From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: Paravirtualizing bits of acpi access Date: Sun, 22 Mar 2009 14:17:44 +0100 Message-ID: <200903221417.45418.rjw@sisk.pl> References: <49C484B7.20100@goop.org> <200903221228.40181.rjw@sisk.pl> <20090322131436.GB22848@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from ogre.sisk.pl ([217.79.144.158]:53601 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752332AbZCVNRw (ORCPT ); Sun, 22 Mar 2009 09:17:52 -0400 In-Reply-To: <20090322131436.GB22848@elte.hu> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Ingo Molnar Cc: Jeremy Fitzhardinge , "Brown, Len" , linux-acpi@vger.kernel.org, Xen-devel , the arch/x86 maintainers On Sunday 22 March 2009, Ingo Molnar wrote: > > * Rafael J. Wysocki wrote: > > > On Sunday 22 March 2009, Jeremy Fitzhardinge wrote: > > > Rafael J. Wysocki wrote: > > > > Well, why don't you implement the platform suspend operations for Xen? > > > > I guess you don't want ACPI _PTS to be executed during suspend as well. > > > > > > > > > > I don't know. What's _PTS? > > > > It's an ACPI method called to prepare the platform to enter the sleep state > > (the name stands for "prepare to sleep"). Executing it may affect the > > hardware. > > > > > I think for the most part we want Linux to do most of the acpi > > > work of bringing the machine into an idle state. Its just that > > > Xen is responsible for the very low level cpu context > > > save/restore, because the Linux kernel is still running on vcpus > > > rather than the physical cpus. > > > > I think you really should not execute any global ACPI methods to > > suspend a guest, because that may affect the host. That's why I > > think it's better to regard Xen as a platform and implement a > > separate set of suspend operations for it. > > I'd agree with that. That also allows the reuse of existing > callbacks, right? Yes, it does. Rafael