Re: [Xen-devel] (v2) Design proposal for RMRR fix

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.01.15 at 10:43, <kevin.tian@xxxxxxxxx> wrote:
>>  From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Wednesday, January 14, 2015 5:00 PM
>> 
>> >>> On 14.01.15 at 09:06, <kevin.tian@xxxxxxxxx> wrote:
>> > Now the open is whether we want to fail domain creation for all of above
>> > conflicts. user may choose to bear with conflicts at his own disposal, or
>> > libxl doesn't want to fail conflicts as preparation for future
>> > hotplug/migration.
>> > One possible option is to add a per-region flag to specify whether treating
>> > relevant conflict as an error, when libxl composes the list to domain
>> > builder.
>> > and this information will be saved in a user space database accessible to
>> > all components and also waterfall to Xen hypervisor when libxl requests
>> > actual device assignment.
>> 
>> That's certainly a possibility, albeit saying (in the guest config) that
>> a region to be reserved only when possible is about the same as
>> not stating that region. If at all, I'd see the rmrr-host value be a
>> tristate (don't, try, and force) to that effect.
>> 
> 
> how about something like below with bi-state?
> 
> for statically assigned device:
>       pci = [ "00:02.0, 0/1" ]
> where '0/1' represents try/force (or use 'try/force', or have a meaningful 
> attribute like rmrr_check=try/force?)

As said many times before, for statically assigned devices such a flag
makes no sense.

> for other usages like hotplug/migration:
>       reserved_regions = [ 'host, 0/1', 'start, end, 0/1', 'start, end, 0/1', 
> ...]
> If 'host' is specified, it implies rmrr_host, besides user can specific 
> explicit ranges according to his detail requirement.

For host the flag makes sense, but for the explicitly specified regions
- as said before - I don't think it does.

Jan


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