Re: Xen 4.4 development update

[George Dunlap <george.dunlap@eu.citrix.com>]

On 19/08/13 13:08, Pasi Kärkkäinen wrote:
> On Mon, Aug 19, 2013 at 12:38:16PM +0100, George Dunlap wrote:
>> * However, blktap is unmaintained.  Unless someone steps up to add
>> the functionality (which is not recommended as it would probably te
>> a waste of effort), it will continue to require a modprobe. On newer
>> systems, without blktap, the modprobe will be harmless.  So for
>> blktap, the modprobe will have to remain for the forseeable future.
>>
> What I've been wondering.. XenServer is shipping with and using blktap,
> so there must be someone maintaining blktap at Citrix?
> I also understand blktap is on the way out and will be replaced with qdisc in the future..

As I understand it, XenServer is using a private fork of blktap2, with 
significant changes.  Since blktap2 as a whole can't be upstreamed into 
the mainline kernel, I think the feeling was that there wasn't any point 
in trying to upstream the local changes to the "classic" kernel.  
Blktap3 was meant to be the mainline-friendly version of blktap, but as 
you say, work on it has halted and the plan at the moment, I'm told is 
to look into qdisk, since it uses a similar technology, but gives access 
to work from other communities as well (Ceph, for example).

Thanos, correct me if I've made a mistake somewhere...

  -George