From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261256AbUKSFa3 (ORCPT ); Fri, 19 Nov 2004 00:30:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261263AbUKSFa3 (ORCPT ); Fri, 19 Nov 2004 00:30:29 -0500 Received: from waste.org ([209.173.204.2]:20364 "EHLO waste.org") by vger.kernel.org with ESMTP id S261256AbUKSFaZ (ORCPT ); Fri, 19 Nov 2004 00:30:25 -0500 Date: Thu, 18 Nov 2004 21:29:36 -0800 From: Matt Mackall To: dhowells@redhat.com Cc: torvalds@osdl.org, akpm@osdl.org, davidm@snapgear.com, linux-kernel@vger.kernel.org, uclinux-dev@uclinux.org Subject: Re: [PATCH 17/20] FRV: Better mmap support in uClinux Message-ID: <20041119052936.GE8040@waste.org> References: <20040401020550.GG3150@beast> <200411081434.iA8EYKn7023613@warthog.cambridge.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200411081434.iA8EYKn7023613@warthog.cambridge.redhat.com> User-Agent: Mutt/1.3.28i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 08, 2004 at 02:34:20PM +0000, dhowells@redhat.com wrote: > (3) Files (and blockdevs) cannot be mapped shared since it is not > really possible to honour this by writing any changes back to the > backing device. [way behind on email] I think this could be done at msync, munmap and exit time? You end up flushing the entire mapping, but it's still correct (and POSIX compliant). And, if you wanted to be really clever, you could store a hash of each page to detect changes and avoid the extra I/O. -- Mathematics is the supreme nostalgia of our time.