Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030282AbXFHIB3 (ORCPT ); Fri, 8 Jun 2007 04:01:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S938485AbXFHH0W (ORCPT ); Fri, 8 Jun 2007 03:26:22 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:35624 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S938402AbXFHH0U (ORCPT ); Fri, 8 Jun 2007 03:26:20 -0400 Date: Fri, 8 Jun 2007 08:26:09 +0100 From: Christoph Hellwig To: carsteno@de.ibm.com Cc: Christoph Hellwig , Jared Hulbert , Nick Piggin , Andrew Morton , richard.griffiths@windriver.com, Richard Griffiths , Linux-kernel@vger.kernel.org Subject: Re: [PATCH 2.6.21] cramfs: add cramfs Linear XIP Message-ID: <20070608072609.GA13115@infradead.org> Mail-Followup-To: Christoph Hellwig , carsteno@de.ibm.com, Jared Hulbert , Nick Piggin , Andrew Morton , richard.griffiths@windriver.com, Richard Griffiths , Linux-kernel@vger.kernel.org References: <6934efce0706011748p46cf7995vdca0b9cc3f0b06a3@mail.gmail.com> <46612D6F.6000002@yahoo.com.au> <46641472.3080802@de.ibm.com> <6934efce0706060413y6e74512s19d5f468106d4b85@mail.gmail.com> <20070606113351.GA11701@infradead.org> <4666DD88.5030708@de.ibm.com> <20070606162305.GA20600@infradead.org> <46683B6A.6030306@de.ibm.com> <20070607193844.GB17144@infradead.org> <4669027E.3070406@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4669027E.3070406@de.ibm.com> User-Agent: Mutt/1.4.2.2i X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1731 Lines: 32 On Fri, Jun 08, 2007 at 09:17:18AM +0200, Carsten Otte wrote: > Christoph Hellwig wrote: > >On Thu, Jun 07, 2007 at 07:07:54PM +0200, Carsten Otte wrote: > >>I've had a few beer long discussion with Joern Engel and David > >>Woodhouse on this one. To cut a long discussion short: the current XIP > >>infrastructure is not sufficient to be used on top of mtd. We'd need > >>some extenstions: > >>- on get_xip_page() we'd need to state if we want the reference > >>read-only or read+write > >>- we need a put_xip_page() to return references > >>- and finally we need a callback for the referece, so that the mtd > >>driver can ask to get its reference back (in order to unmap from > >>userland when erasing a block) > > > >And we'll need that even when using cramfs. There's not way we'd > >merge a hack where the user has to specify a physical address on > >the mount command line. > Nay, the proposed solution is read only. From what I understood of the > discussion, it does'nt need that. The entire flash memory can be read > at the same time. Things start to get interresting when you want to > write, then you need to care about erase blocks and such. We can have a simpler variant as a start if we really want. But we need to pass it through the mtd layer. There is a reason we have this thing called devices drivers, and we don't want to add knowledge of ioremap to the filesystems and have users find out physical addresses of their flash to pass it as mount option. - 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/