Re: [PATCH RFC] improve the error message in "xl list --long"

[Jim Fehlig <jfehlig@suse.com>]

Ian Jackson wrote:
> Bamvor Jian Zhang writes ("Re: [Xen-devel] [PATCH RFC] improve the error message in "xl list --long""):
>   
>> considering this case, the user use virt-manager for management the virtual
>> machine, he would not aware of xm, xl or virsh is used by virt-manager and
>> vm-install. and it is safe to use the xm with virt-manager because the vm
>> info is only stored in xend not in libvirt. after user migrate from xm to
>> xl, he probably use the similar way. Acctually, our customer report this
>> bug because libvirt libxl driver still missing some apis compare with xl.
>> raising this message could let user know the circumstances.
>>     
>
> Thanks for the explanation.  I'm not sure I entirely follow, so I'm
> going to try to explain in my own words what I think you're saying:
>
> virt-manager users are used to using both xm and virsh to manage
> guests.  After moving to libxl this is even more relevant because of
> missing functionality in the libvirt libxl driver.  However, when a
> user uses xl on domains managed by virsh, things go wrong.  You want
> this to produce a better error message.
>   

I think that is a good summary, as I understand it.

> Is this right ?  If so I think some more details would be helpful to
> know what goes wrong.  It might be possible to make more of this work
> better, or to improve error messages some other way.
>   

A user reported the following when doing a xl long list of a domain
created by libvirt

homevhst01:~ # xl list smt
Name ID Mem VCPUs State Time(s)
smt 1 512 1 -b---- 861.4
homevhst01:~ # xl list --long smt
Domain name must be specified.

Hmm, user did provide a domain name.  This is the error Bamvor is trying
to improve.

> It would be possible in principle to make xl produce a warning when
> operating on a domain not created with xl, by looking for the missing
> userdata.

Yep, sounds reasonable to me.

Regards
Jim