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Re: [Xen-devel] Driver domains and hotplug scripts, redux

2012/1/17 Ian Campbell <Ian.Campbell@xxxxxxxxxx>:
> On Tue, 2012-01-17 at 09:40 +0000, Roger Pau Monnà wrote:
>> 2012/1/17 Ian Campbell <Ian.Campbell@xxxxxxxxxx>:
>> > However xend should not be transition to this new scheme but should
>> > continue to use its existing scripts in the current manner.
>> >
>> > There was a conversation last year[0] about how a toolstack could
>> > opt-in/out of the use of the hotplug scripts. We decided that toolstacks
>> > should have to opt into the use of these scripts, by touching a stamp
>> > file.
>> >
>> > Although this wasn't implemented yet (unless I missed it) I guess the
>> > same scheme would apply to this work if that sort of thing turns out to
>> > be necessary.
>> Sorry for replying so many times, this is a big maybe, and possibly
>> it's too drastic, but after this changes xl and xend will not be
>> compatible anymore, so why don't we disable xend by default, and only
>> build xl?
> I don't think they are compatible now, are they? I've certainly seen odd
> behaviour when using xl with xend (accidentally) running, usually xend
> reaps the domain I've just started...
> I'm all for disabling the build of xend by default but I had assumed
> that others would think 4.2 was rather an aggressive timeline for that.
>> When the new configure script is in, it will be trivial to select if
>> you want xl or xend, and only install one of those. Adding the option
>> --enable-xend should disable xl and only build and install xend
>> (printing a very big warning that xend is deprecated).
> I don't think --enable-xend should ever disable xl (or vice versa). Many
> folks (e.g. distros) will want to build both, perhaps to package them in
> two different binary packages, but certainly to offer their users the
> choice, at least for the time being.

My main concern with this is that xend and xl will start to use
different udev rules (well, xend will continue to use the existing
ones, while xl will only use a subset of those). So we have to decide
which udev rules file to install, because we can't have both installed
at the same time.

Another option is to install xl udev rules by default, and make xend
move it's own rules in the init script. Since xl doesn't use a daemon,
xl should always check if xend is running before doing anything and
fail if xend is found.

>> > Ian.
>> >
>> > [0] http://lists.xen.org/archives/html/xen-devel/2011-06/msg00952.html
>> >

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