Re: [Xen-devel] Xen blktap driver for Ceph RBD : Anybody wants to test ? :p

From: George Dunlap <george.dunlap@eu.citrix.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: "Sylvain Munaut" <s.munaut@whatever-company.com>,
	"Pasi Kärkkäinen" <pasik@iki.fi>,
	"ceph-devel@vger.kernel.org" <ceph-devel@vger.kernel.org>,
	"James Harper" <james.harper@bendigoit.com.au>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
	"Stefano Stabellini" <stefano.stabellini@eu.citrix.com>,
	"Roger Pau Monne" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] Xen blktap driver for Ceph RBD : Anybody wants to test ? :p
Date: Mon, 5 Aug 2013 16:20:20 +0100	[thread overview]
Message-ID: <51FFC2B4.6010100@eu.citrix.com> (raw)
In-Reply-To: <20130805151814.GG27858@zion.uk.xensource.com>

On 05/08/13 16:18, Wei Liu wrote:
> On Mon, Aug 05, 2013 at 03:04:47PM +0100, George Dunlap wrote:
>> On 05/08/13 14:55, Sylvain Munaut wrote:
>>> Hi George,
>>>
>>>
>>>> Yes; qemu knows how to be a Xen PV block back-end.
>>> Very interesting. Is there documentation about this somewhere ?
>>> I had a look some time ago and it was really not very clear.
>>>
>>> Things like what Xen version support this. And with which features (
>>> indirect descriptors, persistent grants, discard, flush, ...) and/or
>>> which limitation.
>> I don't think this is documented anywhere; you'll need to ask the
>> experts.  Stefano? Roger? Wei?
>>
> These are Linux features not Xen ones AFAICT. In theory they are not
> bound to specific Xen versions.
>
> For the network part I don't think new features depend on any specific
> hypercall. However for block Roger and Stefano seem to introduce
> new hypercalls for certain features (I might be wrong though).

We're talking about qemu; so the toolstack needs to know how to set up 
qdisk, and I think qdisk would need to be programmed to use, for 
example, persistent grants, yes?

  -G