Re: [RFC PATCH kernel] vfio-pci: Allow write combining

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Oct 16, 2017 at 04:54:08PM +1100, Alexey Kardashevskiy wrote:
> On 12/10/17 02:35, Benjamin Herrenschmidt wrote:
> > On Wed, 2017-10-11 at 13:56 +1100, Alexey Kardashevskiy wrote:
> >> Oopsie. This is because I overlooked it. Others do not use it. So I do need
> >> a file. But in the current scheme where all BARs share one fd - it won't
> >> work - I simply cannot allow WC on non-prefetchable BARs :-/
> > 
> > This is an oversight in the design of VFIO-PCI, it should have a way to
> > specify write combine, either implicitely via such an arch hook, or
> > explicitely via an ioctl prior to mapping the BARs for example.
> > 
> > Alex, what do you reckon is the best approach here ?
> 
> /me wonders if it is yet another issue for the dead issues bucket, just
> like the msix mapping one :)

Maybe.  Alexey, maybe you can make up a list of things that we (me,
you, BenH) need to discuss with Alex W at KVM Forum?

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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