[Xen-devel] How to detect HAP from DomU?

To:	"xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject:	[Xen-devel] How to detect HAP from DomU?
From:	Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
Date:	Wed, 10 Nov 2010 09:22:50 +0100
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Hi,

is there any way for a HVM-domain to detect whether it is running with HAP
enabled? I couldn't find any interface for this information.

Background: in our BS2000 domain (HVM with PV-drivers) we sometimes have to
copy complete pages between kernel and user. An alternative to the copy
would be a remapping of the page. The remap is faster than the copy with HAP
enabled, but much slower without HAP. So it would be best to copy without HAP
and remap with HAP.

I think this would be a candidate for XEN features (another bit in
xen/include/public/features.h). If there are no objections to this idea, I'll
make a patch.


Juergen

--
Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 3222 2967
Fujitsu Technology Solutions              e-mail: juergen.gross@xxxxxxxxxxxxxx
Domagkstr. 28                           Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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[Xen-devel] How to detect HAP from DomU?