Re: [Xen-devel] [PATCH 2/2] hvmloader: don't hard-code IO-APIC parameters

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.06.16 at 12:05, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 16/06/16 10:40, Jan Beulich wrote:
>> The IO-APIC address has variable bits determined by the PCI-to-ISA
>> bridge, and the IO-APIC version should be read from the IO-APIC. (Note
>> that there's still implicit rather than explicit agreement on the
>> IO-APIC base address between qemu and the hypervisor.)
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> The status quo is not great, and I can see why you want to improve it.
> 
> However, I think that this is not the way to do that.  It ties HVMLoader
> to the PIIX4 board in Qemu, and will break attempts to use Q35 or
> something else.  (In Q35, the IO-APIC decode address comes from Chipset
> Configuration Register, rather than ISA device config space).

hvmloader is already tied to PIIX4, and enabling Q35 will, among
other things, require hvmloader to become aware of that chipset.

Jan


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