Re: [qemu-s390x] [PATCH/RFC] s390x: split memory into 4TB chunks

[Paolo Bonzini]

On 06/12/2017 13:15, Christian Borntraeger wrote:
>> a) bumping up KVM_MEM_MAX_NR_PAGES makes sense.
> The original limitation comes from the fact that this define is used to limit
> the number of bits in the dirty bitmap as some architectures do not provide
> bitops beyond 2^32.
> 
>> b) as I said, transparently handle it in kvm slot handling code.
> adding Paolo to check what he thinks.

It's a bit of a first-world problem, :) and working around it in QEMU
makes is easy enough that it's okay in my opinion.

Bumping up KVM_MEM_MAX_NR_PAGES if the bitops allows it should be a good
idea too, but it requires auditing the code for overflows and truncations.

Paolo