Re: [Qemu-devel] [PATCH 4/6] i386: Infrastructure for versioned CPU models

[Eduardo Habkost <ehabkost@redhat.com>]

On Tue, Jun 25, 2019 at 10:32:01AM +0100, Dr. David Alan Gilbert wrote:
> * Eduardo Habkost (ehabkost@redhat.com) wrote:
> > Base code for versioned CPU models.  This will register a "-4.1"
> > version of all existing CPU models, and make the unversioned CPU
> > models be an alias for the -4.1 versions on the pc-*-4.1 machine
> > types.
> > 
> > On older machine types, the unversioned CPU models will keep the
> > old behavior.  This way, management software can use old machine
> > types while resolving aliases if compatibility with older QEMU
> > versions is required.
> > 
> > Using "-machine none", the unversioned CPU models will be aliases
> > to the latest CPU model version.
> > 
> > Includes a test case to ensure that:
> > old machine types won't report any alias to versioned CPU models;
> > "pc-*-4.1" will return aliases to -4.1 CPU models;
> > and "-machine none" will report aliases to some versioned CPU model.
> > 
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> 
> What happens when we add the next new CPU model?  So say in 4.2 we add
> a new CPU, does that default to being newcpu-4.2 ?

We can choose between providing old versions of the CPU model
retroactively ("NewModel-4.1" and "NewModel-4.2"), or providing
only "NewModel-4.2".

The question is: if we provide only "NewModel-4.2", what should
be the behavior of "-machine pc-i440fx-4.1 -cpu NewModel"?

-- 
Eduardo