p>
<pre>
$ qemu-img create -f qcow2 crux-img.qcow2 2000M
</pre>
<h3 id="mount">2.1. Mount images</h3>
<p>Qemu disk images can be treated as regular disks using
qemu disk network block device server;</p>
<pre>
$ sudo modprobe nbd
$ sudo qemu-nbd -c /dev/nbd0 /crux-img.qcow2
</pre>
<p>Information about preparing
<a href="../core/install.html#step2">partitions</a>
and <a href="storage.html">storage</a> administration.
You can use image as a normal disk, example how
to use parted to create a gpt system table;</p>
<pre>
parted --script ${DEV} \
mklabel gpt \
unit mib \
mkpart primary 2 4 \
set 1 bios_grub on \
name 1 grub \
mkpart ESP fat32 4 59 \
set 2 boot on \
name 2 efi \
mkpart primary ext4 103 200 \
name 3 boot \
mkpart primary linux-swap 200 456 \
name 4 swap \
mkpart primary ext4 456 3700 \
name 5 root \
mkpart primary ext4 3700 4000 \
name 6 var \
mkpart primary ext4 4000 100% \
name 7 home
</pre>
<pre>
# kpartx -a -s -l -u /dev/nbd0
</pre>
<p>Use /dev/mapper/$(name_of_device) to assign correct blocks;</p>
<pre>
mkfs.fat -F 32 /dev/mapper/${DEV_NAME}p2
mkfs.ext4 /dev/mapper/${DEV_NAME}p3
mkswap /dev/mapper/${DEV_NAME}p4
mkfs.ext4 /dev/mapper/${DEV_NAME}p5
mkfs.ext4 /dev/mapper/${DEV_NAME}p6
mkfs.ext4 /dev/mapper/${DEV_NAME}p7
</pre>
<p>Mount partition;</p>
<pre>
mount /dev/mapper/${DEV_NAME}p5 $CHROOT
mkdir -p $CHROOT/proc
mkdir -p $CHROOT/sys
mkdir -p $CHROOT/dev
mkdir -p $CHROOT/boot
mount /dev/mapper/${DEV_NAME}p3 $CHROOT/boot
mkdir -p $CHROOT/boot/efi
mount /dev/mapper/${DEV_NAME}p2 $CHROOT/boot/efi
mkdir -p $CHROOT/var
mount /dev/mapper/${DEV_NAME}p6 $CHROOT/var
mkdir -p $CHROOT/home
mount /dev/mapper/${DEV_NAME}p7 $CHROOT/home
</pre>
<p>Before disconnecting image, clean dev mappings;</p>
<pre>
$ sudo kpartx -d /dev/nbd0
$ sudo qemu-nbd -d /dev/nbd0
</pre>
<h2 id="net">3. Network</h2>
<p>Network configuration;</p>
<dl>
<dt>slirp</dt>
<dd>Default virtual NAT'd network.</dd>
<dt>tun/tap</dt>
<dd>Good performance to create virtually any type of network
topology.</dd>
<dt>vde</dt>
<dd>The VDE networking backend.</dd>
</dl>
<pre>
KERNEL=="tun", GROUP="kvm", MODE="0660", OPTIONS+="static_node=net/tun"
</pre>
<h3>3.1. Routing</h3>
<p>Create interface with correct permissions set for kvm group.</p>
<pre>
# sysctl -w net.ipv4.ip_forward=1
# iptables -A INPUT -i br0 -j ACCEPT
# iptables -A FORWARD -i br0 -j ACCEPT
# iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -d 10.0.0.0/24 -j ACCEPT
# iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -j MASQUERADE
</pre>
<h3>3.2. Public Bridge</h3>
<p>Create <a href="network.html#bridge">bridge</a>, create new
tap and add it to bridge;</p>
<pre>
DEV="br0"
ADDR=10.0.0.254
NET=10.0.0.0
GW=192.168.1.254
MASK=24
# one tap for each cpu core
NTAPS=$((`/usr/bin/nproc`))
case $1 in
start)
/sbin/ip link add name ${DEV} type bridge
/sbin/ip addr add ${ADDR}/${MASK} dev ${DEV} broadcast +
/sbin/ip link set dev ${DEV} up
/bin/sleep 0.2s
for i in `/usr/bin/seq $NTAPS`
do
TAP="tap$i"
echo "Setting up ${TAP} tap interface."
