[libvirt] [PATCH] Introduce a -libvirt-caps flag as a stop-gap

[Daniel Veillard]

On Tue, Jul 27, 2010 at 10:55:03AM -0500, Anthony Liguori wrote:
> Today libvirt parses -help output to attempt to enumerate capabilities.  This
> is very broken and has led to multiple failures.  Since libvirt is an important
> management interface to QEMU, we need to do a better job giving them the ability
> to detect what a QEMU executable supports.  Right now, we keep fixing up help
> output to appease it's parsing code but this is undesirable.
> 
> The Right Solution is to introduce a robust capabilities advertisement that
> enumerates every feature we have.  As with most Right Solutions, we don't have
> mergable code today and it's unclear that we'll get there by the next release.
> 
> This patch introduces an incremental solution of just spitting out the handful
> of capabilities libvirt is probing for today.  This interface will need to
> remain forever but can stop being updated once we have a Right Solution.

  Unfortunately, that doesn't sounds like a solution to me either,
we need the capabilities support in the long term, and we will need
to keep the help output parsing code for legacy support. That mean
adding support for a third way, just for one or 2 release of QEmu.
  So even if this was sufficient for libvirt as a temporary measure
I'm afraid the burden and extra code maintainance/testing etc. is not
worth it. We can live with help output parsing until the correct
solution is finalized, and it's IMHO better than supporting forever
a temporary half cooked solution both in libvirt and in QEmu.

  thanks,

Daniel

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