Re: [Qemu-devel] [PATCH] spapr: Make machine naming conventions closer to those for PC

[Markus Armbruster]

David Gibson <address@hidden> writes:

> As of qemu-2.1, spapr/pseries, has a set of versioned machine classes to
> represent the machine type as it appeared to the guest in different qemu
> versions.  This allows for safe migration of guests between current and
> future qemu versions.
>
> In PC, however, the default plain "pc" machine type is just an alias for
> the most recent versioned machine type.  In sPAPR at the moment, it names
> the base machine class from which the versioned types are derived.
>
> The PC approach is preferable; it makes it clearer which explicit version
> is the current one.  Additionally updating the "current" machine as the
> base class makes it even more likely than otherwise to incorrectly alter
> the versioned machines' behaviour when updating the current machine.
>
> Therefore this patch changes sPAPR to the PC approach - the base class
> becomes abstract, and plain "pseries" becomes an alias for the most
> recent versioned machine class.
>
> Signed-off-by: David Gibson <address@hidden>
> ---
>  hw/ppc/spapr.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index d01978f..2785dbc 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1583,7 +1583,6 @@ static void spapr_machine_class_init(ObjectClass *oc, 
> void *data)
>  
>      mc->name = "pseries";
>      mc->desc = "pSeries Logical Partition (PAPR compliant)";
> -    mc->is_default = 1;
>      mc->init = ppc_spapr_init;
>      mc->reset = ppc_spapr_reset;
>      mc->block_default_type = IF_SCSI;

I suspect many of these assignments are actually overwritten by the
derived machine types' class init function.  Without that, mc->name =
"pseries" would clash with the mc->alias = "pseries" below, wouldn't i?

Care to trim the redundant assignments?

> @@ -1598,6 +1597,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
> void *data)
>  static const TypeInfo spapr_machine_info = {
>      .name          = TYPE_SPAPR_MACHINE,
>      .parent        = TYPE_MACHINE,
> +    .abstract      = true,
>      .instance_size = sizeof(sPAPRMachineState),
>      .instance_init = spapr_machine_initfn,
>      .class_init    = spapr_machine_class_init,
> @@ -1613,7 +1613,8 @@ static void spapr_machine_2_1_class_init(ObjectClass 
> *oc, void *data)
>  
>      mc->name = "pseries-2.1";
>      mc->desc = "pSeries Logical Partition (PAPR compliant) v2.1";
> -    mc->is_default = 0;
> +    mc->alias = "pseries";
> +    mc->is_default = 1;
>  }
>  
>  static const TypeInfo spapr_machine_2_1_info = {