Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759556AbYBNReA (ORCPT ); Thu, 14 Feb 2008 12:34:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753608AbYBNRdt (ORCPT ); Thu, 14 Feb 2008 12:33:49 -0500 Received: from e3.ny.us.ibm.com ([32.97.182.143]:57108 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751850AbYBNRds (ORCPT ); Thu, 14 Feb 2008 12:33:48 -0500 Subject: Re: [PATCH] drivers/base: export gpl (un)register_memory_notifier From: Badari Pulavarty To: Dave Hansen Cc: Christoph Raisch , ossthema@linux.vnet.ibm.com, apw , Greg KH , Jan-Bernd Themann , linux-kernel , linuxppc-dev@ozlabs.org, netdev , Thomas Q Klein , tklein@linux.ibm.com In-Reply-To: <1203009163.19205.42.camel@nimitz.home.sr71.net> References: <200802111724.12416.ossthema@de.ibm.com> <1202748429.8276.21.camel@nimitz.home.sr71.net> <200802131617.58646.ossthema@de.ibm.com> <1203009163.19205.42.camel@nimitz.home.sr71.net> Content-Type: text/plain Date: Thu, 14 Feb 2008 09:36:15 -0800 Message-Id: <1203010575.12312.6.camel@dyn9047017100.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.0.4 (2.0.4-4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1779 Lines: 40 On Thu, 2008-02-14 at 09:12 -0800, Dave Hansen wrote: .. > > > > - Use currently other not exported functions in kernel/resource.c, like > > > > walk_memory_resource (where we would still need the maximum > > > possible number > > > > of pages NR_MEM_SECTIONS) > > > > > > It isn't the act of exporting that's the problem. It's making sure that > > > the exports won't be prone to abuse and that people are using them > > > properly. You should assume that you can export and use > > > walk_memory_resource(). > > > > So this seems to come down to a basic question: > > New hardware seems to have a tendency to get "private MMUs", > > which need private mappings from the kernel address space into a > > "HW defined address space with potentially unique characteristics" > > RDMA in Openfabrics with global MR is the most prominent example heading > > there > > That's not a question. ;) > > Please explain to me why walk_memory_resource() is insufficient for your > needs. I've now pointed it out to you at least 3 times. I am not sure what you are trying to do with walk_memory_resource(). The behavior is different on ppc64. Hotplug memory usage assumes that all the memory resources (all system memory, not just IOMEM) are represented in /proc/iomem. Its the case with i386 and ia64. But on ppc64 is contains ONLY iomem related. Paulus didn't want to export all the system memory into /proc/iomem on ppc64. So I had to workaround by providing arch-specific walk_memory_resource() function for ppc64. Thanks, Badari -- 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/