[Qemu-devel] Re: [kvm-devel] [PATCH 1/6] Use correct types to enable > 2G support

[Anthony Liguori]

Avi Kivity wrote:
> Anthony Liguori wrote:
>   
> > I think I'll change this too into a single qemu_ram_alloc.  That will 
> > fix the bug with KVM when using -kernel and large memory anyway :-)
> >     
>
> Won't that cause all of the memory in the hole to be wasted?
>
> You could munmap() it, but it's hardly elegant.
>   

It only gets wasted if it gets faulted in.  Any it won't get faulted in, 
so it won't increase the RSS size.  We could madvise(MADV_DONTNEED) just 
to ensure that it's not occupying swap space if you were really paranoid 
about it.  I don't think munmap()'ing malloc()'d memory is a very good 
idea.  glibc may freak out.

The alternative is to change all the places that assume phys_ram_base + 
PA which I don't like very much.

Regards,

Anthony Liguori