Re: [PATCH for 4.6 v2 3/3] xl/libxl: disallow saving a guest with vNUMA configured

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 09/09/2015 01:29 PM, Wei Liu wrote:
> On Wed, Sep 09, 2015 at 01:17:40PM -0400, Boris Ostrovsky wrote:
>> On 09/09/2015 01:03 PM, Wei Liu wrote:
>>> This is due to migration v2 frame record doesn't contain node
>>> information.
>>>
>>> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
>>> ---
>>> Cc: andrew.cooper3@citrix.com
>>> ---
>>>   docs/man/xl.cfg.pod.5   |  2 ++
>>>   tools/libxl/libxl_dom.c | 14 ++++++++++++++
>>>   2 files changed, 16 insertions(+)
>>>
>>> diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
>>> index 80e51bb..dbd0700 100644
>>> --- a/docs/man/xl.cfg.pod.5
>>> +++ b/docs/man/xl.cfg.pod.5
>>> @@ -263,6 +263,8 @@ virtual node.
>>>   Note that virtual NUMA for PV guest is not yet supported, because
>>>   there is an issue with cpuid handling that affects PV virtual NUMA.
>>> +Further more, guest with virtual NUMA cannot be saved or migrated
>>> +because node information of guest frames is not preserved.
>> Should we also issue a warning during startup if nomigrate is not set?
>>
> <dig dig>
>
> Ah, there is such option. I can certainly give a warning. The only
> problem is it seems to be stale in libxl, there is no code that checks
> that! I can still migrate a guest even with nomigrate set to true.
>
> Maybe someone with more knowledge about that option can lecture me on
> what that does? The manpage says it *enables* certain feature? Does that
> actually mean *make available*?

IIRC it was added to allow/control certain TSC modes (see domain_cpuid()).

-boris