From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from an-out-0708.google.com (an-out-0708.google.com [209.85.132.244]) by ozlabs.org (Postfix) with ESMTP id 81A9BDE02E for ; Tue, 1 Apr 2008 23:03:37 +1100 (EST) Received: by an-out-0708.google.com with SMTP id c37so516960anc.78 for ; Tue, 01 Apr 2008 05:03:36 -0700 (PDT) Subject: Re: [kvm-ppc-devel] [PATCH] Add idle power save for ppc 4xx From: Josh Boyer To: Jimi Xenidis In-Reply-To: <11F8A893-409D-4449-9DAB-BF248045E6D9@pobox.com> References: <10aea37177130bbe5de7.1206969157@thinkpadL> <1206983237.12155.60.camel@vader.jdub.homelinux.org> <20080331130518.2a6b0264@zod.rchland.ibm.com> <1206987598.9165.10.camel@thinkpadL> <1207011862.7490.5.camel@concordia.ozlabs.ibm.com> <1207019732.12155.81.camel@vader.jdub.homelinux.org> <11F8A893-409D-4449-9DAB-BF248045E6D9@pobox.com> Content-Type: text/plain Date: Tue, 01 Apr 2008 07:03:26 -0500 Message-Id: <1207051406.12155.88.camel@vader.jdub.homelinux.org> Mime-Version: 1.0 Cc: kvm-ppc-devel@lists.sourceforge.net, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 2008-04-01 at 08:01 -0400, Jimi Xenidis wrote: > On Mar 31, 2008, at 11:15 PM, Josh Boyer wrote: > > > On Tue, 2008-04-01 at 12:04 +1100, Michael Ellerman wrote: > >>>>> I'm assuming you pass a dtb to the virtual guest when you start > >>>>> it up. > >>>>> Could you define a property in the CPU node there that can be > >>>>> parsed to > >>>>> use the power_save function instead of always making it the > >>>>> default? > >>>> > >>>> Actually, you probably don't want this as a property in the device > >>>> tree. It doesn't describe hardware. A Kconfig option might be > >>>> warranted though. > >>> > >>> I'll go with the Kconfig option. > >> > >> Go with a device-tree check. The pseries kernel supports both bare- > >> metal > >> and hypervisor in the same kernel image, and it works out which it's > >> running on by looking at the device-tree. This seems equivalent to > >> me? > > > > After some back and forth on IRC, we decided on that as well. I love > > being right, then wrong, then right again. > > Awesome, can you summarize for the rest of us? A node or property will be in the device tree that the guests can use to determine if it's running under a hypervisor or not. The details are yet to be worked out, so there isn't much more of a summary yet. There was also some conversation about having an "idle=" kernel parameter similar to the PA-Semi port that would allow toggling of it as well. josh