Re: [Xen-devel] [PATCH] x86: use 'dom0_mem' to limit the number

To:	Jan Beulich <JBeulich@xxxxxxxxxx>, David Vrabel <david.vrabel@xxxxxxxxxx>
Subject:	Re: [Xen-devel] [PATCH] x86: use 'dom0_mem' to limit the number of pages for dom0
From:	Keir Fraser <keir.xen@xxxxxxxxx>
Date:	Tue, 23 Aug 2011 13:03:10 +0100
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On 23/08/2011 10:41, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:

>>> Besides that the assignment needs to be saturating, as struct domain's
>>> max_pages member is only "unsigned int", whereas the local variables
>>> are all "unsigned long". So in the end this should really be an equivalent
>>> of
>>> 
>>>     d->max_pages = min(max_pages, UINT_MAX);
>> 
>> We should make d->max_pages a ulong or u64.
> 
> I'd rather not, as for now there's no good reason for this to be a
> 64-bit variable (as we can't get even close to the 16Tb it would
> take to overflow this). But then again I expect you to say that
> the few extra REX prefixes don't matter all that much...

Ha, you'd be right! :-)

I'll leave it to David to champion his patch. I'll note I added it for 4.1.2
as well, if we decide there is a better way we will need to change it there
in advance of that release, and preferably -rc1 as well.

 -- Keir



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Re: [Xen-devel] [PATCH] x86: use 'dom0_mem' to limit the number of pages