Re: [Qemu-devel] [PATCH v3] hw/i386: Deprecate the machines pc-0.10 to pc-1.2

[Thomas Huth]

On 12.07.2017 17:04, Daniel P. Berrange wrote:
> On Wed, Jul 12, 2017 at 10:22:33AM +0200, Thomas Huth wrote:
>> We don't want to carry along old machine types forever. If we are able to
>> remove the pc machines up to 0.13 one day for example, this would allow
>> us to eventually kill the code for rombar=0 (i.e. where QEMU copies ROM
>> BARs directly to low memory). Everything up to pc-1.2 is also known to
>> have issues with migration.  So let's start with a deprecation message
>> for the old machine types so that the (hopefully) few users of these old
>> systems start switching over to newer machine types instead.
> 
> I think we must document & agree on our support policy for machine
> types, before we start marking them as deprecated. eg please consider
> the following document before accepting this deprecation patch:
> 
>  https://lists.gnu.org/archive/html/qemu-devel/2017-07/msg00652.html
> 
> Note in that proposal there, I say we do *not* go through trouble of
> explicitly marking machines as deprecated. We just document upfront
> the intended lifecycle and then delete them when it is done.
> 
> Just use deprecation warnings for things where there is no predictable
> lifecycle upfront.

I'm still not 100% sure whether that auto-deprecation of machine types
is such a good idea ... since we might need to maintain machines in
downstream a little bit longer than specified there, it might be better
to rather deprecate them manually from time to time.

Anyway, concerning my patch - I'll stop here and won't send another
version. There is too much bikeshed painting going on in this area for
my taste, and since I'm rather a powerpc / s390x guy, I'm also fine if
the pc-0.x machines stay around forever. If somebody else wants to push
this topic instead, feel free to do so.

 Thomas