Re: [Xen-devel] [PATCH 1/3] PAD helper for native and paravirt platform

[Konrad Rzeszutek Wilk <konrad@darnok.org>]

On Fri, Feb 17, 2012 at 08:56:43AM +0000, Liu, Jinsong wrote:
> >From f66a2df1392bbe69426387657a220177be50d58a Mon Sep 17 00:00:00 2001
> From: Liu, Jinsong <jinsong.liu@intel.com>
> Date: Fri, 10 Feb 2012 20:32:50 +0800
> Subject: [PATCH 1/3] PAD helper for native and paravirt platform
> 
> This patch is PAD (Processor Aggregator Device) helper.
> It provides a native interface for natvie platform, and a template
> for paravirt platform, so that os can implicitly hook to proper ops accordingly.
> The paravirt template will further redirect to Xen pv ops in later patch for Xen
>  core parking.

Liu,

With this patch: "  xen/enlighten: Expose MWAIT and MWAIT_LEAF if
hypervisor OKs it." which is now in 3.4-rc0:
(http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blobdiff;f=arch/x86/xen/enlighten.c;h=b132ade26f778f2cfec7c2d5c7b6db48afe424d5;hp=4172af8ceeb363d06912af15bf89e8508752b794;hb=d4c6fa73fe984e504d52f3d6bba291fd76fe49f7;hpb=aab008db8063364dc3c8ccf4981c21124866b395)
it means that now that the drivers/acpi/acpi_pad.c can run
as is under Xen (as the MWAIT_LEAF is exposed) What is the impact
of that? Is the monitor call causing a trap to the hypervisor which will
ignore the call? Or will it have some more worrysome consequences?

Thanks!