From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754142Ab2BVRDJ (ORCPT ); Wed, 22 Feb 2012 12:03:09 -0500 Received: from mga03.intel.com ([143.182.124.21]:49921 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752608Ab2BVRDF convert rfc822-to-8bit (ORCPT ); Wed, 22 Feb 2012 12:03:05 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="69136193" From: "Liu, Jinsong" To: Konrad Rzeszutek Wilk , "lenb@kernel.org" , "Brown, Len" CC: "xen-devel@lists.xensource.com" , Kernel development list , "linux-acpi@vger.kernel.org" , "keir.xen@gmail.com" , Jan Beulich , "Li, Shaohua" , "lenb@kernel.org" Subject: RE: [Xen-devel] [PATCH 1/3] PAD helper for native and paravirt platform Thread-Topic: [Xen-devel] [PATCH 1/3] PAD helper for native and paravirt platform Thread-Index: AQHM8KTtqETlTTaR00eoPTQ1GukvM5ZJIhXg Date: Wed, 22 Feb 2012 17:02:59 +0000 Message-ID: References: <20120217142909.GA29110@phenom.dumpdata.com> <20120217144742.GA29454@phenom.dumpdata.com> <20120219182339.GA11882@phenom.dumpdata.com> <20120221142724.GB5652@phenom.dumpdata.com> In-Reply-To: <20120221142724.GB5652@phenom.dumpdata.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Konrad Rzeszutek Wilk wrote: > On Tue, Feb 21, 2012 at 05:49:58AM +0000, Liu, Jinsong wrote: >> Konrad Rzeszutek Wilk wrote: >>>>>>> +struct pv_pad_ops { >>>>>>> + int (*acpi_pad_init)(void); >>>>>>> + void (*acpi_pad_exit)(void); >>>>>>> +}; >>>>>>> + >>>>> >>>>> Looking at this a bit closer I am not sure why you choose the >>>>> paravirt interface for this? There is another one - the x86 that >>>>> could have been choosen. Or introduce a new one that is specific >>>>> to ACPI. >>>>> >>>>> I am curious - what was the reason for using the paravirt >>>>> interface? I understand it does get the job done, but it seems a >>>>> bit overkill when something simple could have been used? >>>>> >>>> >>>> It uses paravirt interface to avoid some code like 'xen_...' in >>>> native code path (acpi_pad.c). >>>> I'm not quite sure what does 'x86' here mean? Adding 2 fields >>>> (acpi_pad_init/exit) in arch/x86/xen/enlighten.c --> xen_cpu_ops? >>>> seems it's much simpler. >>> >>> arch/x86/include/asm/x86_init.h >>> >>> But before you go that way let me ask you another question - can >>> ACPI PAD be used on ARM or IA64? If so, wouldn't this fail >>> compilation as this pvops structure is not defined on IA64? >> >> Ideally ACPI PAD is not bound to some arch, so IMO it could be used >> at least on IA64 (through currently no real PAD on IA64 platform as >> far as I know). However, in native acpi_pad implementation, it >> indeed depends on X86 for reason like mwait. >> So for xen acpi_pad, I think it's OK to choose x86, defining an >> acpi_pad_ops at x86_init.c which would be overwritten when xen init. > > OK, or in osl.c. We need Len to chime in here as I can see this > expanding in the future. >> >> Another choice is to define config ACPI_PROCESSOR_AGGREGATOR as >> 'bool', which would disable native acpi_pad module. > > Ewww. No. I'm OK with x86_init approach, but advantage of 'config ACPI_PROCESSOR_AGGREGATOR as bool' would get rid of X86/IA64/... arch issue for xen (at least from coding view), through it need disable native acpi_pad module (IMO acpi_pad module has not strong reason to must be so). Have a re-consider of this approach? :-) Thanks, Jinsong >> >> Your opinion? >> >> Thanks, >> Jinsong >> >>> >>> The other thing I am not comfortable about is that the pvops >>> structure are used for low-level code. Not for higher up, like >>> ACPI. For that another structure seems more prudent. Perhaps >>> something like the x86 one, but specific to ACPI?