Re: [Xen-devel] xend deprecation

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 05/09/13 11:18, Fabio Fantoni wrote:
> Il 04/09/2013 18:33, Konrad Rzeszutek Wilk ha scritto:
> > On Wed, Sep 04, 2013 at 04:34:30PM +0100, Ian Campbell wrote:
> > > On Wed, 2013-09-04 at 16:18 +0100, George Dunlap wrote:
> > > > On Wed, Sep 4, 2013 at 3:04 PM, Konrad Rzeszutek Wilk
> > > > <konrad.wilk@xxxxxxxxxx> wrote:
> > > > > On Wed, Sep 04, 2013 at 08:29:07AM +0100, Ian Campbell wrote:
> > > > > > On Tue, 2013-09-03 at 23:06 -0700, Matt Wilson wrote:
> > > > > > > On Tue, Sep 03, 2013 at 09:03:46AM +0100, Ian Campbell wrote:
> > > > > > > > On Mon, 2013-09-02 at 13:32 -0700, Matt Wilson wrote:
> > > > > > > > > Live migration between a system running xend to a system that 
> > > > > > > > > doesn't
> > > > > > > > > support xend would be a nice-to-have. That probably means some 
> > > > > > > > > support
> > > > > > > > > for SXP parsing either in libxl or in some compatibility tool.
> > > > > > > > This already works by using xl on the source side, e.g. a guest 
> > > > > > > > started
> > > > > > > > with xend on 4.1 can be migrated with 4.1's xl to 4.2.
> > > > > > > >
> > > > > > > > http://lists.xen.org/archives/html/xen-devel/2012-08/msg02191.html
> > > > > > > xl doesn't run everywhere that we need it to.
> > > > > > Details please, or we aren't going to be able to even think about 
> > > > > > how to
> > > > > > solve this for you.
> > > > > >
> > > > > > BTW You can also do a xend migration to e.g. 4.2 (using the xend 
> > > > > > whichis
> > > > > > in 4.2) and the use 4.2's xl to do a localhost migrate or a second
> > > > > > remote migrate to another 4.2 system.
> > > > > >
> > > > > > xend's deprecation has been on the cards, and widely known, for 
> > > > > > several
> > > > > > releases now. It is time to quit stalling and start moving. I 
> > > > > > intend to
> > > > > > post a patch deleting it as soon as 4.4 is out the door.
> > > > > And I think I might have to lobby hard against removing it.
> > > If by lobby you mean "step up to maintain" then please do.
> > I can surely do that, but I would prefer to have the issues fixed.
> >
> > > > > There are issues that are stopping us from using it:
> > > > >
> > > > >   - No status in xl list -l when only dom0 is present.
> > > xl list -l produces a tonne of output here when only dom0 is present.
> > >
> > > > >   - 'xl list -l' says 'Domain name must be specified' even though 
> > > > > the '-l'
> > > > >     is for 'Output all VM details'
> > > Not here it doesn't.
> > >
> > > IIRC this was a bug in 4.1 or 4.2 timescales, which is now fixed.
> > Odd, I am running Xen 4.3. Hm, time to rebase.
> >
> > > > >   - xl list -l for PV guest has bug: itâs not formated 
> > > > > S-expression text.
> > > This is a feature not a bug. However you can request an sxp
> > > compatibility mode (I forget how, check the manpage). Note that this
> > > doesn't include new features, so you would be advised to make plans to
> > > switch to consuming the json variant.
> > >
> > > > >   - No console in xl list -l, so can't get  tty console port.
> > > That one should be easily fixable
> > >
> > > > >   - xl uses SSH for migration. We need SSL daemon or socat like 
> > > > > xend has.
> > > You can provide any tool you like to run instead of ssh, including an
> > > ssl daemon/client or socat. See the manpage.
> > Right, except that the socat part does not work as the 'ssh' arguments
> > are encoded in the code. I am not saying that these are 
> > 'earth-shattering hard
> > to fix' it just that they should be done before Xend is gone.
> >
> > > > > Those should be fixed at some point :-) Problem is that other things
> > > > > keep on popping up on the radar and hence we end up using xend.
> > > > Uum, when were you going to report these?  A lot of us were under the
> > > > impression that xl behaved sufficiently like xend for anyone who
> > > > cared.
> > > >
> > > > Maybe we should make an announcement (on blog, xen-users, xen-devel,
> > > > and xen-announce) that there has been a proposal to make 4.4 the last
> > > > release with xend, and so it's important to report all bugs / missing
> > > > features of xl so we can get them fixed by the 4.4 release?
> I think is a good idea, if will not removed on xen 4.4 at least 
> disabled it by default to get more visible the new xl to the users and 
> get more feedback.
> About very small thing present in xend and not in xl not reported for 
> now is the autocompletion name of domU in commandsmissed.
> I think is good do a similar thing with qemu traditional with 
> deprecation and massive comunication of a certain deadline.
qemu is a bit different than xend: it is entirely possible to migrate a 
VM started with xend to a system using only xl.  I don't think the same 
is true for qemu; so we will probably be keeping qemu-traditional around 
for some time after qemu-xen has reached feature parity (which it still 
has yet to do).
 -George

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