Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755318Ab3DZQKi (ORCPT ); Fri, 26 Apr 2013 12:10:38 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:64174 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751276Ab3DZQKh (ORCPT ); Fri, 26 Apr 2013 12:10:37 -0400 Date: Fri, 26 Apr 2013 17:10:12 +0100 From: Will Deacon To: Stefano Stabellini Cc: Nicolas Pitre , "xen-devel@lists.xensource.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "arnd@arndb.de" , "rob.herring@calxeda.com" , "linux@arm.linux.org.uk" , "olof@lixom.net" Subject: Re: [PATCH v8 1/2] arm: introduce psci_smp_ops Message-ID: <20130426161012.GH30858@mudshark.cambridge.arm.com> References: <1366828819-10745-1-git-send-email-stefano.stabellini@eu.citrix.com> <20130425084711.GA12848@mudshark.cambridge.arm.com> <20130425104508.GG12848@mudshark.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1711 Lines: 36 On Fri, Apr 26, 2013 at 04:36:26PM +0100, Stefano Stabellini wrote: > On Thu, 25 Apr 2013, Nicolas Pitre wrote: > > On Thu, 25 Apr 2013, Will Deacon wrote: > > > I disagree. You're explicitly stating that we pass the `cpuid of target CPU, > > > as from MPIDR'. That's simply not true -- the firmware could choose any > > > numbering scheme to identify the CPUs. For KVM and Xen, it *is* the mpidr, > > > which is why psci-smp.c works at all, but that's where the comment belongs, > > > not in this header file. > > > > At some point, the _kernel_ API for interfacing with the firmware's PSCI > > will have to ensure uniformity somehow. The PSCI interface code could > > translate the passed MPIDR into whatever the firmware decided to use for > > identifying CPUs if needed, keeping this issue localized. > > That is what I had in mind when I said to keep the comment in psci.h > before. > We have to draw the line somewhere to expose a uniform internal kernel > API. However it is a bit difficult to do now given that we have only one > user of the API. I see psci.h as representing the firmware interface, and psci-smp.c or whatever sits on top as exposing the kernel `API'. > I don't feel to strongly about this, please let me know what is the > final decision and I'll update the code accordingly. I remind you that > the merge window is approaching :-) I'd still like the comment to be in psci-smp.c, or a header separate from the firmware bits. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/