[libvirt] [PATCH] docs: formatdomain: Specify the default value of 'check' attribute

[Kashyap Chamarthy]

On Wed, Jan 10, 2018 at 09:51:19AM +0100, Pavel Hrdina wrote:
> On Tue, Jan 09, 2018 at 08:28:20PM +0100, Jiri Denemark wrote:
> > On Tue, Jan 09, 2018 at 19:44:18 +0100, Kashyap Chamarthy wrote:
> > > On Tue, Jan 09, 2018 at 04:37:10PM +0100, Jiri Denemark wrote:

[...]
 
> One additional note for that virt-install command, this is the cpu
> part of XML definition created by virt-install:
> 
>   <cpu mode="custom" match="exact">
>     <model>Broadwell</model>
>   </cpu>
> 
> The cpu model will be different based on the host HW, but
> as you can see, there is no "check='full'.

Noted.  The admin has noticed the difference between the offline and
run-time definitions

> You can verify it by appending "--dry-run --print-xml" to your
> virt-install command which will do nothing and only print the
> XML definition.

Yep, this too the admin is aware.

Aside: is it expected that the run-time and offline config is
intentionaly different for the 'check' attribute?

Run-time:

    $> virsh start vm1
    $> virsh dumpxml vm1 | grep check
      <cpu mode='custom' match='exact' check='full'>
                                              ^^^^
Offline:

    $> virsh destroy vm1
    $> virsh dumpxml vm1 | grep check
      <cpu mode='custom' match='exact' check='partial'>
                                              ^^^^^^^

(Tried with: libvirt-daemon-kvm-3.7.0-2 and qemu-system-x86-2.10.0-4.)

[...]

> > >     sed -i -e "s-</cpu>-<feature policy='require' name='vme'/></cpu>-"
> > >     sed -i -e "s-</cpu>-<feature policy='require' name='arat'/></cpu>-"
> > 
> > This is some strange mangling of the XML by the admin for unclear
> > reason. It would be nice to finally see what the admin wanted to
> > achieve, what steps they did, and what result they saw.
> 
> Agreed, this is a mess.  

No, the XML updating is not the "mess" (that was required in his case).
The mess is how all this is subtly opaque to the admin.

> Just a note, if you need to edit XML
> and you would like to automate it, you can use virt-xml:
> 
>     virt-xml $domain --edit --cpu require=vme,require=arat

Yes, I already pointed that to the admin when he showed the `sed`
variant.

> Anyway, it shouldn't be needed to modify the XML in the first place.

It _was_ needed in his case (where updating QEMU broke).  See my other
reply to Jiri.

-- 
/kashyap