Re: [Xen-devel] revert commit e4fd0475 ("hvmloader: always include HPET table")

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

Il 03/07/2013 14:03, Jan Beulich ha scritto:
>>>> On 03.07.13 at 13:45, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>> Il 03/07/2013 13:43, Jan Beulich ha scritto:
>>> Windows SVVP tests requiring a HPET ACPI table is in my opinion
>>> not a valid reason to always expose that table - respective tests
>>> should be run with "hpet=1" in the guest config file.
>>>
>>> The problem here is that at least with qemu-traditional, which
>>> by default doesn't appear to emulate a HPET,
>>
>> Isn't the HPET emulated in the hypervisor anyway?
> 
> No:
> 
> static int hpet_range(struct vcpu *v, unsigned long addr)
> {
>     return (v->domain->arch.hvm_domain.params[HVM_PARAM_HPET_ENABLED] &&
>             (addr >= HPET_BASE_ADDRESS) &&
>             (addr < (HPET_BASE_ADDRESS + HPET_MMAP_SIZE)));
> }

Ah, I meant with hpet=1.  Of course if hpet=0 qemu shouldn't emulate it
or should be told not to emulate it.

The idea of the patch was that anyway Device(HPET) is disabled in the
ACPI table if the hpet is disabled.  But if old Linux guests cannot cope
with this, too bad...

Paolo

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