From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joanna Rutkowska <joanna@invisiblethingslab.com>
Subject: scrubbing pages on vm pause
Date: Tue, 25 May 2010 16:12:53 +0200
Message-ID: <4BFBDAE5.4000805@invisiblethingslab.com>
References: <C8218854.151AD%keir.fraser@eu.citrix.com>
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To: Keir Fraser <keir.fraser@eu.citrix.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Rafal Wojtczuk <rafal@invisiblethingslab.com>
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On 05/25/2010 02:59 PM, Keir Fraser wrote:
> On 25/05/2010 13:50, "Rafal Wojtczuk" <rafal@invisiblethingslab.com> wr=
ote:
>=20
>>> There is no guarantee that the memory will be zeroed.
>> Interesting.
>> For my education, could you explain who is responsible for clearing me=
mory
>> of a newborn domain ? Xend ? Could you point me to the relevant code
>> fragments ?
>=20
> New domains are not guaranteed to receive zeroed memory. The only guara=
ntee
> Xen provides is that when it frees memory for a *dead* domain, it will =
scrub
> the contents before reallocation (it may not write zeroes however, in a=

> debug build of Xen for example!). Other memory pages the domain freeing=
 the
> pages must scrub them itself before freeing them back to Xen.
>=20

And what happens when we pause and save a domain? Are the pages zero-out
by xen in that case?

joanna.


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