Re: [Qemu-devel] [RFC 01/18] pc: create "PC" device class

[Eduardo Habkost]

On Thu, Oct 04, 2012 at 12:42:23PM -0500, Anthony Liguori wrote:
> Eduardo Habkost <address@hidden> writes:
> 
> > On Thu, Oct 04, 2012 at 10:10:16AM -0500, Anthony Liguori wrote:
> >> Eduardo Habkost <address@hidden> writes:
> >> 
> >> > On Thu, Oct 04, 2012 at 09:28:13AM -0500, Anthony Liguori wrote:
> >> >> Paolo Bonzini <address@hidden> writes:
> >> >> 
> >> >> > Il 04/10/2012 15:46, Anthony Liguori ha scritto:
> >> >> >>> > +typedef struct PC {
> >> >> >>> > +    DeviceState parent_obj;
> >> >> >>> > +} PC;
> >> >> >> So the general problem with this approach is that it strays from
> >> >> >> modeling hardware.
> >> >> >
> >> >> > It doesn't really; it's a motherboard object, there's no reason why
> >> >> > /machine shouldn't be a Device itself, with a few objects (CPUs, the
> >> >> > i440FX, the IOAPIC, and of course the peripherals) hanging off it.
> >> >> 
> >> >> Okay, but modeling a motherboard is different than creating a "PC"
> >> >> object and throwing in the kitchen skink.
> >> >> 
> >> >> And I'm not sure that going top-down is the best strategy.  I think
> >> >> going bottom up makes more sense (starting with modeling Super IO chip).
> >> >> 
> >> >
> >> > So, would you be OK with this implementation if the class were named
> >> > "Motherboard", "set-of-CPU-sockets", or something like that?
> >> 
> >> I would, but you're mixing up modeling with bug fixing.
> >> 
> >> There's a very easy way to achieve your goal without dramatic
> >> remodeling.
> >> 
> >> Just assign APIC ids during CPU creation and make contiguous_apic_ids a
> >> parameter of pc_init1.
> >> 
> >> You don't need to worry about CPU hotplug.  It doesn't exist in qemu.git
> >> and is broken in qemu-kvm.git.
> >
> > With or without CPU hotplug, the max_cpus variable already exists, and I
> > want to avoid breaking code that's already using it, and adding Yet
> > Another problem to be fixed by whoever is going to make CPU hotplug
> > work.
> 
> Sorry, what does max_cpus have to do with apic ids??

See patch 15/18.

-- 
Eduardo