From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Anthony Wright <anthony@overnetdata.com>, xen-devel@lists.xen.org
Subject: Re: xen/xen vs xen/kvm nesting with pv drivers
Date: Tue, 6 Sep 2016 14:05:28 +0100 [thread overview]
Message-ID: <8beb1018-5b07-7e06-3d13-c27d5ce2a7fe@citrix.com> (raw)
In-Reply-To: <21926294.38.1473166034486.JavaMail.root@zimbra.overnetdata.com>
On 06/09/16 13:47, Anthony Wright wrote:
> I tried to install Xen (4.7.0 with linux 4.7.2 Dom0) on an AWS virtual machine and it failed because while AWS uses Xen it requires that you use the PVHVM network driver. I then tried to install Xen on a Google Cloud virtual machine and despite also requiring you to use PV drivers, that succeeded because Google Cloud uses KVM.
>
> I think this means that if you nest Xen in KVM you can use high performance drivers, but if you nest Xen in Xen you have to use slower drivers, which seems to be the wrong way around!
>
> I'd like to be able to install Xen on an AWS virtual machine, and wondered what are the challenges to getting the pv drivers working in a nested environment. Is this a problem with the Dom0 kernel only expecting there to be a single XenStore, or is there also a problem in Xen?
Nesting Xen inside Xen and getting high-speed drivers at L1 is a hard
problem, which is why noone has tackled it yet.
The problems all revolve around L1's dom0. It can't issue hypercalls to
L0, meaning that it cant find or connect the xenstore ring. Even if it
could, there is the problem of multiple xenstores, which doesn't fit in
the current architecture.
It would be lovely if someone would work on this, but it is a very large
swamp.
~Andrew
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next prev parent reply other threads:[~2016-09-06 13:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <27810356.26.1473165229135.JavaMail.root@zimbra.overnetdata.com>
2016-09-06 12:47 ` xen/xen vs xen/kvm nesting with pv drivers Anthony Wright
2016-09-06 13:05 ` Andrew Cooper [this message]
2016-09-06 13:32 ` Anthony Wright
2016-09-06 14:36 ` Andrew Cooper
2016-09-06 15:40 ` Konrad Rzeszutek Wilk
2016-09-06 17:31 ` Konrad Rzeszutek Wilk
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