Re: [kvm-ppc-devel] RFC/patch portability: split kvm_vm_ioctl v2

Avi Kivity
2007-10-28T09:57:59Z

Zhang, Xiantao wrote:
> Avi Kivity wrote:
>
>> Hollis Blanchard wrote:
>>
>>> On Fri, 2007-10-26 at 10:21 +0200, Carsten Otte wrote:
>>>
>>>
>>>> As Xiantao pointed out, x86 and ia64 can share the same memory setup
>>>> code. But s390 and ppc don't. Therefore, I vote for putting it into
>>>> x86 for now, and come up with an approach to share between x86 and
>>>> ia64 later on.
>>>>
>>>>
>>> The only thing in the current ioctl code that doesn't make sense for
>>> PowerPC is the rmap stuff. The concept of "slots" as memory extents
>>> is just fine.
>>>
>>> Originally, I think the only question was how to register the slots
>>> on the kernel side. Today that is done with separate
>>> KVM_SET_USER_MEMORY_REGION ioctls, one for each guest physical
>>> region.
>>>
>>>
>> Wht about aliases? Aliases allow you go have two different physical
>> addresses for the same page. This is useful for mapping the
>> framebuffer on x86 (both at the pci region and at 0xa0000, the
>> traditional ISA location).
>>
>> Are they useful for ia64?
>>
>
> Sure, it also should benefit IA64 side :)
>

Actually, thinking about it, regular memory slots support this too.
Simply create a new memory slot to that memory. So aliases can be x86
specific (for compatibility reasons).

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