Re: [Xen-devel] [Xen-users] Future of xend and xl (Was: Re: VGA passthough still not working)

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-01-25 at 19:43 +0000, Florian Heigl wrote:
> How about if we assemble a list of Xen features in xm/xend and those
> that you have implemented in xl. Right now it's just guesswork and a
> lot double effort since one doesn't just have to track which parts are
> gone, but we even have to constantly read all threads on the lists to
> find out if a feature is suddenly coming back or being deprecated.

I agree that a list of features which xl supports would be a useful
thing to have. I have just made a start on updating
http://wiki.xen.org/wiki/XL with such a list (as well as some more
highlevel blurb). Further contributions welcomed ;-)

However I don't think it will be feasible or useful to construct a list
of all the features of xm/xend, since there is no one around who knows
what they all are. Even if we did we would have to know which of them
were actually useful to users (some are obvious) and which would be a
wasted effort (which could be better spent elsewhere) to reimplement.

Therefore we chose to go straight to the horses mouth and ask users to
try xl and report which features that they actually use and require are
missing. IIRC we have been doing this since the early 4.1 rc's, have
continued to do so throughout the 4.2 development cycle and will no
doubt continue to to do so through the 4.3 release cycle, if not beyond.

Perhaps we need to be a bit more vocal to our users about the "report
missing features which you require" part of this.

I should note that we are not aiming for 100% feature parity between xl
and xend. As I discussed above some features of xend are unused and
there are others (the main one being managed domains) which we have
explicitly decided that xl will not support.

As with all Open Source software there is also an element of scratching
one's own itch here. We are trying to respond to user requests and as
the xl feature-set rounds out we will no doubt be considering more and
more "minority" features but there are only so many of us and only so
many hours in the day. So ultimately if you need or want a feature then
we are more than happy to accept new features which people feel are
valuable and to help with the work that might be necessary.

[...]

> But maybe we can have a somewhat reliable roadmap where one can see xm
> will be kicked in 4.4 *and* we're planning to have the following 1234
> features supported by then.
> That way interested parties have a chance to put ressources into
> getting missing features "back in" 

>From this point of view you should assume that xend has already gone and
put resources into this _now_, there is no reason to wait for some
arbitrary deadline.

Once we are satisfied that we have covered the necessary and desirable
use cases will we actually remove xend. It is very likely that this will
happen soon.

Even though xend is still in tree it is unmaintained and deprecated and
we strongly recommend that users switch to xl and give us feedback where
features are found to be lacking.

In contrast xl was production ready in 4.1 and will continue to gain
features in 4.2 and beyond.

[...]

> p.s.: I am aware I will have to make up for this mail in beer once
> there is an opportunity.

I will certainly take you up on that ;-)



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