/sbin/ip tuntap add ${TAP} mode tap group kvm
/sbin/ip link set ${TAP} up
/bin/sleep 0.2s
/sbin/ip link set ${TAP} master ${DEV}
done
exit 0
;;
stop)
for i in `/usr/bin/seq $NTAPS`
do
TAP="tap$i"
echo "Deleting ${TAP} tap interface."
/sbin/ip link del ${TAP}
done
/sbin/ip link set dev ${DEV} down
/sbin/ip route flush dev ${DEV}
/sbin/ip link del ${DEV}
exit 0
;;
restart)
$0 stop
$0 start
;;
*)
echo "Usage: $0 [start|stop|restart]"
;;
esac
# End of file
</pre>
<h2 id="guest">4. Guest System</h2>
<p>See <a href="scripts/runvm/runvm.sh">scripts/runvm/runvm.sh</a>,
as template. Example scripts;</p>
<p>runvm/profile/crux</p>
<pre>
mac=$(rmac_addr)
memory=1024
boot=d
tap="tap1"
iso=iso/crux-3.3.iso
image=img/crux-standard.qcow2
other="-vga std -display sdl"
</pre>
<p>runvm/runvm.sh</p>
<pre>
function rmac_addr (){
printf '54:60:BE:EF:%02X:%02X\n' $((RANDOM%256)) $((RANDOM%256))
}
source profile/$1
qemu-system-x86_64 \
-enable-kvm \
-m ${memory} \
-boot ${boot} \
-cdrom ${iso} \
-hda ${image} \
-device e1000,netdev=t0,mac=${mac} \
-netdev tap,id=t0,ifname=${tap},script=no,downscript=no \
${other} \
&
</pre>
<p>Set guests machines to run under the total resolution provided
by host system configure grub on the guest with gfxmode;</p>
<h3 id="graphics">4.1. Guest Graphics</h3>
<p>Get current resolution on host machine;</p>
<pre>
$ xrandr --current | fgrep '*'
1366x768 60.00*+
</pre>
<p>Set grub gfxmod on guest machine, edit /etc/default/grub;</p>
<pre>
GRUB_GFXMODE=1366x768
GRUB_GFXPAYLOAD_LINUX=keep
</pre>
<p>Update grub configuration on guest machine;</p>
<pre>
# update-grub
</pre>
<h3 id="sound">4.2. Guest Sound</h3>
<p>Check if DMAR is enable on kernel configuration,
Intel and AMD uses different technology. To check on
Inter machine run;</p>
<pre>
# grep -e DMAR -e IOMMU
</pre>
<p>runvm/profile/crux</p>
<pre>
export QEMU_AUDIO_DRV=alsa
memory=1024
boot=c
iso=iso/devuan_jessie_1.0.0_amd64_CD.iso
image=img/c12-dvd.qcow2
tap="tap2"
mac="54:60:be:ef:5c:72"
other="-soundhw hda -vga std -display sdl"
</pre>
<h3 id="usb">4.3. Guest USB</h3>
<pre>
# lsusb
# ls /dev/v4l
# ls /dev/bus/usb
</pre>
<pre>
# chown root:kvm /dev/bus/usb/003/004
</pre>
<pre>
export QEMU_AUDIO_DRV=alsa
memory=1024
boot=c
iso=iso/devuan_jessie_1.0.0_amd64_CD.iso
image=img/c12-dvd.qcow2
tap="tap2"
mac="54:60:be:ef:5c:72"
other="-soundhw hda -vga std -display sdl -usb -device usb-host,vendorid=0x13d3,productid=0x5652"
</pre>
<h2 id="bootusb">5. Boot iso on usb</h2>
<pre>
# lsusb
# ls /dev/bus/usb
</pre>
<pre>
# chown root:kvm /dev/bus/usb/003/012
</pre>
<pre>
$ qemu-system-x86_64 -m 512 -enable-kvm -vnc :0 -usb -device usb-host,hostbus=3,hostaddr=12
</pre>
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<p>This is part of the c9 Manual.
Copyright (C) 2018
c9 team.
See the file <a href="../fdl-1.3-standalone.html">Gnu Free Documentation License</a>
for copying conditions.</p>
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