From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753549Ab1AFPpw (ORCPT ); Thu, 6 Jan 2011 10:45:52 -0500 Received: from canuck.infradead.org ([134.117.69.58]:49382 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753523Ab1AFPpu (ORCPT ); Thu, 6 Jan 2011 10:45:50 -0500 Subject: Re: [PATCH] mtd: allow mtd and jffs2 when ARCH=um From: David Woodhouse To: Jason Lunz Cc: Artem Bityutskiy , richard -rw- weinberger , Sam Ravnborg , atom ota , user-mode-linux-devel@lists.sourceforge.net, Jeff Dike , lkml , linux-mtd@lists.infradead.org, Rob Landley Date: Thu, 06 Jan 2011 15:45:34 +0000 In-Reply-To: <20101214195124.GA6010@falooley.org> References: <22c797d00709272118i33d32b9dy93d5f5ec8f8edd30@mail.gmail.com> <20071024011712.GA3762@falooley.org> <1193208689.26096.48.camel@pmac.infradead.org> <20071227181524.GA19051@falooley.org> <20071228174853.GA4252@uranus.ravnborg.org> <20101207072919.GA8511@falooley.org> <20101207182012.GA10546@falooley.org> <1292343878.2538.80.camel@localhost> <20101214195124.GA6010@falooley.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 2.91.5 Content-Transfer-Encoding: 7bit Message-ID: <1294328738.20779.10.camel@i7.infradead.org> Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by canuck.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-12-14 at 11:51 -0800, Jason Lunz wrote: > > > Instead, you should solve this problem in UML code. I do not know how, > > but may be you can add readb/writeb there which actually do nothing or > > print a scary warning, or do BUG(), and let things which use them just > > fail run-time. > > Something like this could work, but it would be error-prone for anyone > else who attempts using iomem-requiring drivers on uml. Instead of > getting obvious compile failures we'd have broken drivers that BUG() or > emit scary warnings. That doesn't seem to me like an improvement. Drivers should *never* BUG() or crash, or busy-loop, on getting 0xFF when they read from hardware. That can happen anyway in some circumstances. Doesn't iSeries take this approach? I don't much like the patch that Artem took into his l2-mtd tree; it doesn't even let you build mtdchar, which really *ought* to be permitted. It also didn't allow the nandsim or mtdram devices, which are purely virtual. I think I'd prefer something similar to your original, Jason. I don't think the HAS_IOMEM dependencies have to be *so* complex to maintain. If anything we're just going to err on the side of inclusion and you'll occasionally have to send us patches to "hide" things from you again. -- David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation