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From: Keir Fraser <keir@xensource.com>
To: Jan Beulich <jbeulich@novell.com>, Susan Krysan <KRYSANS@unisys.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: xen does not see more than 173800500k of memory
Date: Thu, 23 Aug 2007 16:53:16 +0100	[thread overview]
Message-ID: <C2F36BFC.14834%keir@xensource.com> (raw)
In-Reply-To: <46CDBB18.76E4.0078.0@novell.com>

It's not a Xen security risk though. If you happen to use a compat guest
with page flipping then it just won't work. I think it's fair to say at this
point that that is just 'too bad'. If anyone really cares then they will
need to add a copy-to-low-memory path in Xen's page transfer code. The 166GB
restriction has to go.

 -- Keir

On 23/8/07 15:51, "Jan Beulich" <jbeulich@novell.com> wrote:

>>>> Keir Fraser <keir@xensource.com> 23.08.07 16:27 >>>
>> This should be easily fixed by properly applying
>> domain_clamp_alloc_bitsize() in __alloc_domheap_pages(). Why is it only
>> applied when the bitsize is explicitly specified by the caller?
>> 
>> I think that's the only thing to fix to allow the 166GB boot-time
>> restriction to be lifted, but am I missing something, Jan?
> 
> We had this discussion before - the problem is not restricting the allocations
> a domain does, but pages getting passed to it from other domains, which (if
> they happen to lie outside the 166Gb range) the domain then can't control.
> And yes, you said page flipping is basically dead, but this isn't being
> enforced (and probably can't as long as you want to support older guests
> potentially using it).
> 
> Jan
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

  reply	other threads:[~2007-08-23 15:53 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-22 22:33 xen does not see more than 173800500k of memory Krysan, Susan
2007-08-22 22:38 ` Keir Fraser
2007-08-23  7:34 ` Jan Beulich
2007-08-23 14:27   ` Keir Fraser
2007-08-23 14:51     ` Jan Beulich
2007-08-23 15:53       ` Keir Fraser [this message]
  -- strict thread matches above, loose matches on Subject: below --
2007-09-05 16:45 Subrahmanian, Raj

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