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

Carsten Otte
2007-10-26T11:45:08Z

Avi Kivity wrote:
> Why aren't memory slots common too? Only their number is different,
> while the implementation is the same.
Your approach makes the meaning of memory slot somewhat useless on
s390, if that one may be sparse and may be result of different
allocations: On x86, there has to be one memory slot per allocation,
versus on s390 there has to be exactly one memory slot with multiple
allocations behind.

For userspace that means, with your approach it has to do total
different memory setup for different archs _if_ it wants to use
multiple allocations and/or sparse:
- on x86 it does allocations to random userspace address, and
registers each of them as memory slot
- on s390 it does allocations to a specific address layout similar to
the guest, and registers only one memory slot for the whole thing

With Izik's approach however, this is transparent to userspace: it has
multiple memory slots, one per allocation. Regardless of the CPU
architecture.