Re: [Qemu-devel] [PATCH 2/7] Convert pc cpu to qdev

[Anthony Liguori]

On 02/16/2012 06:54 AM, Jan Kiszka wrote:
> On 2012-02-16 13:51, Anthony Liguori wrote:
> > On 02/16/2012 06:01 AM, Jan Kiszka wrote:
> > > On 2012-02-16 00:16, Igor Mammedov wrote:
> > > > +static ICCBusDeviceInfo cpu_device_info = {
> > > > +    .qdev.name = "cpu-pc",
> > > > +    .qdev.size = sizeof(CPUPC),
> > > > +    .qdev.reset = cpu_device_reset,
> > > > +    .init = cpu_device_init,
> > > > +    .qdev.props = (Property[]) {
> > > > +        DEFINE_PROP_STRING("model", CPUPC, model),
> > >
> > > And how do you pass in feature flags? Or the core layout? Basically both
> > > -cpu and -smp need to be expressible via multiple "-device cpu-x86,xxx"
> > > (not "pc") commands.
> >
> > The approach that I'd recommend is:
> >
> > 1) convert CPU_COMMON_STATE to a structure named CPUCommonState, query/replace
> > all references to members of CPU_COMMON_STATE appropriately.
> >
> > 2) convert as many users of CPUState to CPUCommonState as possible.
> >
> > 3) make CPUCommonState a base class, move it to the front of the structure, and
> > attempt to measure the impact to TCG.
> >
> > 4) if (3) is significant, special case things in QOM
> >
> > 5) make target specific code use target specific CPUState typename
> >
> > 6) eliminate #define CPUState
> >
> > 7) make on-processor devices (like lapic) children of target specific CPUState
> >
> > 8) express target specific flags/features via QOM properties
> >
> > 9) make machine expose target specific CPUState links that can be set by the 
> > user.
>
> Also, I'm wondering what names those CPUs should have. I think we should
> expose model names as device names and avoid a "model" property.

Yeah, I think we want a CPUX86State and then a bunch of subclasses defined by 
that.

By making use of the class_data field, we can register classes based on 
combinations of feature flags.  So for instance:

static TypeInfo opteron_g2 = {
  .name = "cpu-opteron-g2",
  .parent = TYPE_CPU_X86",
  .class_init = cpu_x86_generic_class_init,
  .class_data = (CPUX86Definition[]){
      .level = 5,
      .vendor = "AuthenticAMD",
      .family = 15,
      .model = 6,
      .stepping = 1,
      .feature_edx = "sse2 sse fxsr mmx pat cmov pge sep apic cx8 mce pae msr 
tsc pse de fpu   mtrr clflush mca pse36",
      ...
   },
};

And obviously, we can still using the existing cpudef directive to generate 
types.

Regards,

Anthony Liguori

> Jan