Linux guest under KVM
I use:
- Host OS openSUSE 15.2 LEAP
- Random guests including Linux guests with virt-manager/virt-viewer
I had experienced weird problem where:
- guest openSUSE15.2 (5.3.18-lp152.19-default) sees all virt-manager's window resolutions (including
1366x768) - guest Ubuntu (kernel 4.4) did not see some higher resolutions even when Video RAM size (16MB) was enough. Maximum
was
1152x768
To ensure that it was not caused by Hypervisor settings I also cloned libvirt domain file (and change name, disk path and MAC address only).
While poking around QEMU sources (hw/display/qxl.c) I found this interesting note:
if (d->xres && d->yres) {
/* needs linux kernel 4.12+ to work */So I just upgraded Ubuntu kernel (4.4.0-31-generic) to kernel (4.13.0-16-generic) and problem resolved (now it seems same list of modes as openSUSE guest).
(Incomplete) resources:
- https://www.linux-kvm.org/page/SPICE
- https://serverfault.com/questions/874309/virt-manager-spice-copy-paste-doesnt-work
Mandatory requirements:
- must have Spice-vdagent installed and running. Using for example:
sudo apt-get install spice-vdagent
sudo systemctl enable spice-vdagentdBut it is FAR from emough. You must also have configured RedHat spice device:
- in your Virt-Manager
- click on "Add Hardware"
- click on "Channel" Device - ensure that Name is keep
com.redhat.spice.0 - save changes
Now poweroff and power on your Guest. Login to your guest and verify, that this device exists:
ls -l /dev/virtio-ports/
lrwxrwxrwx 1 root root 11 Apr 12 16:17 com.redhat.spice.0 -> ../vport2p1
If there is no /dev/virtio-ports/com.redhat.spice.0 then your Guest VM
configuration failed for some reason.
If there exist /dev/virtio-ports then your clipboard should really start working...
Many alternative Windows Managers (including LXDE and XFCE4) will not resize guest screen resolution. We must do it by ourselfs.
- Find you monitor output name:
xrandr --listmonitors Monitors: 1 0: +Virtual-1 1366/361x768/203+0+0 Virtual-1 - it is
Virtual-1in my case - now force update of screen resolution:
## Shared filesystem
How to share guest/host filesystem. I used (mostly) this guide:
- https://unix.stackexchange.com/questions/606816/error-adding-device-unsupported-configuration-only-supports-passthrough-access
My changes:
- remove leading slash from `Target` in VM Manage settings, for example:
- Target: `shared_vm`
And here is XML fragment of VM configuration:
```xml
<filesystem type="mount" accessmode="mapped">
<driver type="path"/>
<source dir="/var/local/shared_vm"/>
<target dir="shared_vm"/>
<alias name="fs0"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x08" function="0x0"/>
</filesystem>
Under Guest I use following entry in /etc/fstab:
shared_vm /mnt/shared_vm 9p trans=virtio,_netdev 0 0
NOTE: The _netdev is required to avoid too early attempt to mount 9p filesystem
on boot
(on many distributions that caused to enter emergency prompt).
Source: https://superuser.com/a/1565275
Sometimes we need virtual floppy (for example for Autoinst SUSE install).
NOTE: You can create autoinst.xml from running system using:
sudo yast clone_system
# will generate /root/autoinst.xmlIn my case (to reuse bare-metal autoinst.xml for VM install) I made these changes:
- disk name changed from
/dev/sdato/dev/vda - use PCI address for
eth0instead of MAC address for easier reuse
Here is resulting diff:
--- zotac-orig/autoinst.xml 2021-04-18 12:14:37.533228534 +0200
+++ zotac-virt-manager/autoinst.xml 2021-04-18 12:22:47.273319335 +0200
@@ -715,7 +715,7 @@
<bootproto>dhcp4</bootproto>
<mtu>0</mtu>
<name>eth0</name>
- <startmode>hotplug</startmode>
+ <startmode>auto</startmode>
</interface>
</interfaces>
<ipv6 config:type="boolean">false</ipv6>
@@ -723,20 +723,10 @@
<managed config:type="boolean">false</managed>
<net-udev config:type="list">
<rule>
- <name>wlan1</name>
+ <name>eth0</name>
<rule>KERNELS</rule>
<value>0000:01:00.0</value>
</rule>
- <rule>
- <name>eth0</name>
- <rule>ATTR{address}</rule>
- <value>00:01:2e:7a:5f:f8</value>
- </rule>
- <rule>
- <name>eth1</name>
- <rule>ATTR{address}</rule>
- <value>00:01:2e:7a:5f:f9</value>
- </rule>
</net-udev>
<routing>
<ipv4_forward config:type="boolean">false</ipv4_forward>
@@ -750,7 +740,7 @@
</ntp-client>
<partitioning config:type="list">
<drive>
- <device>/dev/sda</device>
+ <device>/dev/vda</device>
<disklabel>gpt</disklabel>
<enable_snapshots config:type="boolean">false</enable_snapshots>
<initialize config:type="boolean">false</initialize>WARNING! In reality you may have to also change partition sizes (YaST will warn if they will not fit to target and propose sensible changes to partition layout)
We can prepare such floppy using commands like:
- install requirements
sudo zypper in dosfstools mtools qemu-tools - create formatted empty floppy image (from: https://mail.gnome.org/archives/commits-list/2011-December/msg00811.html)
qemu-img create -f raw floppy.img 1440k /usr/sbin/mkfs.msdos -s 1 floppy.img
- now add to your
/etc/mtools.confvirtual letter and absolute path to your floppy image, for example:drive z: file="/home/hpaluch/ISOs/auto-inst/zotac-virt-manager/floppy.img" - and now you can easily list/copy files to this virtual floppy using commands like:
# creates label SUSE_INST on virtual floppy floppy.img mlabel z:SUSE_INST mdir z: # autoinst.xml is file in current directory mcopy autoinst.xml z: mdir z: - now you can attach your floppy to KVM VM, etc...
Example for Autoyast install on openSUSE LEAP 15.2:
- attach
openSUSE-Leap-15.2-DVD-x86_64.isoto created VM - attach floppy
floppy.imgto your VM - on boot you must specify parameter like:
autoyast=device://fd0/autoinst.xml ifcfg=eth0=dhcp - note: the
ifcfg=...was absolutely necessary to configure networketh0on install (all repository commands would otherwise fail) - when booted properly there must be
AutoYaST Settingsentry in installation wizard navigation tree (left pane).
Autoyast troubles:
- I got few strange errors that were not fatal - probably because there was temporary Internet connection failure.
Copyright © Henryk Paluch. All rights reserved.
