Re: [Xen-devel] [v4][PATCH 11/19] tools: introduce some new parameters to set rdm policy

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

> > > This way of doing things is different than the way we do it with most
> > > other options relating to pci devices (e.g., pci_permissive,
> > > pci_msitranslate, pci_sieze, &c).  All of those options use a "default"
> > > semantic: the domain-wide setting takes effect only if it's not set
> > > locally.  If the syntax looks the same but the semantics is different,
> > > many people will be confused.  If we're going to have the domain-wide
> > > policy override the per-device policy, then the naming should make that
> > > clear; for instance, "override=(strict|relaxed|none)", or
> > > "strict_override=(1|0)".
> > Jan,
> >
> > What about this?
> >
> > This is involving our policy so please take a look at this as well.
> I don't think the way things get expressed in the domain config
> directly relates to what the policy is. How to best express things
> in the config I'd really like to leave to the tools maintainers.
Did you remember current definitions are from our previous discussion? 
From froce/try to strict/relaxed ...  You're always getting involved so 
much so we'd better listen what you would say at this point.
> > George,
> >
> > Actually we don't mean the domain-wide policy always override the
> > per-device policy, or the per-device policy always override the
> > per-device policy. Here we just take "strict" as the highest priority
> > when it conflicts in two cases. As I said previously myself may not
> > answer this very correctly but now I can recall or understand that one
> > reason is that different devices can share one RMRR entry, so its
> > possible that these two or more per-device policies are not same. So we
> > need this particular rule which is not same as before. So I still prefer
> > to keep our original implementation.
> >
> > If I'm missing something or wrong, please Jan correct me.
> I don't think I fully understand what you try to describe above;
> instead I think the global vs per-device settings should very much
> behave just like others (i.e. fallback to global if there is no per-
If there's no any explicit per-device setting from .cfg, per-device 
always has its own default setting, right?
> device setting). Furthermore, didn't we settle on not allowing
Let's make this clear.

Our current implementation is something like what I described in the 
patch head description,
Default per-device RDM policy is 'strict', while default global RDM 
policy is 'relaxed'. When both policies are specified on a given region, 
'strict' is always preferred.
Any concern to this? Or still let per-device policy override per-domain 
policy like others?

> pass-through of devices sharing RMRRs unless specifically told
> to by the admin (in which case part of what you write above
Yes we can ignore this case in current phase.

> would seem irrelevant to me)?
I just think when we're arguing current policy, you may have a good 
suggestion.
Thanks
Tiejun

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