[libvirt] [PATCH v4 3/8] libxl: error out on not supported CPU mode, instead of silently ignoring

[Marek Marczykowski-Górecki]

On Mon, Feb 26, 2018 at 01:20:49PM -0700, Jim Fehlig wrote:
> On 02/15/2018 02:47 PM, Marek Marczykowski-Górecki wrote:
> > On Tue, Feb 13, 2018 at 09:02:35AM -0700, Jim Fehlig wrote:
> > > It looks like we never answered my question from V3, i.e. should we change
> > > the default mode in the post-parse callback if NUMA or CPU features are
> > > defined within <cpu>?
> > 
> > Hmm, but this means changing the config behind user's back, no?
> 
> Well, sort of. But it is really just making the implicit explicit.
> 
> > You have disabled nested HVM, upgrade, now you have enabled.
> > Global switch is some consolation here, but is it enough?
> 
> I _think_ so. With a global default that disables nesting, are there any
> scenarios you envision where a previously disabled nesting becomes enabled
> after upgrade?

Probably also importing VM from older libvirt. Not sure about migration?

Any other opinion about this? Daniel? Since introduction of global
switch I'm fine with either.

> BTW, I'm fine with this patch, just playing devil's advocate with handling
> such things post-parse vs domain start. It's not the only place where
> default xen config is not reflected in libvirt :-/.
> 
> Regards,
> Jim
> 
> > 
> > > It sure feels like such configuration tweaks and error checks should be
> > > handled in the parsing phase, similar to qemuDomainDefVcpusPostParse() and
> > > qemuDomainDefCPUPostParse() in the qemu driver. I think danpb is vaguely
> > > familiar with this series and can help answer that question. Daniel, do you
> > > have an opinion? Or a general comment about guidelines for checking/tweaking
> > > config in parse phase vs domain start phase?
> > 
> 

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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