Re: [Qemu-devel] [PATCH v4 7/8] intel_iommu: keep buggy EIM enabled in 2.7 machine type

[Radim Krčmář]

2016-10-06 18:33+0300, Michael S. Tsirkin:
> On Thu, Oct 06, 2016 at 11:51:42AM -0300, Eduardo Habkost wrote:
>> On Wed, Oct 05, 2016 at 03:06:56PM +0200, Radim Krčmář wrote:
>> > QEMU 2.7 allowed EIM even in configurations that were forbidden in the
>> > last patch because they were not working, like old KVM or userspace
>> > APIC.  In order to keep backward compatibility, we again allow guests to
>> > misbehave in non-obvious ways, and make it the default for old machine
>> > types.
>> > 
>> > A user can enable the buggy mode it with "buggy_eim=on", which is weird,
>> > but I don't know how to add a private property.
>> 
>> Properties et by compat_props are always user-visible. I believe
>> that's a feature (this way, it will be possible to let management
>> software and other tools know what exactly is behind a
>> machine-type).
> 
> There's a rule that any name beginning with x- is deemed
> experimental. See docs/qmp-spec.txt.
> It is a good idea to always use this for compat properties as
> we want to be able to drop them when we drop the old
> machine type.

"x-buggy-eim" should deter most users, thanks.

pc-0.10 seems to be the first machine type ever (2009), is there already
a plan to deprecate it?