Re: [Xen-devel] [PATCH] xl: Special case tap/aio for disk validation

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Thu, 2011-01-27 at 20:14 +0000, Kamala Narasimhan wrote:
> > While fixing the disk parsing is critical for 4.1, I am not sure if we
> > can deprecate the current syntax for 4.1 as well.
> > We should keep in mind that xend is still using the other syntax and it
> > is still present in-tree, so if we really want to deprecate it we need
> > to fix xend too. 
> 
> By deprecating I didn't mean we would remove the functionality and
> introduce inconsistency between xend and xl in terms of usage.  I
> wasn't sure if we should stop with documenting the fact that it is
> deprecated or also display a warning message (in libxl) to that
> effect.  I would go with a warning also unless someone disapproves.

When I originally said "deprecate" I really meant "plan to deprecate",
i.e. accept the new and old syntax now and intend to deprecate the old
syntax e.g. in 4.2.

WRT xend compatibility, I think the goal that a xend/xm configuration
file can be fed to xl without modification is a worthy one and obviously
aids in the transition etc.

The opposite goal (that an xl configuration file can be fed directly to
xm) is not so obviously worthwhile.

I don't think we should be hobbling the evolution and ongoing use of the
xl configuration file syntax (or indeed the (lib)xl functionality)
simply to keep xend happy, in just the same way as we currently don't
insist that every feature added to (lib)xl also gets added to xend.

I guess what I mean is that if people use xl specific syntax/options in
their configuration files then they should not expect things to Just
Work if they go back to xend.

Ian.


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