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

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Carsten Otte wrote:
> 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.

No, a memory slot can span multiple backing stores.  But it must be 
contiguous in both the host userspace and guest physical address spaces.

>
> 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.

You can do this with the current memory slots as well.  Although I'm 
feeling that I misunderstood Izik's idea.  I'll go talk to him.

-- 
error compiling committee.c: too many arguments to function


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