This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] [PATCH] Paging and memory sharing for HVM guests

To: "Grzegorz Milos" <gm281@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Paging and memory sharing for HVM guests
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Thu, 17 Dec 2009 08:47:13 +0000
Cc: Patrick Colp <pjcolp@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Andrew Peace <Andrew.Peace@xxxxxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Delivery-date: Thu, 17 Dec 2009 00:47:37 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <db8ce2bd0912161514s7a162546gf7f5909db22e274c@xxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <db8ce2bd0912161514s7a162546gf7f5909db22e274c@xxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>>> Grzegorz Milos <gm281@xxxxxxxxx> 17.12.09 00:14 >>>
>The series of 46 patches attached to this email contain the initial
>implementation of memory paging and sharing for Xen. Patrick Colp
>leads the work on the pager, and I am mostly responsible for memory
>sharing. We would be grateful for any comments/suggestions you might
>have. Individual patches are labeled with comments describing their
>purpose and a sign-off footnote. Of course we are happy to discuss
>them in more detail, as required. Assuming that there are no major
>objections against including them in the mainstream xen-unstable tree,
>we would like to move future development to that tree.

An overview description of the design would be nice, to have a basic
understanding before looking at the individual patches. In particular,
from a first brief look, I'm having the impression that only HVM guests'
pages can be subject to paging.

On the Linux patches:

Introducing another bogus failure indicator for the mmap_batch
privcmd operations seems rather undesirable - we'll already need to
find a backwards-compatible solution to the current (broken) or-ing
in of 0xf0000000 (broken because MFNs can now be more than
28 bits wide).

Using msleep() with hard-coded values (in at least one case even
contradicting the accompanying comment) seems more like a hack
than a permanent solution. Can't there be some signaling done, or
can't there alternatively be a polling hypercall?

Removing support for IOCTL_PRIVCMD_MMAP from the pv-ops
implementation seems pretty unrelated, so should probably be a
separate patch.

Also, most of the patches seem to use blanks instead of tabs for
indentation, and occasionally other non-standard formatting.


Xen-devel mailing list