Alexander Graf <[email protected]> writes:
> On 07/02/2013 07:45 AM, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V"<[email protected]>
>>
>> Powerpc architecture uses a hash based page table mechanism for mapping
>> virtual
>> addresses to physical address. The architecture require this hash page table
>> to
>> be physically contiguous. With KVM on Powerpc currently we use early
>> reservation
>> mechanism for allocating guest hash page table. This implies that we need to
>> reserve a big memory region to ensure we can create large number of guest
>> simultaneously with KVM on Power. Another disadvantage is that the reserved
>> memory
>> is not available to rest of the subsystems and and that implies we limit the
>> total
>> available memory in the host.
>>
>> This patch series switch the guest hash page table allocation to use
>> contiguous memory allocator.
>>
>> Signed-off-by: Aneesh Kumar K.V<[email protected]>
>
> Is CMA a mandatory option in the kernel? Or can it be optionally
> disabled? If it can be disabled, we should keep the preallocated
> fallback case around for systems that have CMA disabled.
>
CMA is not a mandatory option. But we have
config KVM_BOOK3S_64_HV
bool "KVM support for POWER7 and PPC970 using hypervisor mode in host"
depends on KVM_BOOK3S_64
select MMU_NOTIFIER
select CMA
ie, for book3s HV we select CMA and only this CMA needs is memblock
which we already support
-aneesh
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