Alexander Graf <agraf@xxxxxxx> writes: > On 07/02/2013 07:45 AM, Aneesh Kumar K.V wrote: >> From: "Aneesh Kumar K.V"<aneesh.kumar@xxxxxxxxxxxxxxxxxx> >> >> 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<aneesh.kumar@xxxxxxxxxxxxxxxxxx> > > 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>