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] Xen and Linux

To: Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Xen and Linux
From: "Dimitrie O. Paun" <dpaun@xxxxxxxxxx>
Date: Sat, 6 Nov 2004 00:15:36 -0500
Cc: "Dimitrie O. Paun" <dpaun@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxxx
Delivery-date: Sun, 07 Nov 2004 09:06:13 +0000
Envelope-to: steven.hand@xxxxxxxxxxxx
In-reply-to: <E1CQDVL-0003zp-00@xxxxxxxxxxxxxxxxx>
List-archive: <http://sourceforge.net/mailarchive/forum.php?forum=xen-devel>
List-help: <mailto:xen-devel-request@lists.sourceforge.net?subject=help>
List-id: List for Xen developers <xen-devel.lists.sourceforge.net>
List-post: <mailto:xen-devel@lists.sourceforge.net>
List-subscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=subscribe>
List-unsubscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=unsubscribe>
References: <20041105205453.GA21383@xxxxxxxxxx> <E1CQDVL-0003zp-00@xxxxxxxxxxxxxxxxx>
Sender: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.4.1i
On Fri, Nov 05, 2004 at 11:28:25PM +0000, Ian Pratt wrote:
> It would be very cool ;-) We might even get distros to ship it on
> their install CD...

Exactly where I was going ... :)

> There's one simple src change in arch Xen that has some quite far
> reaching consequences: we change FIXADDR_TOP which effectively
> gives us a 64MB whole at the top of the guest's VM space where
> Xen lives. This constant gets compiled into a bunch of different
> functions (though I believe it doesn't make it into modules
> --phew!).

Oh. Is there any way that the kernel can reuse that space
if it figures that it's not running under Xen. I haven't
looked too closely at the kernel's memory management, but
I seem to remember the zone allocators...

> I suspect it would be unpopular to make FIXADDR_TOP a variable,
> and it turns out to be a tricky thing to runtime patch. I think
> we just have to have arch-xen specific versions of all of the
> functions that use it.

Yes, in which case we could maybe turn it *there* into a variable.

> The simplest way to do this would be to have a tool that builds
> an x86 and xen kernel then merges the two together. Sounds a bit
> gross, but I think it would work quite well.

Maybe, but it would be bigger, and this maybe a problem for small
devices. Anyhow, not very satisfying :)

> Probably the cleanest solution of all would be to make all the
> other architectures adopt Xen's nice clean interfaces and then
> have stub routines for talking to the grotty realty of real
> hardware. Might be a hard one to sell to Linus et al though ;-)

Yeah, I'd think this would be the preferable route. How large
would such a patch be?. It may be worth it to float it on LKML 
to see the reaction :)


This SF.Net email is sponsored by:
Sybase ASE Linux Express Edition - download now for FREE
LinuxWorld Reader's Choice Award Winner for best database on Linux.
Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>