Re: [Qemu-devel] [PATCH 0/4] Introduce common QEMU_COMPAT_* macros

[Eduardo Habkost]

On Wed, Jun 25, 2014 at 10:34:24AM +0300, Michael S. Tsirkin wrote:
> On Tue, Jun 24, 2014 at 03:02:00PM -0300, Eduardo Habkost wrote:
> > This series is an attempt to make the compat_props lists from the PC code
> > reusable by other machine-types. All the compat bits that are on those 
> > lists are
> > not tied to a specific machine-type, but instead to the device code that was
> > present on a given QEMU version.
> > 
> > The last patch is a proposal to simply eliminate the PC-specific compat 
> > props
> > macros, because we don't really need them today. All compat properties we 
> > have
> > can be on global QEMU-version-specific lists, because PC-specific 
> > properties are
> > not going to affect other machine-types anyway.
> 
> So global properties are really not so special.
> They just need to be specified with <X>.<Y>=<Z> syntax.
> Can we just make them properties of a QEMU object?
> 
> I would like to make it possible for management to
> ask "what's the default value for that property with that
> machine type".
> 
> Need to add API to make this painless, with not more lines of code
> than currently.
> 

We don't even have an API for asking for class property info (with no
machine-type-specific data) yet. I keep asking if we are going to move
towards some day. But the current plan is unclear to me, and the only
available method today seems to be "just create an object and ask for
its properties" (the same seems to be necessary even for listing the
available property _names_).

There has been some discussion about it at:
http://marc.info/?l=qemu-devel&m=139170340408156
but the conclusion was unclear.

-- 
Eduardo