Re: [Xen-devel] Xen 4.3 development update

[Matt Wilson <msw@xxxxxxxxxx>]

On Wed, Sep 26, 2012 at 07:59:31PM +0100, Ian Campbell wrote:
> On Wed, 2012-09-26 at 18:15 +0100, Matt Wilson wrote:
[...]
> > I brought this up in response to Jan's question as to if persistent
> > grants should be on the 4.3 release plan. With the introduction of
> > blktap3, we have a separate implementation of the protocol in a Xen
> > component. One worry I have about blktap3 is that it will lag behind
> > the in-kernel blkback implementation.
> 
> We already have multiple block backend implementations (blktap1,
> blktap2, qdisk, non-Linux dom0s), so I don't think that is a new
> concern.

For blktap2 we use blkback, so blktap2 users should be able to take
advantage of the improvements made there.

> If anything blktap3 improves things by making blktap1 + 2 obsolete, plus
> it comes with an active maintainer!

I'm not saying that blktap3 is a bad thing! It's definitely exciting.

> I think getting a working blktap3 implementation of the basic blk
> protocol for 4.3 is a big enough chunk of work in its own right, it's
> more than enough to fill someone's time for one release cycle IMHO.

Indeed, I'm impressed that it can be done. :-)

> So, I don't think implementing extensions (persistent grants, multipage
> rings etc) need to be a requirement for blktap3 in 4.3, there's always
> 4.4 and beyond. Of course if someone wants to contribute patches I'm
> sure Thanos would be very pleased ;-)

Definitely not a requirement, but a nice-to-have.

Matt

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