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--- workshop:libvirt_kvm [2010-06-22 21:04] – xro
+++ workshop:libvirt_kvm [2025-11-09 09:25] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-====== Workshop zu libVirt & KVM ======
+====== Workshop libVirt & KVM ======
-gehalten von Christian Pointner
-===== libvirt example =====
+  * by Christian Pointner
+  * workshop notes by Michael Prokop
+===== Ressources =====
+  * [[http://www.libvirt.org/]]
+  * man kvm
+===== Software =====
+Required software packages:
+<file>
+apt-get install libvirt-bin qemu-kvm qemu-utils
+</file>
+Graphical user interface:
+<file>
+apt-get install virt-manager
+</file>
+Kernel 2.6.32 and according libvirt highly recommended, e.g. Debian/squeeze and Debian/lenny with backports works fine.
+===== ifaces example =====
+<file>
+# This file describes the network interfaces available on your system
+# and how to activate them. For more information, see interfaces(5).
+# The loopback network interface
+auto lo
+iface lo inet loopback
+# bridge for kvm
+auto eth0
+iface eth0 inet manual
+auto vnet
+iface vnet inet dhcp
+    bridge_ports eth0
+</file>
+===== Simple demo setup with Grml ISO =====
 <file>
-<domain type='kvm' id='7'>
+cd /dev/shm
-  <name>kvm-vnc</name>
+wget http://download.grml.org/grml-small_2010.04.iso
-  <uuid>c4809964-9be7-4d66-2957-3a88743e2ac6</uuid>
+ISO=/dev/shm/grml-small_2010.04.iso
+cat > grml.xml << EOF
+<domain type='kvm'>
+  <name>grml-kvm</name>
   <memory>262144</memory>
   <currentMemory>262144</currentMemory>
   <vcpu>1</vcpu>
   <os>
-    <type arch='i686' machine='pc-0.12'>hvm</type>
+    <type arch='x86_64' machine='pc'>hvm</type>
     <boot dev='cdrom'/>
   </os>
@@ Line 25: / Line 70: @@
   <devices>
     <emulator>/usr/bin/kvm</emulator>
-    <disk type='block' device='disk'>
+    <disk type='file' device='cdrom'>
-      <driver cache='none'/>
-      <source dev='/home/equinox/Desktop/disks/kvm-graphic.img'/>
-      <target dev='vda' bus='virtio'/>
-      <alias name='virtio-disk0'/>
-      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
-    </disk>
-    <disk type='file' device='cdrom'>
       <driver name='qemu'/>
-      <source file='/home/equinox/Downloads/grml-small_2010.04.iso'/>
+      <source file='/grml/isos/grml-small_2010.04.iso'/>
       <target dev='hdc' bus='ide'/>
       <readonly/>
@@ Line 42: / Line 80: @@
     <controller type='ide' index='0'>
       <alias name='ide0'/>
-      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
     </controller>
     <interface type='bridge'>
-      <mac address='52:54:00:64:ab:1d'/>
+      <source bridge='vnet'/>
-      <source bridge='lan'/>
-      <target dev='vnet1'/>
       <model type='virtio'/>
       <alias name='net0'/>
-      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
     </interface>
     <serial type='pty'>
       <source path='/dev/pts/9'/>
       <target port='0'/>
-      <alias name='serial0'/>
+      <alias name='serial0'/>`
     </serial>
-    <console type='pty' tty='/dev/pts/9'>
+    <console type='pty'>
-      <source path='/dev/pts/9'/>
-      <target port='0'/>
-      <alias name='serial0'/>
     </console>
     <input type='mouse' bus='ps2'/>
-    <graphics type='vnc' port='5904' autoport='no'/>
+    <graphics type='vnc' autoport='yes'/>
-    <video>
-      <model type='cirrus' vram='9216' heads='1'/>
-      <alias name='video0'/>
-      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
-    </video>
   </devices>
 </domain>
+EOF
 </file>
-===== ifaces example =====
 <file>
-# This file describes the network interfaces available on your system
+sudo virsh [--connect qemu:///system]
-# and how to activate them. For more information, see interfaces(5).
+</file>
-# The loopback network interface
+Inside virsh then define and start grml instance:
-auto lo
-iface lo inet loopback
-# The primary network interface
+<file>
-# bridge for kvm
+virsh # define grml.xml
-auto eth0
+virsh # start grml-kvm
-iface eth0 inet manual
+</file>
-auto lan
+List VNC port:
-iface lan inet dhcp
-  bridge_ports eth0
+<file>
+virsh # vncdisplay grml-kvm
+:0
 </file>
-===== grub2 example =====
+List all defined instances:
 <file>
-GRUB_CMDLINE_LINUX_DEFAULT="quiet"
+virsh # list --all
-GRUB_CMDLINE_LINUX="quiet console=ttyS0,115200n8"
+ Id Name                 State
+----------------------------------
+grml-kvm             running
+</file>
-# Uncomment to disable graphical terminal (grub-pc only)
+List assigned serial console:
-#GRUB_TERMINAL=console
-GRUB_TERMINAL=serial
+<file>
-GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"
+virsh # ttyconsole grml-kvm
+/dev/pts/8
+</file>
+Connect via serial console (choose the "Serial" boot menu entry under additional entries for "grml-small" in the bootsplash to automatically enable serial console):
+<file>
+sudo -u libvirt-qemu cu -l /dev/pts/8
+</file>
+Connect via VNC:
+<file>
+vncviewer localhost:5900
+</file>
+Possible falltraps while setup:
+  * i686 vs. x86_64 as arch type
+  * missing any defined block devices
+  * missing bridge configuration as defined in config, example for /etc/network/interfaces see above
+Verify defined configuration:
+<file>
+define $FOO
+dumpxml $FOO
+</file>
+Autostart setup:
+<file>
+autostart $HOST
+net-auostart default
+net-autostart --disable default
+autostart --disable $HOST
+</file>
+Ballooning:
+<file>
+setmem $HOST 256000
+<currentMemory> <= <memory> -> but can be overriden via setmaxmem
+</file>
+Overbooking of CPU:
+<file>
+<vcpu>16</vcpu>
+</file>
+Tip: Disable caching in the virtualised instance so just the internal system (the system running inside the virtual machine) uses the caches (add this line inside every <disk> ... </disk> environment):
+<file>
+"<driver cache='none'/>"
+</file>
+===== Serial console access (guest) =====
+Adjust Grub2 configuration /etc/default/grub:
+<file>
+GRUB_CMDLINE_LINUX="console=ttyS0,115200n8"
+GRUB_SERIAL_COMMAND="serial --speed=1152200 --unit=0 --word=8 --parity=no --stop=1"
+</file>
+Adjust /etc/inittab for serial console access:
+<file>
+T0:23:respawn:/sbin/getty -L ttyS0 115200 vt100
+</file>
+==== Tips ====
+Convert file config in the native guest configuration format named by format to a domain XML format:
+<file>
+virsh [--connect qemu:///system domxml-to-native] domxml-to-native qemu-argv /dev/shm/grml.xml
+</file>
+virsh like console access to kvm/qemu:
+<file>
+kvm [...] -monitor stdio
+</file>
+Block device:
+<file>
+qemu-img create -f qcow2 block.img 1G
+    <disk type='block' device='disk'>
+      <driver cache='none'/>
+      <source dev='/dev/shm/block.img'/>
+      <target dev='vda' bus='virtio'/>
+      <alias name='virtio-disk0'/>
+    </disk>
 </file>
 ----
 {{tag>workshop}}