libvirt users - Oct 2017 - "virsh define" modify xml configuration file

hi:
   I upgrade my system from rhel 7.3 to 7.4. so libvirt upgrade to 3.2.

   I found command "virsh define vm.xml" sometimes  modify
"vm.xml". I
thought the command will read vm.xml, not write to it. is this kind of
behavior by design?

   for example vm.xml with the line

   <cpu mode='custom' match='exact'>

   will be replaced with

  <cpu mode='custom' match='exact'
check='partial'>


Regards,
tbskyd

On 10/18/2017 06:59 AM, d tbsky wrote:
> hi:
>    I upgrade my system from rhel 7.3 to 7.4. so libvirt upgrade to 3.2.
>
>    I found command "virsh define vm.xml" sometimes  modify
"vm.xml".
That command would only modify the file "vm.xml" if it was located in
/etc/libvirt/qemu (or /etc/libvirt/lxc, or whatever was appropriate for
the domain type) *and* the domain's <name> happened to be
"vm". If
that's what's happening, this email should be your warning to never
directly modify or access the files in /etc/libvirt; they are files used
internally by libvirt, and modifying them can lead to "unexpected"
results.

>  I
> thought the command will read vm.xml, not write to it. is this kind of
> behavior by design?
>
>    for example vm.xml with the line
>
>    <cpu mode='custom' match='exact'>
>
>    will be replaced with
>
>   <cpu mode='custom' match='exact'
check='partial'>
>
>
> Regards,
> tbskyd
>
> _______________________________________________
> libvirt-users mailing list
> libvirt-users@redhat.com
> https://www.redhat.com/mailman/listinfo/libvirt-users
>

2017-10-19 9:48 GMT+08:00 Laine Stump
<laine@laine.org>:
> On 10/18/2017 06:59 AM, d tbsky wrote:
>> hi:
>>    I upgrade my system from rhel 7.3 to 7.4. so libvirt upgrade to 3.2.
>>
>>    I found command "virsh define vm.xml" sometimes  modify
"vm.xml".
>
> That command would only modify the file "vm.xml" if it was
located in
> /etc/libvirt/qemu (or /etc/libvirt/lxc, or whatever was appropriate for
> the domain type) *and* the domain's <name> happened to be
"vm". If
> that's what's happening, this email should be your warning to never
> directly modify or access the files in /etc/libvirt; they are files used
> internally by libvirt, and modifying them can lead to
"unexpected" results.
  got it. thanks a lot for the hint!

Regards,
tbskyd