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Date: Fri, 01 Feb 2008 09:33:26 -0600
From: Anthony Liguori <aliguori@us.ibm.com>
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Subject: [Qemu-devel] Re: [kvm-devel] [PATCH 1/6] Use correct types to
	enable > 2G support
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To: Avi Kivity <avi@qumranet.com>
Cc: kvm-devel@lists.sourceforge.net, qemu-devel@nongnu.org, Paul Brook <paul@codesourcery.com>

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