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

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


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.


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.


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