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;
# modprobe -a kvm-intel tun virtio
Add users to kvm group;
# usermod -a -G kvm machine-admin
# usermod -a -G kvm username
Qemu supports multiple disk images types.
Create hard disk image, there is different types, this describes how to create a qcow2 type;
$ qemu-img create -f qcow2 crux-img.qcow2 20G
Qemu disk images can be treated as regular disks using qemu disk network block device server;
$ sudo modprobe nbd
$ sudo qemu-nbd -c /dev/nbd0 crux-img.qcow2
Information about preparing partitions and storage administration. You can use image as a normal disk, example how to use parted to create a gpt system table;
parted --script ${DEV} \
mklabel gpt \
unit mib \
mkpart primary 2 4 \
name 1 grub \
mkpart ESP fat32 4 132 \
name 2 efi \
mkpart primary ext4 132 1132 \
name 3 boot \
mkpart primary 1132 100% \
name 4 lvm \
set 1 bios_grub on \
set 2 boot on \
set 4 lvm on
# kpartx -a -s -l -u /dev/nbd0
Use /dev/mapper/$(name_of_device) to assign correct blocks;
pvcreate /dev/mapper/${DEV_NAME}p4
vgcreate vg_system /dev/mapper/${DEV_NAME}p4
lvcreate -L 15G -n lv_root vg_system
lvcreate -L 2G -n lv_var vg_system
lvcreate -l 100%FREE -n lv_home vg_system
mkfs.fat -F 32 /dev/mapper/${DEV_NAME}p2
mkfs.ext4 /dev/mapper/${DEV_NAME}p3
mkfs.ext4 /dev/vg_system/lv_root
mkfs.ext4 /dev/vg_system/lv_var
mkfs.ext4 /dev/vg_system/lv_home
Read lvm documentation on how to setup virtual group and logic volumes.
Mount partition;
mount /dev/vg_system/
mkdir -p $CHROOT/proc
mkdir -p $CHROOT/sys
mkdir -p $CHROOT/dev
mkdir -p $CHROOT/media
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}p5 $CHROOT/var
Before disconnecting image, clean dev mappings;
$ sudo kpartx -d /dev/nbd0
$ sudo qemu-nbd -d /dev/nbd0
Verify disk image information;
$ qemu-img info c1-storage.qcow2
image: c1-storage.qcow2 file format: qcow2 virtual size: 10G (10737418240 bytes) disk size: 7.6G cluster_size: 65536 Format specific information: compat: 1.1 lazy refcounts: false refcount bits: 16 corrupt: false $
In this example is added 25G to the image;
$ qemu-img resize c1-storage.qcow2 +25G
Read lvm resize if image is using lvm, or use resize2fs. If size is not provided to resize2fs, by default it will grow file system to all partition;
$ sudo qemu-nbd -c /dev/nbd0 /srv/qemu/img/c1-server.qcow2
# kpartx -a -s -l -u /dev/nbd0
GPT:Primary header thinks Alt. header is not at the end of the disk.
GPT:Alternate GPT header not at the end of the disk.
GPT: Use GNU Parted to correct GPT errors.
# parted /dev/nbd0
GNU Parted 3.2
Using /dev/nbd0
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print
Warning: Not all of the space available to /dev/nbd0 appears to be used, you can
fix the GPT to use all of the space (an extra 16777216 blocks) or continue with
the current setting?
Fix/Ignore? Fix
(parted) resizepart 3 100%
(parted) quit
# e2fsck /dev/mapper/nbd0p3
# resize2fs /dev/mapper/nbd0p3
Network configuration;
KERNEL=="tun", GROUP="kvm", MODE="0660", OPTIONS+="static_node=net/tun"
Create interface with correct permissions set for kvm group.
# 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
Create bridge, create new tap and add it to bridge;
DEV="br0"
ADDR=10.0.0.254
NET=10.0.0.0
GW=10.0.0.1
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: $0 [start|stop|restart]"
;;
esac
# End of file
See scripts/runvm/runvm.sh, as template. Example scripts;
runvm/profile/crux
mac=$(rmac_addr)
memory=1024
boot=d
tap="tap1"
iso=iso/crux-3.4.iso
image=img/crux-standard.qcow2
other="-vga std -display sdl"
runvm/runvm.sh
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} \
&
Set guests machines to run under the total resolution provided by host system configure grub on the guest with gfxmode;
Get current resolution on host machine;
$ xrandr --current | fgrep '*'
1366x768 60.00*+
Set grub gfxmod on guest machine, edit /etc/default/grub;
GRUB_GFXMODE=1366x768
GRUB_GFXPAYLOAD_LINUX=keep
Update grub configuration on guest machine;
# grub-mkconfig -o /boot/grub/grub.cfg
Check if DMAR is enable on kernel configuration, Intel and AMD uses different technology. To check on Inter machine run;
# grep -e DMAR -e IOMMU
runvm/profile/crux
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"
# lsusb
# ls /dev/v4l
# ls /dev/bus/usb
# chown root:kvm /dev/bus/usb/003/004
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"
# lsusb
# ls /dev/bus/usb
# chown root:kvm /dev/bus/usb/003/012
$ qemu-system-x86_64 -m 512 -enable-kvm -vnc :0 -usb -device usb-host,hostbus=3,hostaddr=12
Tools Index
This is part of the LeetIO System Documentation. Copyright (C) 2021 LeetIO Team. See the file Gnu Free Documentation License for copying conditions.