From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964784AbXCUU0y (ORCPT ); Wed, 21 Mar 2007 16:26:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964871AbXCUU0y (ORCPT ); Wed, 21 Mar 2007 16:26:54 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:39406 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964784AbXCUU0x (ORCPT ); Wed, 21 Mar 2007 16:26:53 -0400 Subject: Re: pagetable_ops: Hugetlb character device example From: Adam Litke To: Valdis.Kletnieks@vt.edu Cc: Andrew Morton , Arjan van de Ven , William Lee Irwin III , Christoph Hellwig , Ken Chen , linux-mm@kvack.org, linux-kernel@vger.kernel.org In-Reply-To: <200703211951.l2LJpVPS020364@turing-police.cc.vt.edu> References: <20070319200502.17168.17175.stgit@localhost.localdomain> <1174506228.21684.41.camel@localhost.localdomain> <200703211951.l2LJpVPS020364@turing-police.cc.vt.edu> Content-Type: text/plain Date: Wed, 21 Mar 2007 15:26:44 -0500 Message-Id: <1174508804.21684.48.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2007-03-21 at 15:51 -0400, Valdis.Kletnieks@vt.edu wrote: > On Wed, 21 Mar 2007 14:43:48 CDT, Adam Litke said: > > The main reason I am advocating a set of pagetable_operations is to > > enable the development of a new hugetlb interface. > > Do you have an exit strategy for the *old* interface? Not really. Hugetlbfs needs to be kept around for a number of reasons. It was designed to support MAP_SHARED mappings and IPC shm segments. It is probably still the best interface for those jobs. Of course hugetlbfs has lots of users so we must preserve the interface for them. But... once hugetlbfs is abstracted behind pagetable_operations, you would have the option of configuring it out of the kernel without losing access to huge pages by other means (such as the character device). -- Adam Litke - (agl at us.ibm.com) IBM Linux Technology Center