From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030462AbWGIMPv (ORCPT ); Sun, 9 Jul 2006 08:15:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030469AbWGIMPv (ORCPT ); Sun, 9 Jul 2006 08:15:51 -0400 Received: from mail.gmx.de ([213.165.64.21]:29128 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1030462AbWGIMPu (ORCPT ); Sun, 9 Jul 2006 08:15:50 -0400 X-Authenticated: #2769515 Date: Sun, 9 Jul 2006 14:21:18 +0200 From: Martin Langer To: Marcel Holtmann Cc: Arjan van de Ven , linux-kernel@vger.kernel.org, bcm43xx-dev@lists.berlios.de Subject: Re: [RFC][PATCH 1/2] firmware version management: add firmware_version() Message-ID: <20060709122118.GA3678@tuba> References: <20060708130904.GA3819@tuba> <1152365514.3120.46.camel@laptopd505.fenrus.org> <1152366597.29506.13.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1152366597.29506.13.camel@localhost> X-Public-Key-URL: http://www.langerland.de/martin/martinlanger.asc User-Agent: Mutt/1.5.9i X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 08, 2006 at 03:49:57PM +0200, Marcel Holtmann wrote: > Hi Arjan, > > > > It would be good if a driver knows which firmware version will be > > > written to the hardware. I'm talking about external firmware files > > > claimed by request_firmware(). > > > > > > We know so many different firmware files for bcm43xx and it becomes > > > more and more complicated without some firmware version management. > > > > > > This patch can create the md5sum of a firmware file. Then it looks into > > > a table to figure out which version number is assigned to the hashcode. > > > That table is placed in the driver code and an example for bcm43xx comes > > > in my next mail. Any comments? > > > > why does this have to happen on the kernel side? Isn't it a lot easier > > and better to let the userspace side of things do this work, and even > > have a userspace file with the md5->version mapping? Or are there some > > practical considerations that make that hard to impossible? > > I fully agree that we shouldn't put firmware versioning into the kernel > drivers. The pattern you give to request_firmware() can be mapped to any > file on the file system. And you also have the link to the device object > and I prefer you export a sysfs file for the version so that the helper > application loading the firmware can pick the right file. Bcm43xx has no helper application to upload the firmware. This is done in the driver. It's RAM based hardware without a Flash-ROM. The driver has to upload the firmware in the init phase after each reset. The driver gets a firmware file from /lib/firmware/ without knowing which version this is. It's not possible to say enable this in the driver if you find a firmware x and disable that if it's only version y. That was my motivation to start thinking about firmware versioning. But in the meantime I think it's a security issue, too. A driver should only accept firmware files with certified checksums. I guess it would be really difficult to enter a machine by firmware hijacking. So, I'm still in hope that this is only a paranoia on my side. But it's worth to think about it. Martin