Re: [Xen-devel] [PATCH 4 of 5] blkif.h: Document the RedHat and Citrix blkif multi-page ring extensions

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 03.02.12 at 16:19, Justin Gibbs <justing@xxxxxxxxxxxxxxxx> wrote:
> However,
> if this is the rule, both types of "max ring size" values are "in effect" 
> even if a back-end
> does not provide them both.  So how do you resolve the conflict?  A fully 
> interoperable
> front should allocate the largest possible ring and advertise that size 
> through both
> mechanisms in a fully consistent manner. That's what I was trying to 
> indicate by
> writing the spec this way.

Hmm, I would think a fully compatible frontend should bail (revert to
single page ring) on inconsistent max-ring-pages and
max-ring-page-order, if both are provided by the backend. The limit
for ring-pages should always be max-ring-pages, while the one for
ring-page-order should always be max-ring-page-order. Any mixture
is an error, unless both values are consistent with one another.

Jan


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