[Xen-devel] Send data from hypervisor to Dom0?

To:	"Xen Developers" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject:	[Xen-devel] Send data from hypervisor to Dom0?
From:	"Jun Koi" <junkoi2004@xxxxxxxxx>
Date:	Tue, 29 Aug 2006 23:16:50 +0900
Delivery-date:	Tue, 29 Aug 2006 07:17:18 -0700
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Good morning,

I am working on a project that does some system profiling at
hypervisor level. I want to send some data from hypervisor to Dom0,
and each time the data to be sent are quite small: only 8 bytes.

I imagine that each time after sending data to Dom0, hypervisor needs
to somehow notify Dom0 about the data it has just sent.

I am studying Xen and it looks like I can do it in 2 ways:

1) Shared memory: hypervisor can share memory with Dom0 to send data,
like what the console code is doing. But this approach may waste too
much money, like 1 memory page for only 8 bytes data! That does not
look good to me.

2) Hypervisor writes data to XenStore, but I am not sure if it is
possible to do that from hypervisory layer? (Any hints for me on how
to do that, if it is possible?).

Either of the above 2 ways, hypervisor can notify Dom0 via
event-channel (This event-channel needs to be initialized when Dom0
boots up)

Anybody could give me some suggestions on this problem? All the help
are greatly appreciated :-)

Thanks.
Jun

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