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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 12.01.15 at 12:41, <kevin.tian@xxxxxxxxx> wrote:
>>  From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Monday, January 12, 2015 7:37 PM
>> 
>> >>> On 12.01.15 at 12:22, <kevin.tian@xxxxxxxxx> wrote:
>> >>  From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> >> Sent: Monday, January 12, 2015 6:23 PM
>> >> One of my main problems with all you recent argumentation here
>> >> is the arbitrary use of the 1Gb boundary - there's nothing special
>> >> in this discussion with where the boundary is. Everything revolves
>> >> around the (undue) effect of report-all on domains not needing all
>> >> of the ranges found on the host.
>> >>
>> >
>> > I'm not sure which part of my argument is not clear here. report-all
>> > would be a problem here only if we want to fix all the conflictions
>> > (then pulling unnecessary devices increases the confliction possibility)
>> > in the domain builder. but if we only fix reasonable ones (e.g. >3GB)
>> > while warn other conflictions (e.g. <3G) in domain builder (let later
>> > assignment path to actually fail if confliction does matter),
>> 
>> And have no way for the user to (securely) avoid that failure. Plus
>> the definition of "reasonable" here is of course going to be arbitrary.
> 
> actually here I didn't get your point then. It's your proposal to make 
> reasonable assumption like below:
> 
> ---
> d) Move down the lowmem RAM/MMIO boundary so that a single,
> contiguous chunk of lowmem results, with all other RAM moving up
> beyond 4Gb. Of course RMRRs below the 1Mb boundary must not be
> considered here, and I think we can reasonably safely assume that
> no RMRRs will ever report ranges above 1Mb but below the host
> lowmem RAM/MMIO boundary (i.e. we can presumably rest assured
> that the lowmem chunk will always be reasonably big).

Correct - but my point is that this won't work well with your report-all
mechanism, only with the report-sel one.

Jan


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