Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262902AbUAMBcK (ORCPT ); Mon, 12 Jan 2004 20:32:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263015AbUAMBcJ (ORCPT ); Mon, 12 Jan 2004 20:32:09 -0500 Received: from mta4-svc.business.ntl.com ([62.253.164.44]:56299 "EHLO mta4-svc.business.ntl.com") by vger.kernel.org with ESMTP id S262902AbUAMBcC (ORCPT ); Mon, 12 Jan 2004 20:32:02 -0500 Date: Tue, 13 Jan 2004 01:31:03 +0000 (GMT) From: Bart Oldeman X-X-Sender: enbeo@enm-bo-lt.enm.bris.ac.uk To: Linus Torvalds cc: linux-kernel@vger.kernel.org, Subject: Re: [PATCH] 2.6.1 (not 2.4.24!) mremap fixes broke shm alias mappings In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1606 Lines: 39 On Mon, 12 Jan 2004, Linus Torvalds wrote: > On Sun, 11 Jan 2004, Bart Oldeman wrote: > > > > DOSEMU needs to alias memory, for instance to emulate the HMA. A long time > > ago this was done using mmaps of /proc/self/mem. This was replaced by > > mremap combined with IPC SHM during 2.1 development. > > > > According to DOSEMUs changelog you agreed to allow old_len==0: > > - using _one_ big IPC shm segment and mremap(addr, 0 ...) > > (Linus agreed on keeping shmat()+mremap(,0,..) functionality) > > so you agreed on something you have removed after all now! > > Hey, I wouldn't remember all the special cases that aren't commented. But > I agree that a zero "old_len" is not bad in itself, and if DOSEMU uses it, > let's just continue to support it, and document it while we're at it. > > So if this makes DOSEMU happy again, let's do it.. > > Pls confirm. sure, it's fine this way. Thanks! We've already been discussing and playing with a cleaner alternative to mremap that works too (mmap'ing a file on tmpfs, perhaps via shm_open()). It's just that it's difficult to explain to users why DOSEMU worked on 2.6.0 and suddenly stopped working with the same configuration on 2.6.1. -- the consensus amongst DOSEMU developers seems to be that you should feel free to disallow this funny old_len==0 case in 2.7 if you like. Bart - 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/