Re: [Qemu-devel] [RESEND PATCH v9 1/4] apic: map APIC's MMIO region at each CPU's address space

[Paolo Bonzini]

On 21/08/2015 15:54, Eduardo Habkost wrote:
> > +    if (tcg_enabled()) {
> > +        memory_region_add_subregion_overlap(cpu->cpu_as_root,
> > +                                            apic->apicbase &
> > +                                            MSR_IA32_APICBASE_BASE,
> > +                                            &apic->io_memory,
> > +                                            0x1000);
> 
> Why exactly is this necessary? If this is necessary, why don't we need
> to do this for non-TCG accelerators?

At least KVM and qtest do not support per-CPU address spaces.  I'm not
sure about Xen, it looks like it could but it would be slower.

Paolo