Re: [Qemu-devel] per-machine vs per-qemu-version compat_props macros (was Re: acpi:ich9: add memory hotplug handling)

[Eduardo Habkost]

On Tue, Jun 24, 2014 at 05:47:53PM +0100, Peter Maydell wrote:
> On 24 June 2014 17:44, Eduardo Habkost <address@hidden> wrote:
> > (I would go even further and say that no compat_props bit need to be
> > specific to a machine-type family, and they are simply tied to the code
> > included in a QEMU version. So every PC_COMPAT_* bit could go to a
> > common QEMU_COMPAT_<version> macro, that could be reusable by all
> > machine-types, and there's no need PC-specific compat macros.)
> 
> What if different machines in a particular release had the
> property set to different defaults?

I never saw that happen, and I don't think it is even likely: default
values set in instance_init, and compat_props are applied just after
instance_init, before object_new() returns. So a machine-type would need
to find a way to change fields after instance_init but before
compat_props are applied.

Anyway, if a machine-type really needs that, it can still have its own
set of compat macros to implement machine-type-specific compat_props. My
point is that there's no need for that on the PC code today.

-- 
Eduardo