libvirt users - May 2017 - Re: How to show underlying QEMU command line using virsh

Hello, everybody

I use virt to run my VM's and QEMU as a hypervisor. There is a file
describing my virtual machine:

/etc/libvirt/qemu/centos7.0.xml

As you know it contains xml representation of my VM. Is there any way to
show underlying qemu command that virsh runs using that file? For
example:

qemu-system-x86-64 -m 1024 -smp 2 -...

If no, is there any way to figure it out during VM run ?

---
Thanks in advance,
Roman Storozhenko

On Wed, May 24, 2017 at 10:49:23AM +0300, Roman Storozhenko
wrote:
> Hello, everybody
>
> I use virt to run my VM's and QEMU as a hypervisor. There is a file
> describing my virtual machine:
>
> /etc/libvirt/qemu/centos7.0.xml
Just a note, never edit ^these files directly behind libvirt's back and
always
use 'virsh edit' for all modifications.
>
> As you know it contains xml representation of my VM. Is there any way to
> show underlying qemu command that virsh runs using that file? For
> example:
virsh doesn't spawn the qemu process, it's a frontend to libvirtd daemon
which
will build the qemu cmdline according to the domain XML description and spawn
the process. As for the qemu commandline, we don't have an API to query the
command line, what you can do is get the qemu pid (e.g. with pgrep -f
<VM_name>
and then cat /proc/<pid>/cmdline) or use ps and pipe its output to grep.

Erik
>
> qemu-system-x86-64 -m 1024 -smp 2 -...
>
> If no, is there any way to figure it out during VM run ?
>
> ---
> Thanks in advance,
> Roman Storozhenko
>
> _______________________________________________
> libvirt-users mailing list
> libvirt-users@redhat.com
> https://www.redhat.com/mailman/listinfo/libvirt-users

On Wed, May 24, 2017 at 10:49:23AM +0300, Roman Storozhenko
wrote:
>Hello, everybody
>
>I use virt to run my VM's and QEMU as a hypervisor. There is a file
>describing my virtual machine:
>
>/etc/libvirt/qemu/centos7.0.xml
>
>As you know it contains xml representation of my VM. Is there any way to
>show underlying qemu command that virsh runs using that file? For
>example:
>
>qemu-system-x86-64 -m 1024 -smp 2 -...
>
>If no, is there any way to figure it out during VM run ?
>
There is virsh domxml-to-native, you can do:

  virsh dumpxml centos7.0 | virsh domxml-to-native qemu-argv /dev/stdin

However be warned that domxml-to-native does not support everything that
the driver will, this API is always a bit behind with some things.
>---
>Thanks in advance,
>Roman Storozhenko
>
>_______________________________________________
>libvirt-users mailing list
>libvirt-users@redhat.com
>https://www.redhat.com/mailman/listinfo/libvirt-users

On Wed, 24 May 2017 10:38:42 +0200
Erik Skultety <eskultet@redhat.com> wrote:
> On Wed, May 24, 2017 at 10:49:23AM +0300, Roman Storozhenko wrote:
> > Hello, everybody
> >
> > I use virt to run my VM's and QEMU as a hypervisor. There is a
file
> > describing my virtual machine:
> >
> > /etc/libvirt/qemu/centos7.0.xml  
> 
> Just a note, never edit ^these files directly behind libvirt's back and
always
> use 'virsh edit' for all modifications.
> 
> >
> > As you know it contains xml representation of my VM. Is there any way
to
> > show underlying qemu command that virsh runs using that file? For
> > example:  
> 
> virsh doesn't spawn the qemu process, it's a frontend to libvirtd
daemon which
> will build the qemu cmdline according to the domain XML description and
spawn
> the process. As for the qemu commandline, we don't have an API to query
the
> command line, what you can do is get the qemu pid (e.g. with pgrep -f
<VM_name>
> and then cat /proc/<pid>/cmdline) or use ps and pipe its output to
grep.
Or look in /var/log/libvirt/qemu/centos7.0.log. AFAIK the qemu command
gets logged every time you start the VM.

    Tomas
> 
> Erik
> 
> >
> > qemu-system-x86-64 -m 1024 -smp 2 -...
> >
> > If no, is there any way to figure it out during VM run ?
> >
> > ---
> > Thanks in advance,
> > Roman Storozhenko
> >
> > _______________________________________________
> > libvirt-users mailing list
> > libvirt-users@redhat.com
> > https://www.redhat.com/mailman/listinfo/libvirt-users  
> 
> _______________________________________________
> libvirt-users mailing list
> libvirt-users@redhat.com
> https://www.redhat.com/mailman/listinfo/libvirt-users

-- 
Tomáš Golembiovský <tgolembi@redhat.com>