Libvirt: how to pass qemu command line args?

Question

I have the current libvirt 1.2.20 i want to pass to my machine create with virt-manager some qemu flags. I edited the file and add

  </devices>
  <qemu:commandline>
          <qemu:arg value='-L pc-bios'/>
  </qemu:commandline>
</domain>

But doesn't work i also tried to edit from virsh

virsh edit domain

and put

<qemu:commandline>
          <qemu:arg value='-L pc-bios'/>
  </qemu:commandline>

But give me this error

errore: XML document failed to validate against schema: Unable to validate doc against /usr/share/libvirt/schemas/domain.rng
Element domain has extra content: qemu:commandline

Failed. Try again? [y,n,i,f,?]:

How to pass correctly qemu command line? Thanks

score 22 · Answer 1 · edited Nov 21 '18 at 19:24

22

elbarna's own answer is the way to go for configuration options "natively" supported by libvirt (and thus its domain XML). For qemu commandline arguments (and more) not supported by libvirt, you need to include qemu's XML namespace declaration in the 'domain' root element:

<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>

Reference: https://libvirt.org/drvqemu.html#qemucommand

edited Nov 21 '18 at 19:24

roolebo

111
4

answered Oct 21 '16 at 16:23

argonym

142
1
7

for servers who don't support kvm natively you can use `type='qemu'` – Jonas Libbrecht Feb 15 '17 at 14:10
2

That schema is 404 now. – Vilius Sutkus '89 May 19 '18 at 16:41
Seems they migrated to RelaxNG for the XML schemas. Though IDK if replacing above URL with `https://libvirt.org/schemas/domain.rng` works, if required at all. – argonym Jun 01 '18 at 12:56
@argonym No, does not seem to work out of the box. – Bostrot Sep 25 '18 at 23:03
1

I would add that in my case, parameters containing a space trigger an error, and must be given with multiple ` – Alex F Jan 22 '20 at 10:28
1

This still works, even if the schema is a 404. – Wieland Jun 07 '20 at 00:53
This doesn't append the args, so you cannot reference any `id` or pci bus created by the domain XML. – Johannes Schaub - litb May 25 '23 at 15:12

score 7 · Answer 2 · answered Jun 16 '19 at 18:32

If you have virt-xml 1.4.1 (released in 2017, so should be widespread by now) or later in your path (provided by community/virt-install in Arch), you can use:

virt-xml $DOMAIN --edit --confirm --qemu-commandline '-my-args 1234'
virt-xml $DOMAIN --edit --confirm --qemu-commandline 'env=MY-ENV=1234'

to automatically add the XML corresponding to env vars and/or args, including the namespace. --confirm allows you to preview the changes before committing.

This is much more convenient than trying to manually paste in the XML namespace, and worked for me even though virsh edit was no longer accepting identical manual changes.

Ref: https://blog.wikichoon.com/2017/03/easy-qemu-commandline-passthrough-with.html

score 3 · Accepted Answer · edited Oct 11 '15 at 23:15

3

Found solution using this workaround

Converting QEMU arguments to domain XML

After converting to xml import with

virsh create file.xml

edited Oct 11 '15 at 23:15

cas

1
7
119
185

answered Oct 11 '15 at 17:02

elbarna

12,050
22
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170

Libvirt: how to pass qemu command line args?

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