From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756137AbXIKQ5y (ORCPT ); Tue, 11 Sep 2007 12:57:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762345AbXIKQ5m (ORCPT ); Tue, 11 Sep 2007 12:57:42 -0400 Received: from mx1.redhat.com ([66.187.233.31]:34061 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762019AbXIKQ5l (ORCPT ); Tue, 11 Sep 2007 12:57:41 -0400 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20070911112526.GK15405@kernel.dk> References: <20070911112526.GK15405@kernel.dk> <20070911093510.GA15405@kernel.dk> <20070911082307.GB19495@linux-sh.org> <9949.1189505419@redhat.com> To: Jens Axboe Cc: dhowells@redhat.com, Paul Mundt , Andrew Morton , Greg Ungerer , linux-kernel@vger.kernel.org Subject: Re: [PATCH -mm] splice: Disable vmsplice on nommu. X-Mailer: MH-E 8.0.3; nmh 1.2-20070115cvs; GNU Emacs 22.1.50 Date: Tue, 11 Sep 2007 17:57:17 +0100 Message-ID: <13455.1189529837@redhat.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jens Axboe wrote: > > > It's a bit of a sledge hammer... Since get_user_pages() appears to work > > > on nummu, we can just disable the vmsplice-to-userspace bits and leave > > > the (working) vmsplice-from-userspace in place. > > > > That sounds about right. I don't think you can do the latter without > > an MMU, but I may be wrong about what it does. > > You mean the former? The latter is vmsplice() filling a pipe with user > pages, using get_user_pages() to set them up. And that looks like it > should work on nommu. > > The former is vmsplice() using mmap like functionality to map pages into > a user vma. Sorry, yes. The former. David