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Date: Mon, 28 Apr 2008 10:06:02 +0300
From: Avi Kivity <avi@qumranet.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [4270] bios: disable processor SSDT generation.
References: <E1JqGZE-0007Es-Le@cvs.savannah.gnu.org>	<5b31733c0804272033q1b13c435l56c1d1bb9340037b@mail.gmail.com>
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To: Aurelien Jarno <aurelien@aurel32.net>
Cc: qemu-devel@nongnu.org

Aurelien Jarno wrote:
> Filip Navara a =E9crit :
>  =20
>> Under which operating system and in which conditions? Some operating
>>    =20
>
> Basically on all systems I tried, that is Linux, Windows 2k and Windows
> XP. This happens for both 32- and 64-bits hosts.
>
>  =20
>> systems I use under QEMU require the processor descriptors and I've
>> been told that certain version of Windows Vista doesn't idle if the
>> processsor descriptors aren't present.
>>    =20
>
> I am open to a proper fix, but I think that breaking support for most
> guests to support Windows Vista is a serious regression.

kvm has processor descriptor and proper idle for all guests including=20
Vista.=20

The following commit is probaby needed:

> commit cb98751267c2d79f5674301ccac6c6b5c2e0c6b5
> Author: Igor Lvovsky <igorl@qumranet.com>
> Date:   Sun Aug 19 14:54:08 2007 +0300
>
>     kvm: bios: don't advertise ACPI C2 or C3 support
>
>     The previous patch fix the SMP guest problem, but
>     now UP guest with SMP HAL consume ~50% CPU (it was 2-3% before that
>     with UP HAL).  To fix it we need disable support of C2 and C3 state=
s
>     via FADT.
>
>     Signed-off-by: Igor Lvovsky <igorl@qumranet.com>
>     Signed-off-by: Avi Kivity <avi@qumranet.com>
>

I'd like to properly support C3 and revert that patch, but that can come=20
later.

--=20
Any sufficiently difficult bug is indistinguishable from a feature.